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WO2025231379A1 - Adhésifs de coacervat à l'état solide et leurs procédés de fabrication et d'utilisation - Google Patents

Adhésifs de coacervat à l'état solide et leurs procédés de fabrication et d'utilisation

Info

Publication number
WO2025231379A1
WO2025231379A1 PCT/US2025/027523 US2025027523W WO2025231379A1 WO 2025231379 A1 WO2025231379 A1 WO 2025231379A1 US 2025027523 W US2025027523 W US 2025027523W WO 2025231379 A1 WO2025231379 A1 WO 2025231379A1
Authority
WO
WIPO (PCT)
Prior art keywords
solid state
state composition
silk fibroin
coacervate
composition
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Pending
Application number
PCT/US2025/027523
Other languages
English (en)
Inventor
Fiorenzo G. Omenetto
Marco LO PRESTI
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
Tufts University
Original Assignee
Tufts University
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Tufts University filed Critical Tufts University
Publication of WO2025231379A1 publication Critical patent/WO2025231379A1/fr
Pending legal-status Critical Current
Anticipated expiration legal-status Critical

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09J—ADHESIVES; NON-MECHANICAL ASPECTS OF ADHESIVE PROCESSES IN GENERAL; ADHESIVE PROCESSES NOT PROVIDED FOR ELSEWHERE; USE OF MATERIALS AS ADHESIVES
    • C09J189/00—Adhesives based on proteins; Adhesives based on derivatives thereof
    • C—CHEMISTRY; METALLURGY
    • C07—ORGANIC CHEMISTRY
    • C07K—PEPTIDES
    • C07K14/00—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof
    • C07K14/435—Peptides having more than 20 amino acids; Gastrins; Somatostatins; Melanotropins; Derivatives thereof from animals; from humans

Definitions

  • One particularly challenging adhesive task is the fast labeling of marine animals.
  • shark skin is a very challenging surface for adhesion and current adhesives do not provide adequate adhesive performance for tagging purposes.
  • the techniques described herein relate to a solid state composition including a coacervate-forming pair of materials.
  • the coacervate-forming pair of materials include silk fibroin and a silk-complementary material that is capable of forming a coacervate with the silk fibroin.
  • the solid state composition includes a mixture of silk fibroin powder, which includes the silk fibroin, and complementary powder, which includes the silk-complementary material.
  • the silk fibroin and the silk-complementary material are present in the solid state composition in a weight ratio of between 1:10 and 100:1.
  • the techniques described herein relate to a solid state composition including a coacervate-forming pair of materials.
  • the coacervate-forming pair of materials consist of a first material and a complementary material that is capable of forming a coacervate with the first material.
  • the solid state composition includes or consists essentially of a mixture of a first powder, which includes the first material, and a second powder, which includes the complementary material. Hydrating and agitating the solid state composition forms the coacervate.
  • the techniques described herein relate to a solid state composition including: a solid-state coacervate formed by grinding a combination of a freeze-dried silk fibroin and tannic acid in a ratio by weight of silk fibroin protein to tannic acid of between 1 :10 and 100 : 1.
  • the techniques described herein relate to a method of making a solid state composition, the method including: a) grinding together a freeze-dried silk fibroin and tannic acid in a ratio by weight of silk fibroin protein to tannic acid of between 1 :10 and 100:1, thereby forming a solid-state coacervate.
  • Fig. 1 depicts a general preparation method for solid-state coacervates as underwater adhesives.
  • FIG. 2 depicts an overview of the coacervation process.
  • Fig. 3A depicts a schematic representation of the microscopic observation setup for the coacervate.
  • Fig. 3B depicts photographs (top) and micrographs (bottom) of the adhesive at room temperature (left) and after exposure to 60 °C for 15 minutes in a water bath (right).
  • Fig. 3C depicts photographs of the adhesive confined between two coverslips and heated on a hot plate, showing macroscopic water expulsion as a result of heating.
  • Fig. 3D depicts (Left) the experimental setup of a metal soldering probe applied to the adhesive under a microscope and (Right) video frames capturing water expulsion from the adhesive due to localized heating.
  • Fig. 3E depicts a proposed schematic illustrating the potential mechanism of underwater adhesion, emphasizing bulk water removal facilitated by the adhesive’s melting properties and hydration layer removal enabled by the coacervate’s internal water management.
  • Fig. 4A depicts stress-strain curves from tensile testing of the plain coacervate, where the slope indicates the Young’s modulus.
  • Fig. 4B depicts complex modulus of the same material measured through rheological analysis.
  • Fig. 4C depicts long-term tensile performance of the plain coacervate stored in seawater at 8 °C and 20 °C.
  • Fig. 4D depicts one-month tensile performance of a FeCh (10%) coacervate stored in seawater at 8 °C.
  • Fig. 4E depicts schematics (left) and underwater application (right) of a solid-state adhesive tablet.
  • Fig. 5A depicts the performance of SFDA-TA coacervate in dry and underwater conditions.
  • Fig. 5B depicts the performance of SF-TA coacervate in dry and underwater conditions.
  • Fig. 6B depicts the performance of SF-TA solid-state coacervate after 1 day in seawater.
  • Fig. 6C depicts the performance of SF-TA solid-state coacervate after 1 week in seawater.
  • Fig. 6D depicts the performance of SF-TA solid-state coacervate at 60 °C.
  • Fig. 6E summarizes the performance of SF-TA solid-state coacervates after application, after heating, after 1 day in seawater, and after 1 week in seawater.
  • Fig. 7A depicts maximum shear stress and toughness of the solid SF-TA coacervate with 5% CaCE
  • Fig. 7B depicts maximum shear stress and toughness of the solid SF-TA coacervate with 10% CaCE
  • Fig. 7C depicts maximum shear stress and toughness of the solid SF-TA coacervate with 20% CaCE
  • Fig. 7D summarizes maximum shear stress and toughness of the solid SF-TA coacervate with 5% CaCE 10% CaCE and 20% CaCE
  • Fig. 8A depicts performance of SF-TA with 5% dopamine solid-state coacervate after its application.
  • Fig. 8B depicts performance of SF-TA with 5% dopamine after 1 day immersed in artificial seawater.
  • Fig. 8C depicts performance of SF-TA with 5% dopamine after 1 week immersed in artificial sea water.
  • Fig. 9A is a schematic representation of silk fibroin highlighting its
  • Fig. 9B depicts the chemical structure of tannic acid.
  • Fig. 9C depicts iron-catechol complexes and their characteristic light absorption spectra depending on the type of complex.
  • Fig. 9D depicts the process of complex coacervation, where two solutions undergo phase separation to form a dense, immiscible, viscous adhesive fluid.
  • Fig. 9E depicts a photograph showing the adhesion of silk-based coacervates in an underwater environment.
  • Fig. 9F depicts photographs of solid-state silk-based coacervates obtained with different iron compounds and concentrations.
  • Fig. 9G depicts schematics for the production of water-triggered adhesive tablets.
  • Fig. 9H depicts melting behavior of a silk-based coacervate between 25 °C and 45 °C.
  • Fig. 91 depicts temperature-resolved performance of silk-based coacervates.
  • Fig. 9J depicts a plot of tensile stress versus displacement for silk-based coacervates containing FeCh, demonstrating the modulation of performance at specific temperatures.
  • Fig. 9K depicts photographs illustrating the transition of the coacervate from highly cohesive at 25 °C to highly adhesive at 45 °C.
  • Fig. 10A shows adhesion in dry and underwater environments.
  • Fig. 10B shows a photo of lap-shear testing.
  • Fig. 11 shows sea water lap-shear testing of iron (III) complexed coacervates.
  • Fig. 12A shows the mechanical tuning of underwater adhesion with iron (III) compounds.
  • Fig 12B shows the tensile strength of control, 5 pm FezOa, 50 nm Fe2O3, and FeCh adhesives.
  • Fig. 12C shows the flexibility of control, 5 pm Fe ⁇ Oa, 50 nm FeaOa, and FeCh adhesives.
  • Fig. 13A shows underwater adhesion as a function of temperature for SF-TA coacervates.
  • Fig. 13B depicts a photograph of probe tack testing.
  • Fig. 14 shows adhesion of iron (III) coacervate at a) 25 °C, b) 35 °C, and c) under tensile stress.
  • Fig. 15a shows an image of plain coacervate in solution at 37 °C.
  • Fig. 15b shows FeCh coacervate in solution at 37 °C.
  • Fig. 15c shows temperature-resolved tensile testing of the plain coacervate.
  • Fig. 15d shows temperature-resolved tensile testing of the FeCh coacervate.
  • Fig. 16b shows images of 10% FeCh adhesion at different temperatures.
  • Fig. 16c plots a comparison of control, 0.1% FeCh coacervate, and 10% FeCh coacervate adhesion testing at different temperatures.
  • Fig. 16d is a plot showing performance of the coacervates as a function of time.
  • Fig. 17a depicts adhesion of the SF-TA coacervate on various materials.
  • Fig. 17b quantifies adhesion of the SF-TA coacervate on various materials.
  • Fig. 18 shows a schematic to produce water-triggered adhesive tablets.
  • Fig. 19a shows the experimental setup and results of a constant buoyant stress experiment, with CAD design of the GPS holder.
  • Fig. 19b shows the experimental setup and results of a constant buoyant stress experiment, with silicone GPS holder prototype stuck to glass wall with adhesive under constant water flow of 5.3 m/s.
  • Fig. 19c shows the experimental setup and results of a constant buoyant stress experiment, with adhesives used in the experiment.
  • Fig. 19d is a plot showing detachment time under buoyant stress.
  • the term “a” may be understood to mean “at least one”; (ii) the term “or” may be understood to mean “and/or”; (iii) the terms “comprising” and “including” may be understood to encompass itemized components or steps whether presented by themselves or together with one or more additional components or steps; and (iv) the terms “about” and “approximately” are used as equivalents and may be understood to permit standard variation as would be understood by those of ordinary skill in the art; and (v) where ranges are provided, endpoints are included.
  • composition as used herein, may be used to refer to a discrete physical entity that comprises one or more specified components.
  • a composition may be of any form - e.g., gas, gel, liquid, solid, etc.
  • composition may refer to a combination of two or more entities for use in a single embodiment or as part of the same article.
  • the combination of entities result in physical admixture, that is, combination as separate co-entities of each of the components of the composition is possible; however many practitioners in the field may find it advantageous to prepare a composition that is an admixture of two or more of the ingredients in a pharmaceutically acceptable carrier, diluent, or excipient, making it possible to administer the component ingredients of the combination at the same time.
  • the term “substantially” refers to the qualitative condition of exhibiting total or near-total extent or degree of a characteristic or property of interest.
  • One of ordinary skill in the biological arts will understand that biological and chemical phenomena rarely, if ever, go to completion and/or proceed to completeness or achieve or avoid an absolute result.
  • the term “substantially” is therefore used herein to capture the potential lack of completeness inherent in many biological and chemical phenomena.
  • compositions that undergo some chemical transformation during their use can be described in various ways. For instance, dissolving NaCl in water can be described as water having an NaCl concentration or water having a concentration of Na + and CF ions.
  • components of chemical compositions can be described either as the form they take prior to any chemical transformation or the form they take following the chemical transformation.
  • the assumption should be that the component is being described in the context of the particular composition being described (i.e., if describing a finished product or an intermediary after a given chemical transformation, then the chemically transformed entity is being described, and if describing a starting product or intermediary prior to the chemical transformation, then the untransformed entity is being described.
  • the present disclosure relates to adhesive compositions.
  • adhesive compositions are applied in thin layers or films.
  • film refers to a layer of material, either solid or liquid, which has a thickness suitable for use in an adhesive application.
  • Adhesive materials have been integral to the earliest tools crafted by humans, and their significance persists in our market, technology, and society. Throughout history, humans have sought inspiration from the biological realm, observing how animals and plants have developed adhesive mechanisms for survival. Examples include mussel-inspired polymers, gecko feet, and Velcro. Despite significant technological advancements, there remains a notable gap in the field of underwater adhesives. Many marine organisms have evolved the remarkable ability to produce and secrete adhesives derived from water-soluble biological molecules, allowing them to firmly attach to even the hulls of moving ships. Among these organisms, a mechanism that has independently evolved in various species involves the generation of adhesives through complex coacervation.
  • Coacervates are dense, liquid droplets formed when certain colloidal solutions undergo phase separation. This occurs when a solution containing two or more components, such as polymers or macromolecules, initially dissolved or dispersed homogeneously, separate into distinct phases. This phase transition can also be induced with concentrated solutions of biopolymers, which precipitate in an aqueous environment, producing a highly viscous fluid with adhesive properties. This approach has recently gained traction in the scientific community for producing coacervate adhesives using various polymers.
  • the present disclosure identified two primary challenges in developing underwater adhesives: i) avoiding dilution of materials used and ii) accessing surfaces to establish adhesive interactions.
  • Coacervate-based materials were identified as an ideal candidate due to avoiding dilution by leveraging liquid-liquid phase separation to form a macromolecule-rich adhesive material. Additionally, coacervates typically exhibit remarkably low surface tension with water ( ⁇ 1 mJ/m 2 ), enabling them to displace water from surfaces effectively, thus establishing strong adhesive interactions.
  • a mixture of silk fibroin powder and tannic acid powder was selected to formulate the adhesive composition based on biomolecules.
  • An exemplary overview of the process is shown in Fig- 1-
  • the present disclosure provides a solid state composition.
  • the solid state composition includes a coacervate-forming pair of materials including silk fibroin and a silk-complementary material.
  • the silk-complementary material is capable of forming a coacervate with the silk fibroin.
  • the silk fibroin includes silk fibroin powder, and the complementary powder includes the complementary material.
  • the silk fibroin and the silk- complementary material are present in the solid state composition in a weight ratio of between 1 :10 and 100:1. In some cases, the silk fibroin and the silk-complementary material are present in the solid state composition in a weight ratio of between 1:10 and 1:1.
  • the silk fibroin and the silk-complementary material are present in the solid state composition in a weight ratio of between 1 : 1 and 20:1. In some cases, the silk fibroin and the silk-complementary material are present in the solid state composition in a weight ratio of between 20: 1 and 40: 1 . In some cases, the silk fibroin and the silk-complementary material are present in the solid state composition in a weight ratio of between 40:1 and 60: 1. In some cases, the silk fibroin and the silk-complementary material are present in the solid state composition in a weight ratio of between 60: 1 and 80: 1. In some cases, the silk fibroin and the silk-complementary material are present in the solid state composition in a weight ratio of between 80:1 and 100:1.
  • the coacervate may be formed by hydrating and agitating the solid state composition. Hydrating the solid state composition may include mixing with water or an aqueous solution.
  • the aqueous solution may be one of fresh water or sea water. The mixing may occur within a syringe.
  • the silk fibroin powder and the complementary powder may independently have an average particle diameter (D50) of between 1 pm and 100 pm. In some cases, the D50 may be between 1 pm and 10 pm. In some cases, the D50 may be between 10 pm and 25 pm. In some cases, the D50 may be between 25 pm and 50 pm. In some cases, the D50 may be between 50 and 100 pm.
  • the silk fibroin may be a dopamine-substituted silk fibroin.
  • the hydrating and mixing to form the coacervate may be completed in under 5 seconds. In some cases, the hydrating and mixing may be completed in under 4 seconds. In some cases, the hydrating and mixing may be completed in under 3 seconds. In some cases, the hydrating and mixing may be completed in under 2 seconds. In some cases, the hydrating and mixing may be completed in under 1 second.
  • the solid state composition may retain the capacity to form the coacervate after storage for a predetermined storage time and upon contact with an aqueous solvent after the predetermined storage time. The predetermined storage time may be 1 month or more or 1 year or more.
  • the silk fibroin may be freeze-dried silk fibroin.
  • the freeze-dried silk fibroin may be dopamine- substituted silk fibroin.
  • the dopamine substitution may include polydopamine substitution.
  • the present disclosure provides a coacervate-based adhesive composition.
  • the coacervate-based adhesive composition comprises a dense phase of a coacervate.
  • the dense phase of a coacervate is formed by mixing a dopamine-substituted silk fibroin solution and tannic acid.
  • the light phase of the coacervate-based adhesive can be optionally an aqueous solution that contains an unreacted dopamine-substituted silk fibroin and unreacted tannic acid.
  • the coacervate-based adhesive composition wherein the coacervate-based adhesive is optionally substantially free of the light phase.
  • the light phase of the coacervate-based adhesive is the aqueous phase. In certain cases, the coacervate-based adhesive is substantially free of the light phase.
  • This complexing occurs in a fashion understood by those having ordinary skill in the art. A non-limiting description of this complexing and crosslinking is provided in Example 1.
  • the dense phase of a coacervate can be formed by mixing a dopamine- substituted silk fibroin and tannic acid in a ratio by weight between 1:10 and 100:1.
  • the ratio by weight of dopamine-substituted silk fibroin to tannic acid can be at least 1 : 10.
  • the ratio may be at least 1 :5.
  • the ratio may be at least 1:4.
  • the ratio may be at least 1:3.
  • the ratio may be at least 1:2.
  • the ratio may be at least 2:3.
  • the ratio may be at least 3:4.
  • the ratio may be at least 4:5.
  • the ratio may be at least 1:1. In some cases, the ratio may be at least 5:1. In some cases, the ratio may be at least 10: 1. In some cases, the ratio may be at least 15:1. In some cases, the ratio may be at least 20: 1. In some cases, the ratio may be at least 25:1. In some cases, the ratio may be at least 30: 1. In some cases, the ratio may be at least 40: 1. In some cases, the ratio may be at least 50:1. In some cases, the ratio may be or at least 60: 1. In some cases, the ratio by weight of dopamine-substituted silk fibroin to tannic acid can be at most 100: 1. In some cases, the ratio may be at most 90:1. In some cases, the ratio may be at most 80:1.
  • the ratio may be at most 75:1. In some cases, the ratio may be at most 70: 1. In some cases, the ratio may be at most 65:1. In some cases, the ratio may be at most 60: 1. In some cases, the ratio may be at most 50:1. In some cases, the ratio may be at most 45:1. In some cases, the ratio may be at most 40:1. In some cases, the ratio may be at most 30: 1. In some cases, the ratio may be at most 25:1. In some cases, the ratio may be at most 22: 1. In some cases, the ratio may be at most 20: 1. In some cases, the ratio may be at most 15: 1. In some cases, the ratio may be at most 10:1. In some cases, the ratio may be at most 7:1.
  • the ratio may be at most 6:1. In some cases, the ratio may be at most 5:1. In some cases, the ratio may be at most 3 : 1. In some cases, the ratio may be at most 1 : 1. In some cases, the ratio may be at most 1:2.
  • the tannic acid can be present in the adhesive composition in a dry-solids- basis amount by weight relative to the dry-solid-basis amount by weight of the silk fibroin protein and the dopamine of between 0.001% and 1.0%. In some cases, the tannic acid can be present in an amount between 0.005% and 0.9%. In some cases, the tannic acid can be present in an amount between 0.01 % and 0.75%. In some cases, the tannic acid can be present in an amount between 0. 1 % and 0.5%. In some cases, the tannic acid can be present in an amount between 0.025% and 0.25%. In some cases, the tannic acid can be present in an amount between 0.05% and 0.1%.
  • the tannic acid can be present in an amount between 0.25% and 0.85%. In some cases, the tannic acid can be present in an amount between 0.002% and 0.05%. In some cases, the tannic acid can be present in an amount of at least 0.005 mg per 1 mg of dopamine-modified silk fibroin.
  • the coacervate-based adhesive composition contains components that are present in naturally occurring organisms. These components may be covalently or ionically or otherwise linked to one another. In other words, two natural components that present in naturally occurring organisms can be covalently bound to one another and still be defined as a component that is present in naturally occurring organisms. Dopamine-substituted silk fibroin is not known to be present in naturally occurring organisms, but it’s made of components that are present in naturally occurring organisms.
  • the present disclosure provides a method of making coacervate-based adhesive.
  • the method includes mixing a dopamine-substituted silk firoin solution and tannic acid in a ratio by weight for dopamine-substituted silk fibroin to tannic acid between 1: 10 and 100:1 or one of the aforementioned ratios identified above.
  • the mixing thereby forming a coacervate.
  • the coacervate can comprise a dense phase and a light phase.
  • the dense phase of a coacervate is formed by mixing a dopamine-substituted silk fibroin solution and tannic acid and the light phase of the coacervate-based adhesive can be optionally an aqueous solution that contains an unreacted dopamine-substituted silk fibroin and unreacted tannic acid.
  • the light phase of the coacervate-based adhesive is the aqueous phase.
  • the coacervate-based adhesive is substantially free of the light phase.
  • the method includes removing at least a portion of the light phase from the coacervate. In some cases, the method includes optionally isolating at least a portion of the dense phase from the light phase.
  • a method of making a solid state composition includes grinding together a freeze-dried silk fibroin and tannic acid in a ratio by weight of silk fibroin protein to tannic acid of between 1 :10 and 100:1 or one of the aforementioned ratios identified above, thereby forming a solid-state coacervate.
  • the method may also include contacting the solid state composition with an aqueous solvent to obtain the coacervate-based adhesive.
  • the ratio of silk fibroin protein to tannic acid may be substantially 1:1.
  • the solid state composition may be preheated prior to its application.
  • the method of making the coacervate-based adhesive includes a mass ratio of tannic acid to silk fibroin that is substantially 1 :1.
  • the coacervate-based adhesive or the method of forming or using the coacervate-based adhesive comprises a dry adhesive strength that is greater than a first comparison dry adhesive strength.
  • the first comparison dry adhesive strength is from a first comparison coacervate-based adhesive that replaces the dopamine-substituted silk fibroin solution with an unmodified silk fibroin solution and is otherwise identical to the coacervate-based adhesive.
  • the dry adhesive strength can be 5% greater.
  • the dry adhesive strength can be 10% greater than the first comparison dry adhesive strength.
  • the dry adhesive strength can be 25% greater than the first comparison dry adhesive strength.
  • the dry adhesive strength can be 50% greater than the first comparison dry adhesive strength. In some aspects, the dry adhesive strength can be 75% greater than the first comparison dry adhesive strength. In some aspects, the dry adhesive strength can be 100% greater than the first comparison dry adhesive strength. In some cases, the dry adhesive strength is at least 500 kPa. In some cases, the dry adhesive strength is at least 750 kPa. In some cases, the dry adhesive strength is at least 1 MPa. In some cases, the dry adhesive strength is at least 2 MPa. In some cases, the dry adhesive strength is at least 3 MPa. In some cases, the dry adhesive strength is at least 5 MPa.
  • the composition or method comprises the coacervate-based adhesive which has a wet adhesive strength that is greater than a first comparison wet adhesive strength.
  • the first comparison wet adhesive strength is from a first comparison coacervate-based adhesive that replaces the dopamine-substituted silk fibroin solution with an unmodified silk fibroin solution and is otherwise identical to the coacervate-based adhesive.
  • the wet adhesive strength can be 5% greater than the first comparison wet adhesive strength.
  • the wet adhesive strength can be 10% greater than the first comparison wet adhesive strength.
  • the wet adhesive strength can be 25% greater than the first comparison wet adhesive strength.
  • the wet adhesive strength can be 50% greater than the first comparison wet adhesive strength. In some cases, the wet adhesive strength can be 75% greater than the first comparison wet adhesive strength. In some cases, the wet adhesive strength can be 100% greater than the first comparison wet adhesive strength. In some cases, the wet adhesive strength can be at least 200 kPa. In some cases, the wet adhesive strength can be at least 500 kPa. In some cases, the wet adhesive strength can be at least 750 kPa. In some cases, the wet adhesive strength can be at least 1 MPa. In some cases, the wet adhesive strength can be at least 2 MPa.
  • the composition or method comprises the coacervate-based adhesive which has a dry adhesive strength that is greater than a second comparison dry adhesive strength.
  • the second comparison dry adhesive strength is from a first comparison coacervate-based adhesive that replaces the dopamine-substituted silk fibroin solution with a polyethylene glycol solution and is otherwise identical to the coacervate-based adhesive.
  • the dry adhesive strength can be at least 25% of the second comparison dry adhesive strength.
  • the dry adhesive strength can be at least 50% of the second comparison dry adhesive strength.
  • the dry adhesive strength can be at least 75% of the second comparison dry adhesive strength.
  • the dry adhesive strength can be at least 100% of the second comparison dry adhesive strength.
  • the dry adhesive strength can be at least 125% of the second comparison dry adhesive strength.
  • the composition or method comprises the coacervate-based adhesive which has a wet adhesive strength that is greater than a second comparison wet adhesive strength.
  • the second comparison wet adhesive strength is from a first comparison coacervate-based adhesive that replaces the dopamine-substituted silk fibroin solution with a polyethylene glycol solution and is otherwise identical to the coacervate-based adhesive.
  • the wet adhesive strength can be at least 25% of the second comparison wet adhesive strength.
  • the wet adhesive strength can be at least 50% of the second comparison wet adhesive strength.
  • the wet adhesive strength can be at least 75% of the second comparison wet adhesive strength.
  • the wet adhesive strength can be at least 100% of the second comparison wet adhesive strength.
  • the wet adhesive strength can be at least 125% of the second comparison wet adhesive strength.
  • the second comparison wet adhesive strength is from a first comparison solid state composition that has not been immersed in an aqueous environment for at least 18 hours and is otherwise identical to the solid state composition.
  • the wet adhesive strength may be at least 100 times greater than the second comparison wet adhesive strength.
  • the wet adhesive strength may be at least 75 times greater than the second comparison wet adhesive strength.
  • the wet adhesive strength may be at least 50 times greater than the second comparison wet adhesive strength.
  • the wet adhesive strength may be at least 20 times greater than the second comparison wet adhesive strength.
  • the wet adhesive strength may be at least 10 times greater than the second comparison wet adhesive strength.
  • the solid state composition includes dopamine and has a wet adhesive duration that may be longer than a second comparison wet adhesive duration.
  • the second comparison wet adhesive duration may be from a first comparison solid state composition that does not include dopamine and is otherwise identical to the solid state composition.
  • the wet adhesive duration may be at least 10 times longer than the second comparison wet adhesive strength.
  • the wet adhesive duration may be at least 7 times longer than the second comparison wet adhesive strength.
  • the wet adhesive duration may be at least 5 times longer than the second comparison wet adhesive strength.
  • the wet adhesive duration may be at least 3 times longer than the second comparison wet adhesive strength.
  • the wet adhesive duration may be at least 2 times longer than the second comparison wet adhesive strength.
  • these comparisons are believed to be applicable across a broad range of surfaces for adhering together, but they are particularly true for surfaces that are challenging for adhesion (e.g., adhering to shark skin).
  • the comparative values it is believed that the values hold for the vast majority of surfaces and the compositions disclosed herein provide superior performance over the comparison compositions.
  • the absolute adhesion strength values it is possible that the values may vary based on the surfaces or articles being adhered and a skilled artisan would recognize that the disclosed absolute values may be for a more limited set of surfaces.
  • the adhesive strength may vary depending on the specific aqueous conditions and a skilled artisan would recognize that the presence of certain ions may enhance the adhesive strength.
  • the adhesive strength can be much higher than those discussed elsewhere herein, including peel strengths of greater than 1 N/mm, greater than 2 N/mm, or higher, with as high as 5 N/mm expected to be achievable with certain surfaces.
  • compositions described herein provided other unexpected results.
  • two-component epoxy resins are the state-of-the-art for repairing cracks in marine environments (e.g., swimming pools and the like).
  • these products have a slow setting time and become rigid after curing.
  • they have been shown ineffective on biological tissues (by way of experiments on sharks and manatees), potentially due to the skin irritation.
  • the inventors have discovered a composition that does not require curing time to be adhesive.
  • inventive compositions described herein can remain flexible long after application, which makes them compatible with an animal’s movements while maintaining adhesion.
  • the solid-state format of the coacervate offers several advantages. It provides a significantly extended shelf life, with minimal storage requirements, mainly protection from water.
  • the coacervate can be conveniently stored in a device, such as a syringe, and is readily accessible for use without the need for specialized training, approaching commercial product standards.
  • the powder format both allows easy handling of the adhesive and permits the inclusion of other reactive additives that can enhance or adjust the adhesive properties of the coacervate.
  • the coacervate itself is dried and stored as a powder it crumbles, rendering it ineffective for dry applications.
  • the composition or method of making the coacervate-based adhesive comprises the polydopamine-substituted silk fibroin.
  • the polydopamine-substituted silk fibroin has a degree of polydopamine-substitution of between 5% and 50%. In some cases, the degree of polydopamine-substitution may be between 10% and 40%. In some cases, the degree of polydopamine-substitution may be between 25% and 35%. The degree of polydopamine-substitution is measured as a percentage by weight of polydopamine substituents related to the weight of the silk fibroin backbone.
  • the polydopamine-substituted silk fibroin is polydopamine- substituted at one or more target amino acids.
  • the one or more target amino acids are selected from the group consisting of cysteine, tyrosine, arginine, lysine, histidine, phenylalinine, proline, and combinations thereof.
  • the polydopamine-substituted silk fibroin is polydopamine- substituted at one or more tyrosines.
  • polydopamine-substituted silk fibroin is the substituted with poly dopamine having 15 polymeric units or less. In some cases, the polydopamine has 13 polymeric units or less.
  • the polydopamine has 12 polymeric units or less. In some cases, the polydopamine has 10 polymeric units or less. In some cases, the polydopamine has 9 polymeric units or less. In some cases, the polydopamine has 8 polymeric units or less.
  • the silk fibroin backbone of the polydopamine-substituted silk fibroin can have a weight average molecular weight of between 25 kDa and 150 kDa.
  • the silk fibroin backbone can have a weight average molecular weight of between 30 kDa and 125 kDa.
  • the silk fibroin backbone can have a weight average molecular weight of between 35 kDa and 100 kDa.
  • the silk fibroin backbone can have a weight average molecular weight of between 25 kDa and 75 kDa.
  • the silk fibroin backbone can have a weight average molecular weight of between 100 kDa and 150 kDa. In some cases, the silk fibroin backbone can have a weight average molecular weight of between 50 kDa and 125 kDa. In some cases, the silk fibroin backbone can have a weight average molecular weight of between 40 kDa and 90 kDa. In some cases, the silk fibroin backbone can have a weight average molecular weight of between 55 kDa and 105 kDa. In some cases, the silk fibroin backbone can have a weight average molecular weight of between 45 kDa and 65 kDa.
  • the silk fibroin backbone of the polydopamine-substituted silk fibroin can have a number average molecular weight of between 25 kDa and 150 kDa.
  • the silk fibroin backbone can have a number average molecular weight of between 30 kDa and 125 kDa.
  • the silk fibroin backbone can have a number average molecular weight of between 35 kDa and 100 kDa.
  • the silk fibroin backbone can have a number average molecular weight of between 25 kDa and 75 kDa.
  • the silk fibroin backbone can have a number average molecular weight of between 100 kDa and 150 kDa. In some cases, the silk fibroin backbone can have a number average molecular weight of between 50 kDa and 125 kDa. In some cases, the silk fibroin backbone can have a number average molecular weight of between 40 kDa and 90 kDa. In some cases, the silk fibroin backbone can have a number average molecular weight of between 55 kDa and 105 kDa. In some cases, the silk fibroin backbone can have a number average molecular weight of between 45 kDa and 65 kDa.
  • the composition or method of making the coacervate-based adhesive comprises the polydopamine-substituted silk fibroin which is made by mixing silk fibroin with soluble dopamine in an aqueous solution.
  • the polydopamine-substituted silk fibroin has a structure that is indistinguishable from a comparison structure that is made by mixing comparison silk fibroin with comparison soluble dopamine in a comparison aqueous solution.
  • the soluble dopamine and/or the comparison soluble dopamine is dopamine hydrochloride.
  • the composition or method of making the coacervate-based adhesive comprises mixing silk fibroin with soluble dopamine in an aqueous solution.
  • the mixing of silk fibroin with soluble dopamine in an aqueous solution uses a ratio by weight of silk fibroin to soluble polydopamine of between 1 :2 and 10: 1.
  • the ratio may be between 1:1 and 5:1.
  • the ratio may be between 1.25:1 and 3:1.
  • the ratio may be at least 1:2.
  • the ratio may be at least 1.5:1.
  • the ratio may be at least 1:1.
  • the ratio may be at least 1.1: 1.
  • the ratio may be at least 1.2: 1.
  • the ratio may be at least 1.25: 1. In some aspects, the ratio may be at least 1.3:1. In some aspects, the ratio may be at least 1.4: 1. In some aspects, the ratio may be at least 1.5:1. In some aspects, the ratio may be at least 1.75:1. In some aspects, the ratio may be at least 2:1. In some aspects, the ratio may be at least 3:1. In some aspects, the ratio may be or at least 4:1. In some aspects, the ratio may be at most 10: 1. In some aspects, the ratio may be at most 9: 1. In some aspects, the ratio may be at most 8:1. In some aspects, the ratio may be at most 7:1. In some aspects, the ratio may be at most 6:1. In some aspects, the ratio may be at most 5:1. In some aspects, the ratio may be at most 4:1. In some aspects, the ratio may be at most 3:1. In some aspects, the ratio may be at most 2: 1. In some aspects, the ratio may be or at most 1 :1.
  • the composition or method of making the coacervate-based adhesive comprises mixing comparison silk fibroin with comparison soluble polydopamine in a comparison aqueous solution.
  • the mixing of comparison silk fibroin with comparison soluble polydopamine uses a ratio by weight of comparison silk fibroin to comparison soluble polydopamine of between 1 :2 and 10:1.
  • the ratio may be between 1 :1 and 5:1.
  • the ratio may be between 1.25:1 and 3:1.
  • the ratio may be at least 1 :2.
  • the ratio may be at least 1.5:1.
  • the ratio may be at least 1:1.
  • the ratio may be at least 1.1:1.
  • the ratio may be at least 1.2: 1. In some aspects, the ratio may be at least 1.25: 1. In some aspects, the ratio may be at least 1.3:1. In some aspects, the ratio may be at least 1.4: 1. In some aspects, the ratio may be at least 1.5:1. In some aspects, the ratio may be a least 1.75:1. In some aspects, the ratio may be at least 2:1. In some aspects, the ratio may be at least 3 : 1. In some aspects, the ratio may be at least 4: 1. In some aspects, the ratio may be at most 10: 1. In some aspects, the ratio may be at most 9:1. In some aspects, the ratio may be at most 8:1. In some aspects, the ratio may he at most 7:1. In some aspects, the ratio may he at most 6:1. In some aspects, the ratio may be at most 5:1. In some aspects, the ratio may be at most 4:1. In some aspects, the ratio may be at most 3:1. In some aspects, the ratio may be at most 2:1. In some aspects, the ratio may be at most 1:1.
  • the solid state composition (e.g., powder) may be compressed into a tablet form, solid state tablet, or similar solid individual unit form using a mold and applying a pressure.
  • the pressure can be applied at between 0.001 MPa and 5 MPa. In some cases, the applied pressure is at least 0.001 MPa. In some cases, the applied pressure is at least 0.01 MPa. In some cases, the applied pressure is at least 0. 1 MPa. In some cases, the applied pressure is at or at least 1 MPa. In some cases, the applied pressure is at most 5 MPa. In some cases, the applied pressure is at most 2 MPa. In some cases, the applied pressure is at most 0.5 MPa. In some cases, the applied pressure is at most 0.05 MPa. In some cases, the applied pressure is at most 0.005 MPa.
  • additives may be added to the solid state composition (e.g., powder) at between 10% and 80% of tablet weight.
  • the additive can be present in the solid state composition in an amount by weight of at least 10%.
  • the additive can be present in the solid state composition in an amount by weight of at least 30%.
  • the additive can be present in the solid state composition in an amount by weight of at least 50%.
  • the additive can be present in the solid state composition in an amount by weight of at least 70%.
  • the additive can be present in the powder in an amount by weight of at most 80%.
  • the additive can be present in the solid state composition in an amount by weight of at most 60%.
  • the additive can be present in the solid state composition in an amount by weight of at most 40%. In some cases, the additive can be present in the solid state composition in an amount by weight of at most 20%.
  • the additives may accelerate the dissolution of the tablet into adhesive upon contact with fresh or salt water.
  • the additive can be or can include one or more gas-evolving molecules.
  • suitable gas-evolving molecules include, but are not limited to succinic acid, sodium carbonate, carbonic acid, bicarbonates, sulfites, bisulfites, ammonium chloride, nitrites, chlorates, peroxides, oxalic acid, or azides.
  • the additive can be or can include one or more salts that produce exothermic reactions with water.
  • suitable salts that produce exothermic reactions with water include, but are not limited to, magnesium chloride, calcium chloride, aluminum chloride, sodium hydroxide, potassium hydroxide.
  • the additive can be or can include one or more hydrogen bonding disrupters.
  • suitable hydrogen bonding disruptors include, but are not limited to, urea, 1 ,6-hexanediol, ethanol or guanidium chloride. Without wishing to be bound by any particular theory, it is believed that the hydrogen bonding disrupters would lower the glass transition temperature of the adhesive material, lowering the temperature of adhesion.
  • the present disclosure provides a method of using the coacervate-based adhesive.
  • the method comprises contacting a first article and a second article together with an adhesive amount of the coacervate-based adhesive, thereby adhering the first and second articles to one another.
  • the first article can be an animal, such as a marine animal, such as a fish or a marine mammal.
  • the second article can be a tag, such as a numbered tag, an electronic tag (e.g., radio transmitters), a water-permeable tag, or another sensor that can be usefully applied to a marine animal or other article.
  • the first and/or second article can be water permeable, thereby allowing water to interact with the adhesive via penetration of the second article.
  • the second article can include an electronic component.
  • a delivery device or a syringe can include the solid state composition of or made by the methods described herein.
  • the present disclosure provides a method of using the solid state composition including contacting the solid state composition with an aqueous solvent within a delivery device or syringe to obtain a coacervate-based adhesive and dispensing the coacervate-based adhesive from the delivery device or syringe onto at least one surface of a first or second article and contacting the first and second articles together with the coacervate-based adhesive on the at least one surface, thereby adhering the first and second articles to one another.
  • the contacting can be completed in under 5 seconds. In some cases, the contacting can be completed in under 4 seconds.
  • the solid state composition may further include an additive.
  • the additive mass may be between 10% and 80% of the mass of the solid state composition. In some cases, the additive mass may be at least 10% of the mass of the solid state composition. In some cases, the additive mass may be at least 30% of the mass of the solid state composition. In some cases, the additive mass may be at least 50% of the mass of the solid state composition. In some cases, the additive mass may be at least 70% of the mass of the solid state composition. In some cases, the additive mass may be at most 80% of the mass of the solid state composition.
  • the additive mass may be at most 60% of the mass of the solid state composition. In some cases, the additive mass may be at most 40% of the mass of the solid state composition. In some cases, the additive mass may be at most 20% of the mass of the solid state composition.
  • the additive may comprise a gas-evolving molecule or a salt that produces an exothermic reaction as described herein.
  • the adhesives described herein can be used to adhere tags to marine animals, such as sharks.
  • marine animals such as sharks.
  • the examples below show testing to establish adequate adhesion with the very challenging surface of shark skin. Without wishing to be bound by any particular theory, it is believed that achieving adequate adhesion to shark skin is a baseline adhesion performance that can be broadly applied to other marine species with reasonable predictability (i.e., if it works on shark skin, it likely works on the exterior surface of most other species).
  • compositions could be useful as drug delivery systems for antibiotics or medications. They could be used to treat wounds in at-risk species, allowing for controlled release of therapeutic agents embedded therein. As yet another example, the compositions could be useful in fish farms.
  • the method of using can provide an adhesive strength that withstands shear forces and does not require curing.
  • the method of using can provide instantaneous adhesion following underwater application. In some cases, the adhesive strength grows over time following application to a final adhesive strength.
  • the solid state composition provides adhesion between two articles when submerged in at least one of simulated sea water or distilled water.
  • the method of using the coacervate-based adhesive includes maintaining the adhesive at a low temperature (e.g., below 15 °C, below 10 °C, below 5 °C, etc.) to control the viscosity of the adhesive and retain structural integrity of the adhesive in a desired shape. This lowered temperature may reduce the surface tackiness of the adhesive making it easier to handle.
  • the method can include raising the temperature of the adhesive following the contacting.
  • silk fibroin powder and tannic acid powder may be combined to form an adhesive coacervate. The powders may be ground together or otherwise combined with reduced particle sizes relative to the starting material. The coacervate may absorb between 25% and 200% of its weight in water.
  • the coacervate may absorb at least 25% of its weight in water. In some cases, the coacervate may absorb at least 50% of its weight in water. In some cases, the coacervate may absorb at least 100% of its weight in water. In some cases, the coacervate may absorb at least 150% of its weight in water. In some cases, the coacervate may absorb at most 200% of its weight in water. In some cases, the coacervate may absorb at most 175% of its weight in water. In some cases, the coacervate may absorb at most 125% of its weight in water. In some cases, the coacervate may absorb at most 100% of its weight in water.
  • the coacervate may absorb at most 75% of its weight in water. In some cases, the coacervate may absorb or at most 50% of its weight in water.
  • the adhesive may have vesicles between 10 pm and 100 pm when placed underwater. The vesicles may contain water. The vesicles may be expelled upon heating and reabsorbed upon cooling. The mechanical performance of the adhesive may change with changing conditioning temperatures. The adhesive strength of the adhesive may increase over time underwater. [0131] It should be apparent to those skilled in the art that many additional modifications beside those already described are possible without departing from the inventive concepts. In interpreting this disclosure, all terms should be interpreted in the broadest possible manner consistent with the context.
  • silks there are many different silks, however, including spider silk (e.g., obtained from Nephila clavipes), transgenic silks, genetically engineered silks, such as silks from bacteria, yeast, mammalian cells, transgenic animals, or transgenic plants, and variants thereof, that can be used. See, e.g., WO 97/08315 and U.S. Pat. No. 5,245,012, each of which is incorporated herein by reference in their entireties.
  • spider silk e.g., obtained from Nephila clavipes
  • transgenic silks e.g., obtained from Nephila clavipes
  • genetically engineered silks such as silks from bacteria, yeast, mammalian cells, transgenic animals, or transgenic plants, and variants thereof, that can be used. See, e.g., WO 97/08315 and U.S. Pat. No. 5,245,012, each of which is incorporated herein by reference in their entireties.
  • a variety of functionalizing agents may be used with the silk-containing embodiments described herein (e.g., silk membrane, silk composition, silk articles, silk matrix, silk foam, silk microsphere, liquid composition, whipped silk cream, silk meringue, compressed silk meringue, hot-pressed silk meringue, silk leather, silk powder, silk toner, edible silkbased films, etc.). It should be understood that the examples herein may recite one or a few silkcontaining embodiments but are applicable to any silk-containing embodiment, as applicable.
  • a functionalizing agent may be any compound or molecule that facilitates the attachment to and/or development (e.g., growth) of one or more endothelial cells on a silk membrane.
  • a functionalizing agent may be or comprise a cell attachment mediator and/or an extracellular matrix protein, for example: collagen (e.g., collagen type I, collagen type III, collagen type IV or collagen type VI), elastin, fibronectin, vitronectin, laminin, fibrinogen, von Willebrand factor, proteoglycans, decorin, perlecan, nidogen, hyaluronan, and/or peptides containing known integrin binding domains e.g. “RGD” integrin binding sequence, or variations thereof, that are known to affect cellular attachment.
  • collagen e.g., collagen type I, collagen type III, collagen type IV or collagen type VI
  • elastin e.g., fibronectin, vitronectin, laminin, fibrinogen, von Willebrand factor, proteoglycans, decorin, perlecan, nidogen, hyaluronan
  • peptides containing known integrin binding domains e
  • a functionalizing agent may be any soluble molecule produced by endothelial cells.
  • Non-limiting examples include fibroblast growth factor- 1 (FGF1) and vascular endothelial growth factors (VEGF).
  • compositions may comprise the use of laminin, fibronectin and/or fibrinogen, and type IV collagen in order to facilitate the attachment and growth of endothelial cells on a silk membrane (e.g., a porous silk membrane) and/or attachment of megakaryocytes to a silk matrix.
  • a silk membrane e.g., a porous silk membrane
  • a functionalizing agent may be embedded or otherwise associated with a silk membrane and/or silk matrix such that at least a portion of the functionalizing agent is surrounded by a silk membrane and/or silk matrix as contrasted to a functionalizing agent simply being positioned along the surface of a silk membrane and/or silk matrix.
  • a functionalizing agent is distributed along and/or incorporated in substantially the entire surface area of a silk membrane/silk wall.
  • a functionalizing agent is distributed and/or incorporated only at one or more discrete portions of a silk membrane/wall and/or silk matrix.
  • a functionalizing agent is distributed in and/or along at least one of the lumenfacing side of a silk wall and the matrix-facing side of a silk wall.
  • any application-appropriate amount of one or more functionalizing agents may be used.
  • the amount of an individual functionalizing agent may be between about 1 pg/ml and 1,000 pg/ml (e.g., between about 2 and 1,000, 5 and 1,000, 10 and 1,000, 10 and 500, 10 and 100 pg/ml).
  • the amount of an individual functionalizing agent may be at least 1 pg/ml (e.g., at least 5, 10, 15, 20 25, 50, 100, 200, 300 400, 500, 600, 700, 800, or 900 pg/ml ).
  • the composition comprises one or more sensing agents, such as a sensing dye.
  • the sensing agents/sensing dyes are environmentally sensitive and produce a measurable response to one or more environmental factors.
  • the environmentally- sensitive agent or dye may be present in the composition in an effective amount to alter the composition from a first chemical-physical state to a second chemical-physical state in response to an environmental parameter (e.g., a change in pH, light intensity or exposure, temperature, pressure or strain, voltage, physiological parameter of a subject, and/or concentration of chemical species in the surrounding environment) or an externally applied stimulus (e.g., optical interrogation, acoustic interrogation, and/or applied heat).
  • an environmental parameter e.g., a change in pH, light intensity or exposure, temperature, pressure or strain, voltage, physiological parameter of a subject, and/or concentration of chemical species in the surrounding environment
  • an externally applied stimulus e.g., optical interrogation, acoustic interrogation, and/or applied heat.
  • Exemplary light responsive dyes or agents include, but are not limited to, photochromic compounds or agents, such as triarylmethanes, stilbenes, azastilbenes, nitrones, fulgides, spiropyrans, napthopyrans, spiro-oxazines, quinones, derivatives, and combinations thereof.
  • Exemplary potentiometric dyes include, but are not limited to, substituted amiononaphthylehenylpridinium (ANEP) dyes, such as di-4-ANEPPS, di-8-ANEPPS, and N-(4- Sulfobutyl)-4-(6-(4-(Dibutylamino)phenyl)hexatrienyl)Pyridinium (RH237).
  • ANEP substituted amiononaphthylehenylpridinium
  • Exemplary temperature sensitive dyes or agents include, but are not limited to, thermochromic compounds or agents, such as thermochromic liquid crystals, leuco dyes, fluoran dyes, octadecylphosphonic acid.
  • Exemplary pressure or strain sensitive dyes or agents include, but are not limited to, spiropyran compounds and agents.
  • chemi-sensitive dyes or agents include, but are not limited to, antibodies such as immunoglobulin G (IgG) which may change color from blue to red in response to bacterial contamination.
  • IgG immunoglobulin G
  • Exemplary flavorants include ester flavorants, amino acid flavorants, nucleic acid flavorants, organic acid flavorants, and inorganic acid flavorants, such as, but not limited to, diacetyl, acetyl propionyl, acetoin, isoamyl acetate, benzaldehyde, cinnamaldehyde, ethyl propionate, methyl anthranilate, limonene, ethyl decadienoate, allyl hexanoate, ethyl maltol, ethylvanillin, methyl salicylate, manzanate, glutamic acid salts, glycine salts, guanylic acids salts, inosinic acid salts, acetic acid, ascorbic acid, citric acid, fumaric acid, lactic acid, malic acid, phosphoric acid, tartaric acid, derivatives, and mixtures thereof.
  • diacetyl acetyl propion
  • the additive or dopant comprises an aroma compound.
  • aroma compounds include ester aroma compounds, terpene aroma compounds, cyclic terpenes, and aromatic aroma compounds, such as, but not limited to, geranyl acetate, methyl formate, methyl acetate, methyl propionate, methyl butyrate, ethyl acetate, ethyl butyrate, isoamyl acetate, pentyl butyrate, pentyl pentanoate, octyl acetate, benzyl acetate, methyl anthranilate, myrcene, geraniol, nerol, citral, citronellal, cironellol, linalool, nerolidol, limonene, camphor, menthol, carone, terpineol, alpha-ionone, thujone, eucalyptol, benzaldehy
  • the additive or dopant comprises a colorant, such as a dye or pigment.
  • the dye or pigment imparts a color or grayscale to the composition.
  • the colorant can be different than the sensing agents and/or sensing dyes below. Any organic and/or inorganic pigments and dyes can be included in the inks.
  • Exemplary pigments suitable for use in the present disclosure include International Color Index or C.I. Pigment Black Numbers 1 , 7, 1 1 and 31, C.I. Pigment Blue Numbers 15, 15:1, 15:2, 15:3, 15:4, 15:6, 16, 27, 29, 61 and 62, C.I. Pigment Green Numbers 7, 17, 18 and 36, C.I. Pigment Orange Numbers 5, 13, 16, 34 and 36, C.I.
  • the classes of dyes suitable for use in present invention can be selected from acid dyes, natural dyes, direct dyes (either cationic or anionic), basic dyes, and reactive dyes.
  • the acid dyes also regarded as anionic dyes, are soluble in water and mainly insoluble in organic solvents and are selected, from yellow acid dyes, orange acid dyes, red acid dyes, violet acid dyes, blue acid dyes, green acid dyes, and black acid dyes.
  • European Patent 0745651 incorporated herein by reference, describes a number of acid dyes that are suitable for use in the present disclosure.
  • Exemplary yellow acid dyes include Acid Yellow 1 International Color Index or C.I. 10316); Acid Yellow 7 (C.I. 56295); Acid Yellow 17 (C.I. 18965); Acid Yellow 23 (C.I. 19140); Acid Yellow 29 (C.I. 18900); Acid Yellow 36 (C.I. 13065); Acid Yellow 42 (C.I.
  • Exemplary orange acid dyes include Acid Orange 1 (C.I. 13090/1); Acid Orange 10 (C.I. 16230); Acid Orange 20 (C.I. 14603); Acid Orange 76 (C.I. 18870); Acid Orange 142; Food Orange 2 (C.I. 15980); and Orange B.
  • Exemplary red acid dyes include Acid Red 1 (C.I. 18050); Acid Red 4 (C.I. 14710); Acid Red 18 (C.I. 16255); Acid Red 26 (C.I. 16150); Acid Red 27 (C.I.
  • Acid Red 51 (C.I. 45430, available from BASF Corporation, Mt. Olive, N.J.); Acid Red 52 (C.I. 45100); Acid Red 73 (C.I. 27290); Acid Red 87 (C.I. 45380); Acid Red 94 (C.I. 45440) Acid Red 194; and Food Red 1 (C.I. 14700).
  • Exemplary violet acid dyes include Acid Violet 7 (C.I. 18055); and Acid Violet 49 (C.I. 42640).
  • Exemplary blue acid dyes include Acid Blue 1 (C.I. 42045); Acid Blue 9 (C.I. 42090); Acid Blue 22 (C.I. 42755); Acid Blue 74 (C.I. 73015); Acid Blue 93 (C.I.
  • Exemplary green acid dyes include Acid Green 1 (C.I. 10028); Acid Green 3 (C.I. 42085); Acid Green 5 (C.I. 42095); Acid Green 26 (C.I. 44025); and Food Green 3 (C.I. 42053).
  • Exemplary black acid dyes include Acid Black 1 (C.I. 20470); Acid Black 194 (Basantol® X80, available from BASF Corporation, an azo/1 :2 CR-complex.
  • Exemplary direct dyes for use in the present disclosure include Direct Blue 86 (C.I. 74180); Direct Blue 199; Direct Black 168; Direct Red 253; and Direct Yellow 107/132 (C.I. Not Assigned).
  • Exemplary natural dyes for use in the present disclosure include Alkanet (C.I.
  • Exemplary reactive dyes for use in the present disclosure include Reactive Yellow 37 (monoazo dye); Reactive Black 31 (diazo dye); Reactive Blue 77 (phthalo cyanine dye) and Reactive Red 180 and Reactive Red 108 dyes. Suitable also are the colorants described in The Printing Ink Manual (5th ed., Leach et al. eds. (2007), pages 289-299). Other organic and inorganic pigments and dyes and combinations thereof can be used to achieve the colors desired.
  • the amount of pigment/dye generally is present in an amount of from at or about 0.1 wt% to at or about 20 wt% based on the weight of the composition.
  • a non-white ink can include 15 wt% or less pigment/dye, or 10 wt% or less pigment/dye or 5 wt% pigment/dye, or 1 wt% pigment/dye based on the weight of the composition.
  • a non-white ink can include 1 wt% to 10 wt%, or 5 wt% to 15 wt%, or 10 wt% to 20 wt% pigment/dye based on the weight of the composition.
  • a non-white ink can contain an amount of dye/pigment that is 1 wt%, 2 wt%, 3 wt%, 4 wt%, 5%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15%, 16 wt%, 17 wt%, 18 wt%, 19 wt% or 20 wt% based on the weight of the composition.
  • the amount of white pigment generally is present in an amount of from at or about 1 wt% to at or about 60 wt% based on the weight of the composition. In some applications, greater than 60 wt% white pigment can be present.
  • Preferred white pigments include titanium dioxide (anatase and rutile), zinc oxide, lithopone (calcined coprecipitate of barium sulfate and zinc sulfide), zinc sulfide, blanc fixe and alumina hydrate and combinations thereof, although any of these can be combined with calcium carbonate.
  • a white ink can include 60 wt% or less white pigment, 55 wt% or less white pigment, 50 wt% white pigment, 45 wt% white pigment, 40 wt% white pigment, 35 wt% white pigment, 30 wt% white pigment, 25 wt% white pigment, 20 wt% white pigment, 15 wt% white pigment, or 10 wt% white pigment, based on the weight of the composition.
  • a white ink can include 5 wt% to 60 wt%, 5 wt% to 55 wt%, 10 wt% to 50 wt%, 10 wt% to 25 wt%, 25 wt% to 50 wt%, 5 wt% to 15 wt%, or 40 wt% to 60 wt% white pigment based on the weight of the composition.
  • a non-white ink can an amount of dye/pigment that is 5%, 6 wt%, 7 wt%, 8 wt%, 9 wt%, 10 wt%, 11 wt%, 12 wt%, 13 wt%, 14 wt%, 15%, 16 wt%, 17 wt%, 18 wt%, 19 wt%, 20 wt%, 21 wt%, 22 wt%, 23 wt%, 24 wt%, 25%, 26 wt%, 27 wt%, 28 wt%, 29 wt%, 30 wt%, 31 wt%, 32 wt%, 33 wt%, 34 wt%, 35%, 36 wt%, 37 wt%, 38 wt%, 39 wt%, 40 wt%, 41 wt%, 42 wt%, 43 wt%, 44 wt%, 45%, 46 wt%
  • the additive or dopant comprises a conductive additive.
  • exemplary conductive additives include, but are not limited to graphite, graphite powder, carbon nanotubes, and metallic particles or nanoparticles, such as gold nanoparticles.
  • the conductive additive is biocompatible and non-toxic.
  • the additive is a biologically active agent.
  • biologically active agent refers to any molecule which exerts at least one biological effect in vivo.
  • the biologically active agent can be a therapeutic agent to treat or prevent a disease state or condition in a subject.
  • Biologically active agents include, without limitation, organic molecules, inorganic materials, proteins, peptides, nucleic acids (e.g., genes, gene fragments, gene regulatory sequences, and antisense molecules), nucleoproteins, polysaccharides, glycoproteins, and lipoproteins.
  • Classes of biologically active compounds that can be incorporated into the composition provided herein include, without limitation, anticancer agents, antibiotics, analgesics, antiinflammatory agents, immunosuppressants, enzyme inhibitors, antihistamines, anti-convulsants, hormones, muscle relaxants, antispasmodics, ophthalmic agents, prostaglandins, anti-depressants, anti-psychotic substances, trophic factors, osteoinductive proteins, growth factors, and vaccines.
  • active agent may also be used herein to refer to a biological sample (e.g., a sample of tissue or fluid, such as for instance blood) or a component thereof, and/or to a biologically active entity or compound, and/or to a structurally or functionally labile entity.
  • Exemplary active agents include, but are not limited to, therapeutic agents, diagnostic agents (e.g., contrast agents), and any combinations thereof.
  • the active agent present in a silk matrix e.g., a silk microsphere), composition, or the like can include a labile active agent, e.g., an agent that can undergo chemical, physical, or biological change, degradation and/or deactivation after exposure to a specified condition, e.g., high temperatures, high humidity, light exposure, and any combinations thereof.
  • a labile active agent e.g., an agent that can undergo chemical, physical, or biological change, degradation and/or deactivation after exposure to a specified condition, e.g., high temperatures, high humidity, light exposure, and any combinations thereof.
  • the active agent present in the silk matrix can include a temperature-sensitive active agent, e.g., an active agent that will lose at least about 30% or more, of its original activity or bioactivity, upon exposure to a temperature of at least about 10 °C. or above, including at least about 15 °C. or above, at least about room temperature or above, or at least about body temperature (e.g., about 37 °C.) or above.
  • a temperature-sensitive active agent e.g., an active agent that will lose at least about 30% or more, of its original activity or bioactivity, upon exposure to a temperature of at least about 10 °C. or above, including at least about 15 °C. or above, at least about room temperature or above, or at least about body temperature (e.g., about 37 °C.) or above.
  • the active agent can be added into the silk solution, which is then subjected to the methods described herein for preparing a silk matrix (e.g., a silk microsphere), composition, or the like.
  • the active agent can be coated on a surface of the silk matrix (e.g., a silk microsphere), composition, or the like.
  • the active agent can be loaded in a silk matrix (e.g., a silk microsphere), composition, or the like by incubating the silk microsphere in a solution of the active agent for a period of time, during which an amount of the active agent can diffuse into the silk matrix (e.g., a silk microsphere), composition, or the like, and thus distribute within the silk matrix (e.g., a silk microsphere), composition, or the like.
  • the additive is a therapeutic agent.
  • therapeutic agent means a molecule, group of molecules, complex or substance administered to an organism for diagnostic, therapeutic, preventative medical, or veterinary purposes.
  • the term “therapeutic agent” includes a “drug” or a “vaccine.” This term includes externally and internally administered topical, localized and systemic human and animal pharmaceuticals, treatments, remedies, nutraceuticals, cosmeceuticals, biologicals, devices, diagnostics and contraceptives, including preparations useful in clinical and veterinary screening, prevention, prophylaxis, healing, wellness, detection, imaging, diagnosis, therapy, surgery, monitoring, cosmetics, prosthetics, forensics and the like.
  • This term can also be used in reference to agriceutical, workplace, military, industrial and environmental therapeutics or remedies comprising selected molecules or selected nucleic acid sequences capable of recognizing cellular receptors, membrane receptors, hormone receptors, therapeutic receptors, microbes, viruses or selected targets comprising or capable of contacting plants, animals and/or humans.
  • nucleic acids and compounds comprising nucleic acids that produce a therapeutic effect for example deoxyribonucleic acid (DNA), ribonucleic acid (RNA), nucleic acid analogues (e.g., locked nucleic acid (LNA), peptide nucleic acid (PNA), xeno nucleic acid (XNA)), or mixtures or combinations thereof, including, for example, DNA nanoplexes, siRNA, microRNA, shRNA, aptamers, ribozymes, decoy nucleic acids, antisense nucleic acids, RNA activators, and the like.
  • any therapeutic agent can be included in the composition provided herein.
  • therapeutic agent also includes an agent that is capable of providing a local or systemic biological, physiological, or therapeutic effect in the biological system to which it is applied.
  • the therapeutic agent can act to control infection or inflammation, enhance cell growth and tissue regeneration, control tumor growth, act as an analgesic, promote anti-cell attachment, and enhance bone growth, among other functions.
  • suitable therapeutic agents can include anti-viral agents, hormones, antibodies, or therapeutic proteins.
  • Other therapeutic agents include prodrugs, which are agents that are not biologically active when administered but upon administration to a subject are converted to biologically active agents through metabolism or some other mechanism.
  • a silk-based drug delivery composition can contain one therapeutic agent or combinations of two or more therapeutic agents.
  • a therapeutic agent can include a wide variety of different compounds, including chemical compounds and mixtures of chemical compounds, e.g., small organic or inorganic molecules; saccharides; oligosaccharides; polysaccharides; biological macromolecules, e.g., peptides, proteins, and peptide analogs and derivatives; peptidomimetics; antibodies and antigen binding fragments thereof; nucleic acids; nucleic acid analogs and derivatives; an extract made from biological materials such as bacteria, plants, fungi, or animal cells; animal tissues; naturally occurring or synthetic compositions; and any combinations thereof.
  • the therapeutic agent is a small molecule.
  • bioactivity generally refers to the ability of an active agent to interact with a biological target and/or to produce an effect on a biological target.
  • bioactivity can include, without limitation, elicitation of a stimulatory, inhibitory, regulatory, toxic or lethal response in a biological target.
  • the biological target can be a molecule or a cell.
  • a bioactivity can refer to the ability of an active agent to modulate the effect/activity of an enzyme, block a receptor, stimulate a receptor, modulate the expression level of one or more genes, modulate cell proliferation, modulate cell division, modulate cell morphology, or any combination thereof.
  • a bioactivity can refer to the ability of a compound to produce a toxic effect in a cell.
  • exemplary cellular responses include, but are not limited to, lysis, apoptosis, growth inhibition, and growth promotion; production, secretion, and surface expression of a protein or other molecule of interest by the cell; membrane surface molecule activation including receptor activation; transmembrane ion transports; transcriptional regulations; changes in viability of the cell; changes in cell morphology; changes in presence or expression of an intracellular component of the cell; changes in gene expression or transcripts; changes in the activity of an enzyme produced within the cell; and changes in the presence or expression of a ligand and/or receptor (e.g., protein expression and/or binding activity).
  • a ligand and/or receptor e.g., protein expression and/or binding activity
  • Methods for assaying different cellular responses are well known to one of skill in the art, e.g., western blot for determining changes in presence or expression of an endogenous protein of the cell, or microscopy for monitoring the cell morphology in response to the active agent, or FISH and/or qPCR for the detection and quantification of changes in nucleic acids.
  • Bioactivity can be determined in some embodiments, for example, by assaying a cellular response.
  • bioactivity includes, but is not limited to, epitope or antigen binding affinity, the in vivo and/or in vitro stability of the antibody, the immunogenic properties of the antibody, e.g., when administered to a human subject, and/or the ability to neutralize or antagonize the bioactivity of a target molecule in vivo or in vitro.
  • the aforementioned properties or characteristics can be observed or measured using art-recognized techniques including, but not limited to, scintillation proximity assays, ELISA, ORIGEN immunoassay (IGEN), fluorescence quenching, fluorescence ELISA, competitive ELISA, SPR analysis including, but not limited to, SPR analysis using a BIAcore biosensor, in vitro and in vivo neutralization assays (see, for example, International Publication No. WO 2006/062685), receptor binding, and immunohistochemistry with tissue sections from different sources including human, primate, or any other source as needed.
  • the “bioactivity” includes immunogenicity, the definition of which is discussed in detail later.
  • the “bioactivity” includes infectivity, the definition of which is discussed in detail later.
  • the “bioactivity” refers to the ability of a contrast agent when administered to a subject to enhance the contrast of structures or fluids within the subject’s body.
  • the bioactivity of a contrast agent also includes, but is not limited to, its ability to interact with a biological environment and/or influence the response of another molecule under certain conditions.
  • small molecule can refer to compounds that are “natural productlike,” however, the term “small molecule” is not limited to “natural product-like” compounds. Rather, a small molecule is typically characterized in that it contains several carbon — carbon bonds and has a molecular weight of less than 5000 Daltons (5 kDa), preferably less than 3 kDa, still more preferably less than 2 kDa, and most preferably less than 1 kDa. In some cases, it is preferred that a small molecule has a molecular weight equal to or less than 700 Daltons.
  • Exemplary therapeutic agents include, but are not limited to, those found in Harrison’ s Principles of Internal Medicine, 13th Edition, Eds. T.R. Harrison et al. McGraw-Hill N.Y., NY; Physicians’ Desk Reference, 50th Edition, 1997, Oradell New Jersey, Medical Economics Co.; Pharmacological Basis of Therapeutics, 8th Edition, Goodman and Gilman, 1990; United States Pharmacopeia, The National Formulary, ETSP XII NF XVII, 1990, the complete contents of all of which are incorporated herein by reference.
  • Therapeutic agents include the herein disclosed categories and specific examples. It is not intended that the category be limited by the specific examples. Those of ordinary skill in the art will recognize also numerous other compounds that fall within the categories and that are useful according to the present disclosure. Examples include a radiosensitizer, a steroid, a xanthine, a beta- 2-agonist bronchodilator, an anti-inflammatory agent, an analgesic agent, a calcium antagonist, an angiotensin-converting enzyme inhibitors, a beta-blocker, a centrally active alpha- agonist, an alpha - 1 -antagonist, an anticholinergic/antispasmodic agent, a vasopressin analogue, an antiarrhythmic agent, an antiparkinsonian agent, an antiangina/antihypertensive agent, an anticoagulant agent, an antiplatelet agent, a sedative, an anxiolytic agent, a peptidic agent, a biopolymeric agent, an antineoplastic agent
  • the pharmaceutically active agent can be coumarin, albumin, steroids such as betamethasone, dexamethasone, methylprednisolone, prednisolone, prednisone, triamcinolone, budesonide, hydrocortisone, and pharmaceutically acceptable hydrocortisone derivatives; xanthines such as theophylline and doxophylline; beta-2- agonist bronchodilators such as salbutamol, fenterol, clenbuterol, bambuterol, and salmeterol; antiinflammatory agents, including antiasthmatic anti-inflammatory agents, antiarthritis antiinflammatory agents, and non-steroidal anti-inflammatory agents, examples of which include but are not limited to sulfides, mesalamine, budesonide, salazopyrin, diclofenac, pharmaceutically acceptable diclofenac salts, nimesulide, naproxen, acetaminophen, ibuprofen
  • Anti-cancer agents include alkylating agents, platinum agents, antimetabolites, topoisomerase inhibitors, antitumor antibiotics, antimitotic agents, aromatase inhibitors, thymidylate synthase inhibitors, DNA antagonists, farnesyltransferase inhibitors, pump inhibitors, histone acetyltransferase inhibitors, metalloproteinase inhibitors, ribonucleoside reductase inhibitors, TNF alpha agonists/antagonists, endothelin A receptor antagonists, retinoic acid receptor agonists, immunomodulators, hormonal and antihormonal agents, photodynamic agents, and tyrosine kinase inhibitors.
  • Antibiotics include aminoglycosides (e.g., gentamicin, tobramycin, netilmicin, streptomycin, amikacin, neomycin), bacitracin, carbapenems (e.g., imipenem/cilastatin), cephalosporins, colistin, methenamine, monobactams (e.g., aztreonam), penicillins (e.g., penicillin G, penicillin V, methicillin, nafcillin, oxacillin, cioxacillin, dicloxacillin, ampicillin, amoxicillin, carbenicillin, ticarcillin, piperacillin, mezlocillin, azlocillin), polymyxin B, quinolones, and vancomycin; and bacteriostatic agents such as chloramphenicol, clindamycin, macrolides (e.g., erythromycin, azithromycin, clar
  • Enzyme inhibitors are substances which inhibit an enzymatic reaction.
  • enzyme inhibitors include edrophonium chloride, N-methylphysostigmine, neostigmine bromide, physostigmine sulfate, tacrine, 1-hydroxymaleate, iodotubercidin, p-bromotetranisole, 10-(alpha- diethylaminopropionyl)-phenothiazine hydrochloride, calmidazolium chloride, hemicholinium-3,3,5- dinitrocatechol, diacylglycerol kinase inhibitor I, diacylglycerol kinase inhibitor II, 3- phenylpropargylamine, N°-monomethyl-L-arginine acetate, carbidopa, 3 -hydroxybenzylhydrazine, hydralazine, clorgyline, deprenyl, hydroxylamine, iproniazi
  • Antihistamines include pyrilamine, chlorpheniramine, and tetrahydrozoline, among others.
  • Anti-inflammatory agents include corticosteroids, nonsteroidal anti-inflammatory drugs (e.g., aspirin, phenylbutazone, indomethacin, sulindac, tolmetin, ibuprofen, piroxicam, and fenamates), acetaminophen, phenacetin, gold salts, chloroquine, D-Penicillamine, methotrexate colchicine, allopurinol, probenecid, and sulfinpyrazone.
  • nonsteroidal anti-inflammatory drugs e.g., aspirin, phenylbutazone, indomethacin, sulindac, tolmetin, ibuprofen, piroxicam, and fenamates
  • acetaminophen phenacetin
  • gold salts chloroquine
  • Muscle relaxants include mephenesin, methocarbamol, cyclobenzaprine hydrochloride, trihexyphenidyl hydrochloride, levodopa/carbidopa, and biperiden.
  • Anti-spasmodics include atropine, scopolamine, oxyphenonium, and papaverine.
  • Analgesics include aspirin, phenylbutazone, indomethacin, sulindac, tolmetin, ibuprofen, piroxicam, fenamates, acetaminophen, phenacetin, morphine sulfate, codeine sulfate, meperidine, nalorphine, opioids (e.g., codeine sulfate, fentanyl citrate, hydrocodone bitartrate, loperamide, morphine sulfate, noscapine, norcodeine, normorphine, thebaine, nor-binaltorphimine, buprenorphine, chlomaltrexamine, funaltrexamine, nalbuphine, nalorphine, naloxone, naloxonazine, naltrexone, and naltrindole), procaine, lidocaine, tetracaine and dibucaine.
  • Ophthalmic agents include sodium fluorescein, rose bengal, methacholine, adrenaline, cocaine, atropine, alphachymotrypsin, hyaluronidase, betaxolol, pilocarpine, timolol, timolol salts, and combinations thereof.
  • Prostaglandins are art recognized and are a class of naturally occurring chemically related long-chain hydroxy fatty acids that have a variety of biological effects.
  • Anti-depressants are substances capable of preventing or relieving depression.
  • anti-depressants examples include imipramine, amitriptyline, nortriptyline, protriptyline, desipramine, amoxapine, doxepin, maprotiline, tranylcypromine, phenelzine, and isocarboxazid.
  • Trophic factors are factors whose continued presence improves the viability or longevity of a cell trophic factors include, without limitation, platelet-derived growth factor (PDGP), neutrophilactivating protein, monocyte chemoattractant protein, macrophage- inflammatory protein, platelet factor, platelet basic protein, and melanoma growth stimulating activity; epidermal growth factor, transforming growth factor (alpha), fibroblast growth factor, platelet- derived endothelial cell growth factor, insulin-like growth factor, glial derived growth neurotrophic factor, ciliary neurotrophic factor, nerve growth factor, bone growth/cartilage-inducing factor (alpha and beta), bone morphogenetic proteins, interleukins (e.g., interleukin inhibitors or interleukin receptors, including interleukin 1 through interleukin 10), interferons (e.g., interferon alpha, beta and gamma), hematopoietic factors, including erythropoietin,
  • Hormones include estrogens (e.g., estradiol, estrone, estriol, diethylstilbestrol, quinestrol, chlorotrianisene, ethinyl estradiol, mestranol), anti-estrogens (e.g., clomiphene, tamoxifen), progestins (e.g., medroxyprogesterone, norethindrone, hydroxyprogesterone, norgestrel), antiprogestin (mifepristone), androgens (e.g., testosterone cypionate, fluoxymesterone, danazol, testolactone), anti- androgens (e.g., cyproterone acetate, flutamide), thyroid hormones (e.g., triiodothyronne, thyroxine, propylthiouracil, methimazole, and iodixode), and pituitary hormones (e
  • Hormones are commonly employed in hormone replacement therapy and/or for purposes of birth control. Steroid hormones, such as prednisone, are also used as immunosuppressants and anti-inflammatories.
  • the additive is an agent that stimulates tissue formation, and/or healing and regrowth of natural tissues, and any combinations thereof.
  • Agents that increase formation of new tissues and/or stimulates healing or regrowth of native tissue at the site of injection can include, but are not limited to, fibroblast growth factor (FGF), transforming growth factor- beta (TGF-beta, platelet-derived growth factor (PDGF), epidermal growth factors (EGFs), connective tissue activated peptides (CTAPs), osteogenic factors including bone morphogenic proteins, heparin, angiotensin II (A-II) and fragments thereof, insulin-like growth factors, tumor necrosis factors, interleukins, colony stimulating factors, erythropoietin, nerve growth factors, interferons, biologically active analogs, fragments, and derivatives of such growth factors, and any combinations thereof.
  • FGF fibroblast growth factor
  • TGF-beta transforming growth factor- beta
  • PDGF platelet-derived growth factor
  • EGFs epidermal growth factors
  • CTAPs connective tissue activated peptides
  • osteogenic factors including bone morph
  • the silk composition can further comprise at least one additional material for soft tissue augmentation, e.g., dermal filler materials, including, but not limited to, poly(methyl methacrylate) microspheres, hydroxyapatite, poly(L-lactic acid), collagen, elastin, and glycosaminoglycans, hyaluronic acid, commercial dermal filler products such as BOTOX® (from Allergan), DYSPORT®, COSMODERM®, EVOLENCE®, RADIESSE®,RESTYLANE®, JUVEDERM® (from Allergan), SCULPTRA®, PERLANE®, and CAPTIQEIE®, and any combinations thereof.
  • dermal filler materials including, but not limited to, poly(methyl methacrylate) microspheres, hydroxyapatite, poly(L-lactic acid), collagen, elastin, and glycosaminoglycans, hyaluronic acid, commercial dermal filler products such as BOTOX® (from
  • the additive is a wound healing agent.
  • a wound healing agent is a compound or composition that actively promotes wound healing process.
  • the active agents provided herein are immunogens.
  • the immunogen is a vaccine.
  • Most vaccines are sensitive to environmental conditions under which they are stored and/or transported. For example, freezing may increase reactogenicity (e.g., capability of causing an immunological reaction) and/or loss of potency for some vaccines (e.g., HepB, and DTaP/IPV/FQB), or cause hairline cracks in the container, leading to contamination. Further, some vaccines (e.g., BCG, Varicella, and MMR) are sensitive to heat.
  • compositions and methods provided herein also provide for stabilization of vaccines regardless of the cold chain and/or other environmental conditions.
  • the additive is a cell, e.g., a biological cell.
  • Cells useful for incorporation into the composition can come from any source, e.g., mammalian, insect, plant, etc.
  • the cell can be a human, rat or mouse cell.
  • cells to be used with the compositions provided herein can be any types of cells.
  • the cells should be viable when encapsulated within compositions.
  • cells that can be used with the composition include, but are not limited to, mammalian cells (e.g.
  • exemplary cells that can be used with the compositions include platelets, activated platelets, stem cells, totipotent cells, pluripotent cells, and/or embryonic stem cells.
  • exemplary cells that can be encapsulated within compositions include, but are not limited to, primary cells and/or cell lines from any tissue.
  • cardiomyocytes myocytes, hepatocytes, keratinocytes, melanocytes, neurons, astrocytes, embryonic stem cells, adult stem cells, hematopoietic stem cells, hematopoietic cells (e.g. monocytes, neutrophils, macrophages, etc.), ameloblasts, fibroblasts, chondrocytes, osteoblasts, osteoclasts, neurons, sperm cells, egg cells, liver cells, epithelial cells from lung, epithelial cells from gut, epithelial cells from intestine, liver, epithelial cells from skin, etc., and/or hybrids thereof, can be included in the silk/platelet compositions disclosed herein.
  • Cells listed herein represent an exemplary, not comprehensive, list of cells.
  • Cells can be obtained from donors (allogenic) or from recipients (autologous). Cells can be obtained, as a non-limiting example, by biopsy or other surgical means known to those skilled in the art.
  • the cell can be a genetically modified cell.
  • a cell can be genetically modified to express and secrete a desired compound, e.g. a bioactive agent, a growth factor, differentiation factor, cytokines, and the like.
  • a desired compound e.g. a bioactive agent, a growth factor, differentiation factor, cytokines, and the like.
  • Differentiated cells that have been reprogrammed into stem cells can also be used.
  • Example 1 SF and TA Powders
  • Freeze-dried silk fibroin powder and TA powder are ground in a 1 :1 mass ratio. Grinding using a mortar and pestle achieves material homogenization and reduces particle sizes, enhancing dissolution of the powder in water. A ball mill or cryomill may be more effective than manual grinding. This resulting powder can be easily transferred into a syringe, compressed using the plunger, and subsequently deployed in underwater environments. The syringe allows recovery of either fresh or seawater, which can then be mixed with the powder using the plunger. This process enables preparation and delivery of the adhesive within a matter of seconds. Based on weight analysis described herein, the coacervate absorbs approximately its own mass in water during mixing. Therefore, it is more accurate to describe the coacervate composition as 25% silk, 25% tannic acid, and 50% water. An overview of the coacervation process is shown in Fig. 2.
  • Fig. 4a presents the stress-strain curves for the plain coacervate (four measurements) after one hour of application at 20 °C in seawater. These curves were used to calculate the Young’s modulus (E) in the initial linear region (strain ⁇ 10%) of the curve, yielding 120.82 ⁇ 64.56 kPa.
  • Fig. 4b shows the complex modulus (G) in the plateau region (strain ⁇ 10%) for the same material from an amplitude sweep test at 20 °C, with a value of 39.95 ⁇ 37.2 kPa.
  • Figs. 4e-4g illustrate several possible application methods for this adhesive.
  • Fig. 4e demonstrates the potential use of a solid adhesive tablet. In this approach, the tablet is confined within a rigid support (such as a glass coverslip), and frictional heat is applied to locally melt the adhesive, anchoring it to the base.
  • Fig. 4f shows the application of a flexible tag onto a submerged substrate. The coacervate was spread onto a polyurethane tag, which was pre-attached to the exterior of a Ziplock bag using double-sided tape. Filling the bag with hot water (40 °C - 50 °C) keeps the adhesive in a softened, active state, allowing it to bond to a surface upon application of pressure.
  • hot water 40 °C - 50 °C
  • This method enables adhesion to curved or irregular surfaces (e.g., a wrist), and the Ziplock bag can be easily removed as the double-sided tape has low water resistance.
  • the adhesive provides strong immediate adhesion, securing the tag in place even under vigorous mechanical agitation.
  • Fig. 4g presents a device incorporating a USB heating pad embedded within an epoxy resin plate, designed for controlled adhesive applications.
  • the subsequent images show the bottom view of the plate positioned inside a glass container before activation of the USB heater and after cooling. Upon activation, the heater melts the adhesive, which then flows spontaneously onto the bottom of the glass tank. Once cooled, the adhesive solidifies, forming a secure bond without requiring external pressure.
  • a preliminary modification of SF with polydopamine (PDA) results in a longer-lasting adhesion of the coacervates as shown in Fig. 5.
  • the modified silk displayed a gradual reduction in adhesive performance over time, generally remaining below 100 kPa.
  • the DA-modified silk exhibited higher adhesion strength, around 300 kPa, and maintained more consistent performance over three weeks underwater.
  • the control solid coacervate obtained by grinding 350 mg of SF powder and 350 mg of TA powder, was activated by adding the same mass (700 pL) of seawater, mixed, and then directly spread on glass adherents over a 10 x 25 mm area. It was then tested in lap shear measurements.
  • the control coacervate displayed very low values of initial adhesion (6.4 + 2 kPa), which can be increased by pre-heating the coacervate to 60 °C prior to its application (23.4 ⁇ 10.5 kPa).
  • the increased adhesion value after heating is because the coacervate phase consists of a hydrogen-bonded network. Increasing the temperature breaks some of the electrostatic interactions, causing the coacervate to melt.
  • the coacervate reforms the electrostatic bonds, leading to higher cohesion and improved adhesive performance.
  • the shear stress increases to 269.4 ⁇ 149.1 kPa. This increase could also be attributed to the reactive nature of TA, which can undergo covalent cross-linking with free amino groups via a Michael addition reaction.
  • the solid format allows for the inclusion of solid-state reactive additives into the mixture.
  • These additives react with the silk-TA matrix only when the coacervate is activated or applied with water or seawater.
  • One of these additives is calcium chloride (Fig. 7), which acts as a crosslinker for silk fibroin. Adding calcium chloride to the powder in a range between 5% and 20% (w/w%) leads to a change in the adhesive's mechanical behavior. With low calcium content, there is low shear stress (the peak value) and high toughness (area below the curve), while increasing the calcium content reduces toughness and increases the maximum shear stress. This modulation allows for control over the adhesive’s properties, allowing adjustments for either more rigid or plastic behavior as needed.
  • Fig. 9a shows a schematic representation of silk fibroin with abundant P-sheet content.
  • Fig. 9b shows the structure of the polyphenol tannic acid. Introducing iron compounds (FeCh or Fe ⁇ Od to these powders enhances material cohesion through complexation with the tannic acid (TA) (Fig. 9c). Combination of silk fibroin and tannic acid solutions generates coacervates that display immediately underwater adhesion, forming a flexible adhesive (Fig. 9d). Given the high solubility of silk fibroin and tannic acid, the powders can be ground together to create a solid-state material that can also be compressed in a tablet format (Fig. 9g).
  • the silk-based coacervates are applied in a viscous solid form, which can be dispensed from a syringe or similar system.
  • the viscosity is contingent on the composition and temperature of the coacervates. A lower viscosity facilitates the coacervate to fill the irregularities of a rough surface while displacing water. Conversely, higher viscosity is a factor in preventing cohesive failure, ensuring optimal adhesive performance. From our current measurements, we observe that salinity does not impact adhesion performance, and the coacervate in powder form can be activated with either distilled or seawater, yielding consistent results. When heated before application, they attain strengths of up to 500 kPa at 20 °C and remain stable for up to one month.
  • silk and tannic acid can be transformed into a solid-state tablet that transitions into an underwater adhesive upon contact with water or seawater.
  • Silk-based coacervates exhibit melting upon healing and solidification upon cooling. Viscosity at a specific temperature can be regulated by adjusting the silk’s molecular weight or iron content.
  • Fig. 10 shows the coacervate adhesive strengths of up to 150 kPa initially and up to 500 kPa after a few hours underwater, ensuring prolonged adhesion on the order of months.
  • adhesion is between 300 kPa and 400 kPa and is also stable for months.
  • Fig. 11 Iron (III) compounds can be used as crosslinkers as they form complexes with tannic acid’s galloyl moieties. The formation of iron complexes is confirmed by the change of color of the coacervate. Overall, iron (III) compounds improve initial adhesion and durability.
  • iron (III) compounds allows adjustment of the mechanical properties of the adhesive as shown in Fig. 12.
  • the size of iron (III) additives modulates the mechanical properties of the adhesive in underwater environments by changing the behavior of the adhesive from liquid like pressure sensitive adhesive to elastic solids.
  • Iron (III) compounds can be used to finely tune the mechanical behavior of the adhesive by controlling particle size.
  • SF-TA coacervates are hydrogen bonded networks, their viscosity is affected by temperature (Fig. 13a).
  • a probe tack test is depicted in Fig. 13B. Below 10 °C, the SF-TA coacervates are rigid and do not display adhesive behavior, but the SF-TA coacervates melt and are sticky if heated to 15 °C to 30 °C. Above this temperature the SF-TA coacervates behave more like a liquid, reducing their adhesion performance. To extend the temperature range of successful adhesion, iron compounds were incorporated into the coacervates to influence their glass transition temperature, enabling them to exhibit adhesion at higher temperatures.
  • Fig. 14c shows the adhesion of iron oxide coacervate underwater under tensile stress.
  • Fig. 15a-d compares 10% FeCh coacervate to plain coacervate.
  • the plain coacervate melts at a lower temperature and overall exhibits lower adhesion at all temperatures.
  • the temperature dependence of adhesion can be tailored. At low temperature, the 10% FeCI-, coacervate is too rigid and cannot interact with the target surface which results in adhesive failure as shown in Fig. 16a, Fig. 16b, and Fig. 16c.
  • Fig. 16c shows highest adhesion for 0.1 % FeCh at 24 °C while 10% FeCh is highest at 44 °C.
  • Fig 16d shows performance of the adhesives immediately, 1 day after application, and 1 week after application in seawater.
  • Fig. 17 shows (Fig. 17a) and quantifies (Fig. 17b) adhesion on aluminum, glass, polycarbonate, wood, PLA, polystyrene, and Teflon.
  • Fig. 18 shows an overview of an adhesive tablet form of coacervates made of silk fibroin powder, iron (III) compound powder, and tannic acid powder. Briefly, silk fibroin powder, an iron (III) compound powder, and tannic acid powder are mixed and ground together to form a solid-state coacervate powder. The solid-state coacervate powder is then compressed into dry tablets, which activate upon contact with water or seawater to form an underwater viscous adhesive, proving the versatility of this material.
  • Fig. 19 summarizes the experimental setup and results of a constant buoyant stress study.
  • the GPS holder design shown in Fig. 19a, fits the SPOT-253 tag by Wildlife Computers®.
  • the versatility of the coacervate adhesive allows for free selection of the material to be used in the GPS adapter.
  • a silicone GPS holder prototype stuck to a glass wall with the coacervate adhesive under constant water flow of 5.3 m/s is shown in Fig. 19b.
  • a mold was created and cast in flexible material.
  • flow testing was conducted under a constant water stream.
  • the adapter material was tested. Temperature and longevity were characterized.
  • Fig. 19c shows various adhesives used in the experiment.
  • Fig. 19d shows the time to detach under buoyant stress of the adhesives tested.

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  • Adhesives Or Adhesive Processes (AREA)

Abstract

L'invention divulgue une composition à l'état solide comprenant une paire de matériaux formant un coacervat constituée de fibroïne de soie et d'un matériau complémentaire à la soie et des procédés de fabrication et d'utilisation de celle-ci. Une composition adhésive à base de coacervat et ses procédés de fabrication et d'utilisation sont divulgués. La composition comprend un coacervat formé par mélange d'une solution de fibroïne de soie lyophilisée et d'acide tannique. L'acide tannique est présent en une quantité suffisante pour initier la complexation et/ou la réticulation de la composition adhésive. L'adhésif présente de nombreuses applications utiles, mais une application particulièrement intéressante devrait impliquer une application d'adhésif directement sur la peau ou la surface extérieure d'animaux marins, tels que des requins.
PCT/US2025/027523 2024-05-02 2025-05-02 Adhésifs de coacervat à l'état solide et leurs procédés de fabrication et d'utilisation Pending WO2025231379A1 (fr)

Applications Claiming Priority (2)

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US202463641806P 2024-05-02 2024-05-02
US63/641,806 2024-05-02

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WO2025231379A1 true WO2025231379A1 (fr) 2025-11-06

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Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO2024006607A2 (fr) * 2022-06-03 2024-01-04 Trustees Of Tufts College Adhésifs de marquage d'animaux sous-marins et leurs procédés de fabrication et d'utilisation
US20240082405A1 (en) * 2013-03-15 2024-03-14 Trustees Of Tufts College Low Molecular Weight Silk Compositions and Stabilizing Silk Compositions

Patent Citations (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US20240082405A1 (en) * 2013-03-15 2024-03-14 Trustees Of Tufts College Low Molecular Weight Silk Compositions and Stabilizing Silk Compositions
WO2024006607A2 (fr) * 2022-06-03 2024-01-04 Trustees Of Tufts College Adhésifs de marquage d'animaux sous-marins et leurs procédés de fabrication et d'utilisation

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