NL2029961B1

NL2029961B1 - Dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel and preparation method thereof

Info

Publication number: NL2029961B1
Application number: NL2029961A
Authority: NL
Inventors: Li Xun; Ning Like; You Chaoqun; Zhang Yu; Li Dan; Wang Fei
Original assignee: Univ Nanjing Forestry
Priority date: 2021-04-30
Filing date: 2021-11-30
Publication date: 2023-10-20
Also published as: CN113197843A; NL2029961A

Abstract

Disclosed are a dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel and a preparation method thereof, belonging to the field of biological materials. The method includes: mixing dopamine hydrochloride, water and sodium hydroxide to carry out a polymerization reaction, then mixing the resulting system with carboxycellulose nanocrystals for a condensation reaction, and mixing the obtained dopamine-coated cellulose nanocrystals with surfactants, water, drugs and agarose to obtain a dopaminecoated cellulose nanocrystals-agarose drug-loaded hydrogel. The present disclosure uses dopamine to coat the cellulose nanocrystals and then loads the drugs, which can improve the adhesion of the hydrogel to the drug, improve the drug-loading stability and the drugloading rate of the drug-loaded hydrogel, thereby improving the anti-tumor activity. The results of the examples show that the dopamine-coated cellulose nanocrystal-agarose hydrogels provided by the present disclosure have a drug-loading rate of 22.4%, high drug stability, and excellent anti-tumor activity to liver cancer HepG2 cells and human breast cancer MCF-7 cells.

Description

DOPAMINE-COATED CELLULOSE NANOCRYSTAL-AGAROSE DRUG-

LOADED HYDROGEL AND PREPARATION METHOD THEREOF

TECHNICAL FIELD

[01] The present disclosure relates to the technical field of biological materials, in particular to a dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel and a preparation method thereof.

BACKGROUND ART

[02] Hydrogel is a sponge-like material composed of a three-dimensional network of hydrophilic polymers, which can absorb and retain a large amount of water, and is a good material for drug delivery systems. Hydrogel has advantages in improving the retention time of the drug in patient's body, reducing the dosage and administration frequency, reducing the toxic effect of the drug, and improving the compliance of patients by directly loading drugs or by incorporating drug-loaded microparticles, which provides a good platform for the drug delivery system. Generally, hydrogels are classified into two categories according to their origins: biopolymer-based hydrogels or synthetic hydrogels. Agarose is a natural polysaccharide, which has attracted wide attention due to its good biocompatibility and biodegradability.

[03] Cellulose nanocrystal is a kind of cellulose-derived polysaccharide with nano- scale size, which is composed of cellulose. It is one of the most abundant and renewable natural resources, and can be combined with biopolymers such as agarose as a scaffold material for regenerative medicine or as a carrier for drug release, which has been widely used in the field of biomedicine in recent years. At present, cellulose nanocrystals and biopolymers are generally directly prepared into drug carrier hydrogels, and then the drugs are loaded by surface adsorption or electrostatic interaction. However, this method is easily affected by the environment, which reduces its drug-loading stability. At the same time, the drug-loading rate is also small, making its application restricted.

[04] Therefore, how to improve the drug-loading stability and drug-loading rate capacity of the cellulose nanocrystal-biopolymer drug-loaded hydrogel has become a problem in the prior art.

SUMMARY

[05] The purpose of the present disclosure is to provide a dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel and a preparation method thereof. The dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel provided by the present disclosure has excellent drug-loading stability and high drug-loading rate, which can realize the loading, targeted release and sustained release of anti-tumor drugs, and has excellent anti-tumor activity.

[06] In order to achieve the above purpose of the disclosure, the present disclosure provides the following technical schemes:

[07] The present disclosure provides a preparation method of a dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel, including the following steps:

[08] (1) Mixing dopamine hydrochloride, water and sodium hydroxide to carry out a polymerization reaction to obtain a polydopamine solution;

[09] (2) Mixing the polydopamine solution obtained in step (1) with a carboxycellulose nanocrystal, and performing a condensation reaction to obtain a dopamine-coated cellulose nanocrystal;

[10] (3) Mixing the dopamine-coated cellulose nanocrystal obtained in step (2) with a surfactant, water, a drug and agarose, heating and then cooling to obtain the dopamine- coated cellulose nanocrystal-agarose drug-loaded hydrogel.

[11] Preferably, the mass ratio of dopamine hydrochloride and sodium hydroxide in the step (1) is (4-5): 1.

[12] Preferably, the mass ratio of the carboxycellulose nanocrystal in the step (2) to dopamine hydrochloride in the step (1) is (1-3): 1.

[13] Preferably, the surfactant in the step (3) includes one of hexadecylamine, octadecylamine and cetyltrimethylammonium bromide.

[14] Preferably, the mass ratio of the dopamine-coated cellulose nanocrystal to the surfactant in the step (3) is 1: (2-4).

[15] Preferably, the drug in the step (3) includes paclitaxel or adriamycin.

[16] Preferably, the mass ratio of the dopamine-coated cellulose nanocrystal to the drug in the step (3) 1s 1: (1-6).

[17] Preferably, the mass ratio of the dopamine-coated cellulose nanocrystal to the agarose in the step (3) is 1: (3-6).

[18] Preferably, the ratio of the mass of dopamine-coated cellulose nanocrystal to the volume of water in the step (3) is Img: (0.1-0.5) mL.

[19] The present disclosure also provides a dopamine-coated cellulose nanocrystal- agarose drug-loaded hydrogel prepared by the preparation method described in the above technical schemes.

[20] The present disclosure also provides a method for preparing the dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel, comprising the following steps: mixing dopamine hydrochloride, water and sodium hydroxide to carry out a polymerization reaction to obtain a polydopamine solution, mixing the obtained polydopamine solution with a carboxycellulose nanocrystal, and performing a condensation reaction to obtain a dopamine-coated cellulose nanocrystal; mixing the dopamine-coated cellulose nanocrystal with a surfactant, water, a drug and agarose, heating and then cooling to obtain the dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel. The present disclosure uses dopamine to coat the cellulose nanocrystals and then loads drugs, which can improve the adhesion and absorption efficiency of the hydrogel to the drug, and improve the stability and drug-loading rate of the drug-loaded hydrogel, thereby improving the anti-tumor activity. The results of the examples show that the dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel provided by the present disclosure has a drug-loading rate of 22.4%, high drug stability, and significant sustained release ability, which has excellent anti-tumor activity on liver cancer HepG2 cells and human breast cancer MCF-7 cells.

BRIEF DESCRIPTION OF THE DRAWINGS

[21] FIG.1 is a TEM image of the dopamine-coated cellulose nanocrystal-agarose drug- loaded hydrogel prepared in Example 1 of the present disclosure after freeze-drying;

[22] FIG.2 is an in vitro stability diagram of the dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel prepared in Example 1 of the present disclosure after freeze-drying.

[23] FIG. 3 is a diagram of cell adhesion of products prepared in Example 1,

Comparative Example 1 and Comparative Example 2 of the present disclosure;

[24] FIG. 4 is a diagram of anti-tumor activity of the products prepared in Example 1,

Comparative Example 1 and Comparative Example 2 of the present disclosure after freeze-drying.

DETAILED DESCRIPTION OF THE EMBODIMENTS

[25] The present disclosure provides a method of preparing the dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel, including the following steps:

[26] (1) Mixing dopamine hydrochloride, water and sodium hydroxide to carry out a polymerization reaction to obtain a polydopamine solution;

[27] (2) Mixing the polydopamine solution obtained in step (1) with a carboxycellulose nanocrystal, and performing a condensation reaction to obtain a dopamine-coated cellulose nanocrystal;

[28] (3) Mixing the dopamine-coated cellulose nanocrystal obtained in step (2) with a surfactant, water, a drug and agarose, heating and then cooling to obtain the dopamine- coated cellulose nanocrystal-agarose drug-loaded hydrogel.

[29] Unless otherwise specified, the present disclosure does not specifically limit the source of each component, and it is sufficient to use commercially available products or products prepared by conventional preparation methods well known to those skilled in the art.

[30] In the present disclosure, dopamine hydrochloride, water and sodium hydroxide are mixed to carry out a polymerization reaction to obtain a polydopamine solution.

[31] In the present disclosure, the water is preferably deionized water. In the present disclosure, the water is used to dissolve dopamine hydrochloride. In the present disclosure, the ratio of the mass of dopamine hydrochloride to the volume of water is preferably 1 mg: (0.1-0.4) mL, and more preferably 1 mg: (0.2-0.3) mL. The present disclosure limits the ratio of the mass of dopamine hydrochloride to the volume of water 5 within the above range, which can make the dopamine hydrochloride more fully dissolved and facilitate the progress of the polymerization reaction.

[32] In the present disclosure, the mass ratio of the dopamine hydrochloride to sodium hydroxide is preferably (4-5):1, more preferably (4.2-4.8):1, and most preferably (4.4- 4.6):1. In the present disclosure, the sodium hydroxide is used to provide a strong alkaline environment and neutralize the hydrochloric acid in the dopamine hydrochloride. The present disclosure limits the mass ratio of dopamine hydrochloride to sodium hydroxide within the above range, which can fully neutralize the hydrochloric acid in dopamine hydrochloride, increase the content of dopamine, and further improve the drug-loading rate and drug-loading stability of the product.

[33] In the present disclosure, the mixing operation of dopamine hydrochloride, water and sodium hydroxide is not particularly limited, and the technical scheme of mixing materials well known to those skilled in the art may be used. In the present disclosure, the mixing of dopamine hydrochloride, water and sodium hydroxide is preferably as follows: mixing sodium hydroxide and part of water to obtain a Imol/L sodium hydroxide solution, then mixing dopamine hydrochloride and remaining water, and finally adding the sodium hydroxide solution.

[34] In the present disclosure, the temperature of the polymerization reaction is preferably 20-30°C, more preferably 25°C, the time of the polymerization reaction is preferably 1-2 h, more preferably 1.5 h. In the present disclosure, the polymerization reaction is preferably carried out under air conditions.

[35] In the present disclosure, the polymerization reaction is preferably carried out under stirring conditions; the stirring is preferably mechanical stirring. In the present disclosure, the polymerization reaction is preferably carried out under light-shielding conditions, and the light-shielding can avoid the occurrence of side reactions.

[36] The present disclosure limits the temperature and time of the polymerization reaction within the above range, which can make the reaction proceed fully and further improve the drug-loading rate and drug-loading stability of the product. In the present disclosure, during the polymerization reaction process, sodium hydroxide is used to neutralize dopamine hydrochloride to obtain dopamine, and dopamine is polymerized to form a polydopamine solution.

[37] After the polydopamine solution is obtained, the polydopamine solution and the carboxycellulose nanocrystals are mixed to perform a condensation reaction to obtain dopamine-coated cellulose nanocrystals.

[38] The present disclosure does not specifically limit the source of the carboxycellulose nanocrystals, and it can be prepared by a preparation method well known to those skilled in the art. In the present disclosure, the method for preparing the carboxycellulose nanocrystals is preferably as follows: adding 500 mg of cellulose nanocrystals and 50 mg of succinic anhydride to 20 mL of dimethyl sulfoxide, adding 2 mL of N-methylmorpholine as a catalyst, conducting continuous stirring at 60°C for 12 h, then adding 10 mL of ice water, stirring evenly and then centrifuging, washing the precipitate three times with deionized water and then conducting vacuum freeze-drying for 24 h to obtain the carboxycellulose nanocrystals. The present disclosure adopts the above preparation method to enable more carboxyl groups in the carboxycellulose nanocrystals, thereby increasing the content of dopamine in the product, and further improving the drug-loading rate and drug-loading stability of the product.

[39] In the present disclosure, the mass ratio of the carboxycellulose nanocrystals and dopamine hydrochloride is preferably (1-3):1, more preferably (1.5-2.5):1, and most preferably 2:1. The present disclosure limits the mass ratio of carboxycellulose nanocrystals and dopamine hydrochloride to the above range, which can increase the content of dopamine in the product, and further improve the drug-loading rate and drug- loading stability of the product.

[40] In the present disclosure, the mixing operation of the polydopamine solution and carboxycellulose nanocrystals is not particularly limited, and the technical scheme of mixing materials well known to those skilled in the art can be used.

[41] In the present disclosure, the time of the condensation reaction is preferably 1-3 h, more preferably 1.5-2 h; the temperature of the condensation reaction is preferably 20- 30°C, and more preferably 25°C. In the present disclosure, the condensation reaction is preferably carried out under stirring conditions; the stirring is preferably mechanical stirring. The present disclosure limits the temperature and time of the condensation reaction within the above range, which can enable the condensation reaction to proceed fully, increase the content of dopamine in the product, and further improve the drug- loading stability and drug-loading rate of the product. In the present disclosure, the carboxyl groups of the carboxycellulose nanocrystals react with the amino groups in the polydopamine solution during the condensation reaction, so that dopamine is loaded on the carboxycellulose nanocrystals.

[42] In the present disclosure, after the completion of condensation reaction, the condensation reaction product is preferably subjected to post-treatment to obtain dopamine-coated cellulose nanocrystals.

[43] In the present disclosure, the post-treatment preferably includes separation, washing and drying in sequence. In the present disclosure, the separation is preferably centrifugal separation; the washing is preferably washing with deionized water, and the number of washings is preferably 3 times; the drying is preferably freeze-drying; the drying time is preferably 20-30h, and more preferably 24-26h.

[44] After obtaining the dopamine-coated cellulose nanocrystals, the dopamine-coated cellulose nanocrystals are mixed with surfactants, water, drugs and agarose, the resulting mixture was heated and then cooled to obtain dopamine-coated cellulose nanocrystals - agarose drug-loaded hydrogels.

[45] In the present disclosure, the surfactant preferably includes one of hexadecylamine, octadecylamine and cetyltrimethylammonium bromide, and more preferably hexadecylamine. In the present disclosure, the mass ratio of the dopamine- coated cellulose nanocrystals to the surfactant is preferably 1:(2-4), more preferably 1:(2.5-3.5), and most preferably 1:3. The present disclosure limits the mass ratio of the dopamine-coated cellulose nanocrystals to the surfactant within the above range, which can make the dopamine-coated cellulose nanocrystals form a network structure with agarose more uniformly, and at the same time make the drug adhere to the drug-loaded hydrogel more uniformly to further improve the drug-loading stability and drug-loading rate of the product.

[46] In the present disclosure, the water is preferably deionized water. In the present disclosure, the ratio of the mass of dopamine-coated cellulose nanocrystals to the volume of water is preferably 1 mg: (0.1-0.5) mL, more preferably 1 mg: (0.2-0.4) mL, and most preferably 1 mg: 0.3mL. The present disclosure limits the ratio of the mass of dopamine- coated cellulose nanocrystals to the volume of water within the above range, so that the dopamine-coated cellulose nanocrystals can be more fully dispersed.

[47] In the present disclosure, the drug preferably includes paclitaxel or adriamycin, and more preferably paclitaxel. In the present disclosure, the mass ratio of the dopamine- coated cellulose nanocrystals to the drug is preferably 1:(1-6), more preferably 1:(2-5), and most preferably 1:(3-4). The present disclosure limits the mass ratio of dopamine- coated cellulose nanocrystals to the drug within the above range, which can increase the drug-loading rate of the product and further improve the anti-tumor activity.

[48] In the present disclosure, the mass ratio of the dopamine-coated cellulose nanocrystals to agarose is preferably 1:(3-6), and more preferably 1:(4-5). The present disclosure limits the mass ratio of dopamine-coated cellulose nanocrystals to agarose within the above range, which can make the hydrogel have a suitable porous network structure and further increase the drug-loading rate.

[49] In the present disclosure, the mixing operation of the dopamine-coated cellulose nanocrystals with surfactants, water, drugs and agarose is not particularly limited, and a technical scheme for mixing materials well known to those skilled in the art may be used. In the present disclosure, the mixing of the dopamine-coated cellulose nanocrystals with surfactants, water, drugs and agarose is preferably as follows: dispersing the dopamine-coated cellulose nanocrystals and hexadecylamine in water, then adding drugs, and finally adding agarose. In the present disclosure, the mixing of the dopamine-

coated cellulose nanocrystals with surfactants, water, drugs and agarose is preferably carried out under ultrasonic conditions, and the ultrasonic power is preferably 80-120W, and more preferably 100W; the ultrasonic time is preferably 5-10min, and more preferably 7-9min; the ultrasonic temperature is preferably 20-30°C, and more preferably 25°C. In the present disclosure, in the ultrasonic process, the ultrasonic probe is preferably placed below the liquid surface.

[50] In the present disclosure, the heating temperature is preferably 80-100°C, and more preferably 90°C; the heating time is preferably 1-10 min, and more preferably 5 min. In the present disclosure, the heating is preferably performed under water bath conditions. In the present disclosure, the heating temperature and time are limited within the above ranges, which can make the agarose fully dissolved, and then form a porous network structure with the dopamine-coated cellulose nanocrystals. [S1] In the present disclosure, the cooling is preferably natural cooling, and the end of the cooling is preferably room temperature.

[52] The present disclosure uses dopamine to coat the cellulose nanocrystals and then loads the drugs, which can improve the adhesion and absorption efficiency of the hydrogel to the drugs, control the dosage of each component, reaction temperature and time and other process parameters, and improve the drug-loading stability and drug- loading rate of the hydrogel, thereby improving the anti-tumor activity.

[53] The present disclosure also provides the dopamine-coated cellulose nanocrystal- agarose drug-loaded hydrogel prepared by the preparation method described in the above technical scheme.

[54] The dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel provided by the present disclosure has excellent drug-loading stability and high drug- loading rate, which can realize the loading, targeted release and sustained release of anti- tumor drugs, and has excellent anti-tumor activity.

[55] The technical schemes of the present disclosure will be clearly and completely described below in conjunction with the embodiments of the present disclosure.

Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all the embodiments. Based on the embodiments of the present disclosure, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of the present disclosure.

[56] Example 1

[57] (1) 500 mg of cellulose nanocrystals and 50 mg of succinic anhydride were added to 20 mL of dimethyl sulfoxide, 2 mL of N-methylmorpholine was added as a catalyst, the resulting mixture was stirred continuously at 60°C for 12 h, then 10 mL of ice water was added, stirred uniformly, then the mixture was subjected to centrifugal separation, the resulting precipitate was washed three times with deionized water and then subjected to vacuum freeze-drying for 24 h to obtain the carboxycellulose nanocrystals;

[58] (2) 75mg of dopamine hydrochloride was added to 20mL of deionized water, and 400uL of Imol/L sodium hydroxide solution (the mass ratio of dopamine hydrochloride to sodium hydroxide of 4.7:1; the ratio of the mass of dopamine hydrochloride to the volume of deionized water of Img: 0.27mL) was added, the resulting system was protected from light, stirred in the air at 25°C for 1.5h to obtain a polydopamine solution;

[59] (3) 150 mg of the carboxycellulose nanocrystal prepared in step (1) (the mass ratio of carboxycellulose nanocrystal to dopamine hydrochloride of 2:1) was added into the polydopamine solution prepared in step (2), stirred at 25°C for 2 h, then subjected to centrifugal separation, the resulting precipitate was washed three times with deionized water and then subjected to vacuum freeze-drying for 24 h to obtain the dopamine-coated cellulose nanocrystals;

[60] (4) 30 mg of the dopamine-coated cellulose nanocrystals prepared in step (3) and 90 mg of hexadecylamine were dispersed in 6 mL of deionized water, the ultrasonic probe was placed below the liquid surface, the resulting system was subjected to ultrasonic treatment at 25°C for 5 min with a power of 100W, 120 mg of paclitaxel was added, the ultrasonic treatment was continued for 2 min, 120mg of agarose (the mass ratio of dopamine-coated cellulose nanocrystals to hexadecylamine of 1:3, the ratio of the mass of dopamine-coated cellulose nanocrystals to the volume of deionized water of

Img: 0.2mL, the mass ratio of dopamine-coated cellulose nanocrystals to paclitaxel of

1:4, and the mass ratio of dopamine-coated cellulose nanocrystals to agarose of 1:4) was added, the resulting mixture was put in a water bath at 90°C for 5 min to mix evenly, cooled to room temperature and shaped to obtain a dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel.

[61] Example 2

[62] (1) 500 mg of cellulose nanocrystals and 50 mg of succinic anhydride were added to 20 mL of dimethyl sulfoxide, 2 mL of N-methylmorpholine was added as a catalyst, the resulting mixture was stirred continuously at 60°C for 12 h, then 10 mL of ice water was added, stirred uniformly, then the mixture was subjected to centrifugal separation, the resulting precipitate was washed three times with deionized water and then subjected to vacuum freeze-drying for 24 h to obtain the carboxycellulose nanocrystals;

[63] (2) 100mg of dopamine hydrochloride was added to 20mL of deionized water, and 520uL of 1mol/L sodium hydroxide solution (the mass ratio of dopamine hydrochloride to sodium hydroxide of 4.8:1; the ratio of the mass of dopamine hydrochloride to the volume of deionized water of Img: 0.2mL) was added, the resulting system was protected from light, stirred in the air at 25°C for 1.5h to obtain a polydopamine solution;

[64] (3) 150 mg of the carboxycellulose nanocrystal prepared in step (1) (the mass ratio of carboxycellulose nanocrystal to dopamine hydrochloride of 1.5:1) was added into the polydopamine solution prepared in step (2), stirred at 25°C for 2 h, then subjected to centrifugal separation, the resulting precipitate was washed three times with deionized water and then subjected to vacuum freeze-drying for 24 h to obtain the dopamine-coated cellulose nanocrystals;

[65] (4) 15 mg of the dopamine-coated cellulose nanocrystals prepared in step (3) and 45 mg of hexadecylamine were dispersed in 3 mL of deionized water, the ultrasonic probe was placed below the liquid surface, the resulting system was subjected to ultrasonic treatment at 25°C for 5 min with a power of 100W, 60 mg of paclitaxel was added, the ultrasonic treatment was continued for 2 min, 60mg of agarose (the mass ratio of dopamine-coated cellulose nanocrystals to hexadecylamine of 1:3, the ratio of the mass of dopamine-coated cellulose nanocrystals to the volume of deionized water of

Img: 0.2mL, the mass ratio of dopamine-coated cellulose nanocrystals to paclitaxel of 1:4, and the mass ratio of dopamine-coated cellulose nanocrystals to agarose of 1:4) was added, the resulting mixture was put in a water bath at 90°C for 5 min to mix evenly, cooled to room temperature and shaped to obtain a dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel.

[66] Example 3

[67] (1) 500 mg of cellulose nanocrystals and 50 mg of succinic anhydride were added to 20 mL of dimethyl sulfoxide, 2 mL of N-methylmorpholine was added as a catalyst, the resulting mixture was stirred continuously at 60°C for 12 h, then 10 mL of ice water was added, stirred uniformly, then the mixture was subjected to centrifugal separation, the resulting precipitate was washed three times with deionized water and then subjected to vacuum freeze-drying for 24 h to obtain the carboxycellulose nanocrystals;

[68] (2) 50mg of dopamine hydrochloride was added to 15mL of deionized water, and 260uL of 1mol/L sodium hydroxide solution (the mass ratio of dopamine hydrochloride to sodium hydroxide of 4.8:1; the ratio of the mass of dopamine hydrochloride to the volume of deionized water of Img: 0.3mL) was added, the resulting system was protected from light, stirred in the air at 25°C for 1.5h to obtain a polydopamine solution;

[69] (3) 125 mg of the carboxycellulose nanocrystal prepared in step (1) (the mass ratio of carboxycellulose nanocrystal to dopamine hydrochloride of 2.5:1) was added into the polydopamine solution prepared in step (2), stirred at 25°C for 2 h, then subjected to centrifugal separation, the resulting precipitate was washed three times with deionized water and then subjected to vacuum freeze-drying for 24 h to obtain the dopamine-coated cellulose nanocrystals;

[70] (4) 30 mg of the dopamine-coated cellulose nanocrystals prepared in step (3) and 90 mg of hexadecylamine were dispersed in 6 mL of deionized water, the ultrasonic probe was placed below the liquid surface, the resulting system was subjected to ultrasonic treatment at 25°C for 5 min with a power of 100W, 120 mg of paclitaxel was added, the ultrasonic treatment was continued for 2 min, 120mg of agarose (the mass ratio of dopamine-coated cellulose nanocrystals to hexadecylamine of 1:3, the ratio of the mass of dopamine-coated cellulose nanocrystals to the volume of deionized water of

[71] Comparative Example 1

[72] (1) 500 mg of cellulose nanocrystals and 50 mg of succinic anhydride were added to 20 mL of dimethyl sulfoxide, 2 mL of N-methylmorpholine was added as a catalyst, the resulting mixture was stirred continuously at 60°C for 12 h, then 10 mL of ice water was added, stirred uniformly, then the mixture was subjected to centrifugal separation, the resulting precipitate was washed three times with deionized water and then subjected to vacuum freeze-drying for 24 h to obtain the carboxycellulose nanocrystals;

[73] (2) 30 mg of the carboxycellulose nanocrystals prepared in step (1) and 90 mg of hexadecylamine were dispersed in 6 mL of deionized water, the ultrasonic probe was placed below the liquid surface, the resulting system was subjected to ultrasonic treatment at 25°C for 5 min with a power of 100W, 120 mg of paclitaxel was added, the ultrasonic treatment was continued for 2 min, 120mg of agarose was added, the resulting mixture was put in a water bath at 90°C for 5 min to mix evenly, cooled to room temperature and shaped to obtain a cellulose nanocrystal-agarose drug-loaded hydrogel.

[74] Comparative Example 2

[75] (1) 500 mg of cellulose nanocrystals and 50 mg of succinic anhydride were added to 20 mL of dimethyl sulfoxide, 2 mL of N-methylmorpholine was added as a catalyst, the resulting mixture was stirred continuously at 60°C for 12 h, then 10 mL of ice water was added, stirred uniformly, then the mixture was subjected to centrifugal separation, the resulting precipitate was washed three times with deionized water and then subjected to vacuum freeze-drying for 24 h to obtain the carboxycellulose nanocrystals;

[76] (2) 75mg of dopamine hydrochloride was added to 20mL of deionized water, 400uL of 1mol/L sodium hydroxide solution was added, the resulting system was protected from light, stirred in the air at 25°C for 1.5h to obtain a polydopamine solution;

[77] (3) 150 mg of the carboxycellulose nanocrystals prepared in step (1) was added into the polydopamine solution prepared in step (2), stirred at 25°C for 2 h, then subjected to centrifugal separation, the resulting precipitate was washed three times with deionized water and then subjected to vacuum freeze-drying for 24 h to obtain the dopamine-coated cellulose nanocrystals;

[78] (4) 30 mg of the dopamine-coated cellulose nanocrystals prepared in step (3) and 90 mg of hexadecylamine were dispersed in 6 mL of deionized water, the ultrasonic probe was placed below the liquid surface, the resulting system was subjected to ultrasonic treatment at 25°C for 5 min with a power of 100W, 120mg of agarose was added, the resulting mixture was put in a water bath at 90°C for 5 min to mix evenly, cooled to room temperature and shaped to obtain a dopamine-coated cellulose nanocrystal-agarose hydrogel.

[79] The dopamine-coated cellulose nanocrystal-agarose hydrogel prepared in

Example 1 was freeze-dried for 12 h and then characterized by transmission electron microscopy. The result is shown in FIG. 1. It can be seen from FIG. 1 that the drug- loaded hydrogel prepared by the present disclosure has a porous network structure.

[80] The in vitro stability of the dopamine-coated cellulose nanocrystal-agarose drug- loaded hydrogel prepared in Example 1 was tested as follows: phosphate buffer solutions with pH values of 5.5, 6.8 and 7.4 were used to simulate the physiological environment in vivo, and 5 mg of the dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogel prepared in Example 1 after freeze-drying for 12 h was weighed and added to 3 mL of 0.2 mol/L phosphate buffer solutions (pH values of 5.5, 6.8, and 7.4, respectively), the resulting mixture was loaded into a dialysis bag (1000D), placed into a beaker containing 100 mL of phosphate buffer solution after the seal of the dialysis bag, and dialyzed at 37°C for 7 days. During this period, an ultraviolet spectrophotometer was used to monitor the changes in the ultraviolet absorbance of the dialysate at 227 nm. The cumulative release concentration of paclitaxel is obtained from the UV absorption-concentration standard curve of paclitaxel, and the cumulative release rate is the ratio of the cumulative release concentration of paclitaxel to the theoretical final concentration of paclitaxel completely released, and the result is shown in FIG 2.

It can be seen from FIG. 2 that in a phosphate buffer solution (physiological environment) with a pH of 7.4, the maximum cumulative release rate of paclitaxel is about 11%, and the drug release comes from diffusion; while in a phosphate buffer solution with a pH of 5.5 (the pH value of the tissue fluid around the cancer cells), the cumulative release rate of the drug is as high as 86%, and the drug release comes from the diffusion and the degradation of the carrier. The drug-loaded hydrogel prepared by the present disclosure has the performance of sustained drug release under physiological conditions and accelerates the release in the lesion part. Within 7 days of dialysis, the absorption of the dialysate is stable under the condition of pH 7.4, and the absorbance of the dialysate continues to increase under the condition of pH 5.5, indicating that the drug-loaded hydrogel prepared by the present disclosure has high drug-loading stability and remarkable sustained release performance.

[81] The drug-loading rates of the products prepared in Example 1, Example 2,

Example 3 and Comparative Example 1 were tested: 8mg of the products prepared in

Examples 1-3 and Comparative Example 1 after freeze-drying were dispersed in 8 mL of water and centrifuged at 8000 rpm/min for 5 min, the supernatant was taken and the absorbance at 227nm was measured with an ultraviolet spectrophotometer, and the drug- loading rate of the product was calculated according to formula I:

Xpry

Drug-loading ratio DL3 = ——— = 100% 52] total mass of the sample formula L

[83] Where Xprx is the mass of free paclitaxel in the drug-loaded hydrogel calculated by substituting the absorbance value into the standard curve. The results are listed in

Table 1. It can be seen from Table 1 that the addition of dopamine significantly improves the drug-loading rate of the product.

[84] Table 1 Drug-loading rate of the products prepared in Example 1-3 and

Comparative Example 1 er [Fo [ese

[86] The cell adhesion performance of the products prepared in Example 1,

Comparative Example 1 and Comparative Example 2 were tested: 200 uL of the products prepared in Example 1, Comparative Example 1 and Comparative Example 2 were heated and dissolved at 90°C, then dropped into a 96-well plate, and cooled to form, before contacting with cells, the product was swollen in complete medium (DMEM medium supplemented with 10% (v/v) fetal bovine serum, 1% (v/v) penicillin, streptomycin) for 1 h, bovine mammary epithelial cells BMEC in logarithmic growth phase were collected, 5000 cells per well were inoculated on the surface of the product, cultured in a 37°C incubator for 4 h, then 20 uL of MTT (5 mg/mL) was added, continued to culture for 4 h and then 100 uL of DMSO was added to each well. After dissolution, the UV absorption value was measured at 490 nm to evaluate the cell adhesion performance. The results are shown in FIG. 3. It can be seen from FIG. 3 that the addition of dopamine significantly improves the adhesion performance of the product.

[87] The in vitro anti-tumor activities of the products prepared in Example 1,

Comparative Example 1 and Comparative Example 2 were tested: Complete medium was added to a 96-well plate, liver cancer HepG2 cells and human breast cancer MCF- 7 cells in logarithmic growth phase were collected, 5000 cells per well were inoculated in a 96-well plate. After 24h, products prepared in Example 1, Comparative Example 1 and Comparative Example 2 after freeze-drying at different concentrations (5ug/mL, 10ug/mL, 20pg/mL, 30ug/mL, 40ug/mL, 50ug/mL) were added. No product was added to the control group. 20uL of MTT (5mg/mL ) was added at 44h, respectively. After 4h of culture, 100uL of DMSO was added to each well. After dissolution, the UV absorbance was measured at 490nm. The cell survival rate and cell inhibition rate were calculated at different concentrations according to Formula IT and Formula HI, and the results are shown in FIG. 4:

[88] Cell survival rate %=(A-K){D-K):100% formula II;

[89] Cell inhibition rate%=1- cell survival rate % _ formula HI;

[90] Wherein A is the absorbance of the experimental group with administration, D is the absorbance of the control group of complete medium inoculated with cancer cells without administration, and K is the absorbance of the group of complete medium without inoculation of cancer cells.

[91] It can be seen from FIG. 4 that when the concentration of the product prepared in

Comparative Example 2 reaches 50 pg/mL, the cell survival rate is still above 80%. The inhibitory effect of the product prepared in Comparative Example 1 on liver cancer

HepG2 cells and human breast cancer MCF-7 cells is greatly improved. The product prepared in Example 1 has a more significant inhibitory effect on liver cancer HepG2 cells and human breast cancer MCF-7 cells than the product prepared in Comparative

Example 1, and as the concentration increases, the inhibitory effect is more obvious, and it has excellent anti-tumor activity. It shows that the dopamine-coated cellulose nanocrystals can increase the drug-loading rate of the drug-loaded hydrogel and further improve the anti-tumor activity.

[92] In summary, the dopamine-coated cellulose nanocrystal-agarose drug-loaded hydrogels prepared by the present disclosure have excellent drug-loading stability and high drug-loading rate, which can realize the loading, targeted release and sustained release of anti-tumor drugs, and have excellent anti-tumor activity.

[93] The above are only the preferred embodiments of the present disclosure. It should be pointed out that for those of ordinary skill in the art, without departing from the principle of the present disclosure, several improvements and modifications can be made, and these improvements and modifications should also be regarded as the protection scope of the present disclosure.

Claims

Conclusions l. Method of preparing a drug-loaded hydrogel comprising dopamine-coated cellulose nanocrystal agarose, the method comprising the following steps: (1) mixing dopamine hydrochloride, water and sodium hydroxide to conduct a polymerization reaction to obtain a polydopamine solution; (2) mixing the polydopamine solution obtained in step (1) with a carboxycellulose nanocrystal, and carrying out a condensation reaction to obtain a dopamine-coated cellulose nanocrystal; (3) mixing the dopamine-coated cellulose nanocrystal obtained in step (2) with a surfactant, water, a drug and agarose, heating and then cooling to form the drug-loaded hydrogel containing dopamine-coated cellulose nanocrystal-agarose includes.

The method of claim 1, wherein the mass ratio of dopamine hydrochloride to sodium hydroxide in step (1) is (4 -5):1.

The method according to claim 1, wherein the mass ratio of the carboxycellulose nanocrystal in the step (2) to dopamine hydrochloride in the step (1) is (1-3}:T.

The method of claim 1, wherein the surfactant in step (3) comprises one of hexadexylamine, octadecylamine and cetyltrimethylammonium bromide.

The method of claim 1, wherein the mass ratio of the dopamine-coated nanocrystal to the surfactant in the step (3) is 1:(2 — 4)

is.

The method of claim 1, wherein the drug in step (3) comprises paclitaxel or adriamycin.

The method of claim 1, wherein the mass ratio of the dopamine-coated cellulose nanocrystal to the drug in the step (3) is 1:(1 - 6).

The method of claim 1, wherein the mass ratio of the dopamine-coated cellulose nanocrystal to the agarose in the step (3) is 1:(3 - 6).

The method of claim 1, wherein the ratio of the mass of dopamine-coated cellulose nanocrystal to the volume of water in the step (3) is 1 mg:(0.1 - 0.5) mL.

A drug-loaded hydrogel comprising dopamine-coated cellulose nanocrystal agarose prepared by the method of any one of claims 1 to 9.