CN118854411A - Preparation method and application of anti-gravity perfusion electrophoretic deposition coating on porous implant surface - Google Patents

Abstract

The invention discloses a preparation method and application of an anti-gravity pouring type electrophoretic deposition coating on the surface of a porous implant, and relates to the technical field of surface modification of porous implants. The method comprises pre-treating an electrically conductive porous implant; obtaining an electrophoresis liquid; in the electrophoresis liquid, taking a conductive porous implant as a cathode, taking a stainless steel ring as an anode, and performing anti-gravity pouring type electrophoresis deposition on the surface of the porous implant under a constant current mode, namely preparing a coating on the surface of the porous implant; the nano-particles with the core-shell structure take mesoporous silica as a shell and silver nano-rods as cores, and the mesoporous silica coated silver nano-rod nano-particles with the core-shell structure are formed. The invention adopts antigravity pouring type electrophoretic deposition to carry out electrophoretic deposition on the pore wall of the porous implant body, and finally obtains the uniformly deposited and high-adhesion composite coating with excellent photo-thermal performance, photo-thermal stability, wettability, antibacterial performance and cell compatibility.

Description

A method for preparing an anti-gravity perfusion electrophoretic deposition coating on the surface of a porous implant and its application

Technical Field

The invention relates to the technical field of porous implant surface modification, and in particular to a preparation method and application of an anti-gravity perfusion electrophoretic deposition coating on the surface of a porous implant.

Background Art

Orthopedic implants represented by titanium alloys are widely used in various orthopedic applications such as fracture fixation, hip replacement and dentistry due to their excellent mechanical properties, good corrosion resistance and excellent biocompatibility. However, due to the high elastic modulus and insufficient osteogenic ability, traditional solid implants generally have problems such as poor bone integration and stress shielding in clinical repair. In order to solve the above problems, the design of porous implant materials came into being. The use of implants with porous structures can avoid "stress shielding" and effectively promote bone integration, and has great development potential in the field of bone repair. However, after the porous substrate is implanted, there are still insufficient biological activities such as insufficient bone induction ability, low neovascularization induction activity and poor antibacterial performance, which in turn cause related surgical complications and bring great hidden dangers to the safety of implant use.

In recent years, the research on improving the biological activity of porous materials by surface modification has gradually increased, but its complex pore structure poses a severe challenge to the development of a bioactive coating process with uniform coating of the inner and outer pore walls and high adhesion. In the prior art, chemical vapor deposition is used to prepare high-performance medical tantalum coatings on the surface of porous titanium, but this preparation method usually requires reaction under high temperature conditions, the process is relatively complicated, the equipment requirements are high and the maintenance cost is high. At the same time, the prior art has also developed a method for preparing tantalum coatings on the surface of porous titanium implants, but the preparation time is relatively long, which leads to serious diffusion of alloy elements and the inability to prepare pure tantalum coatings with uniform composition. The technicians in this field pre-treat the porous tantalum by pickling to form an in-situ growth film layer with bioactive substances on the surface of the material, and then immerse the pre-treated porous tantalum implant material in an electrolyte for micro-arc oxidation treatment, and finally perform hydrothermal treatment for 12 to 24 hours to obtain a porous tantalum implant with good biological properties. However, the preparation method is relatively complicated and difficult to implement. Technicians in this field have also developed a method for preparing a hollow mesoporous silica nanoparticle coating on the surface of porous titanium, but this preparation method is relatively complicated and has a long preparation cycle, and is difficult to operate in practice.

In summary, the current porous material surface preparation technology has the problems of high cost, complex preparation process, poor interface bonding between coating and substrate, and poor internal coverage of porous structure. Therefore, it is necessary to develop a method for simply constructing a bioactive coating with uniform deposition, strong adhesion and multifunctionality on the surface of porous materials, so as to promote the practical application of porous implants in clinical practice.

Summary of the invention

In view of the deficiencies in the above-mentioned background technology, the present invention mainly solves the problems that the existing surface modification methods have high preparation costs and it is difficult to construct uniformly deposited, highly adherent and multifunctional bioactive coatings on the inner and outer surfaces of porous substrates. The present invention provides a preparation method and application of a counter-gravity perfusion electrophoretic deposition coating on the surface of a porous implant. The method uses counter-gravity perfusion electrophoretic deposition to perform electrophoretic deposition on the pore walls of a porous implant, and explores the influence of deposition time, deposition current, and electrophoretic liquid flow rate on the morphology, immersion depth, and coating thickness of the coating, and finally obtains a composite coating with uniform deposition, high adhesion, excellent photothermal performance, photothermal stability, wettability, antibacterial properties, and cell compatibility.

The first object of the present invention is to provide a method for preparing an anti-gravity perfusion electrophoretic deposition coating on the surface of a porous implant, characterized in that it comprises the following steps:

Pre-treating the conductive porous implant;

dissolving acetic acid and chitosan in a water solvent and mixing them evenly to obtain an electrophoresis solution;

In the electrophoretic liquid, the conductive porous implant is used as the cathode and the stainless steel ring is used as the anode. Under the constant current mode, a circular electric field is formed on the surface of the porous implant, and anti-gravity perfusion electrophoretic deposition is performed on the surface of the porous implant, that is, a coating is prepared on the surface of the porous implant.

Preferably, the material of the conductive porous implant includes porous titanium material, porous tantalum material, porous magnesium material, porous carbon material or porous graphite material.

Preferably, the anti-gravity perfusion electrophoretic deposition is performed by using a peristaltic pump as a power source for the electrophoretic liquid to overcome gravity, and the electrophoretic liquid is perfused against gravity, so that the inside and outside of the conductive porous implant can be filled with the electrophoretic liquid and the electrophoretic liquid in the electric field area can be continuously renewed;

During electrophoretic deposition, the distance between the stainless steel ring and the surface of the conductive porous implant is 0.8-1.5 cm, the applied current is 12-24 mA, the electrophoretic deposition time is 2.5-10 min, and the electrophoretic fluid perfusion speed is 0-14 mL/min.

Preferably, the conductive porous implant is pretreated, comprising: using acetone, anhydrous ethanol or deionized water to perform ultrasonic treatment on the conductive porous implant for 15 to 20 minutes respectively.

Preferably, the concentration of chitosan in the electrophoresis solution is 0.5-1.5 mg/mL.

Preferably, the electrophoresis solution further comprises nanoparticles of a core-shell structure, wherein the concentration of the nanoparticles of the core-shell structure is 0.25-1 mg/mL;

The nanoparticles with core-shell structure are mesoporous silica-coated silver nanorod nanoparticles with core-shell structure, with mesoporous silica as shell and silver nanorod as core.

Preferably, in the mesoporous silica-coated silver nanorod nanoparticles having a core-shell structure, the length of the silver nanorod is 80-120 nm, and the aspect ratio is 4.16±0.13;

The thickness of the mesoporous silica shell is 10~80nm.

Preferably, the mesoporous silica is further doped with metal ions; the metal ion doping mass percentage is 1% to 10%; and the metal ions include copper ions.

The second object of the present invention is to provide an anti-gravity perfusion electrophoretic deposition coating on the surface of a porous implant.

The third object of the present invention is to provide an application of the above coating in surface modification of porous implants.

Compared with the prior art, the present invention has the following beneficial effects:

The present invention provides a method for preparing and applying an anti-gravity perfusion electrophoretic deposition coating on the surface of a porous implant. The anti-gravity perfusion electrophoretic deposition coating provided by the present invention drives the electrophoretic liquid to overcome gravity and radiate continuously outward from the inside of the porous implant from bottom to top by external force, thereby achieving uniform distribution of particle concentration inside and outside the pores during the deposition process, promoting the deposition of the coating inside the porous implant, and constructing a uniform and strongly bonded bioactive coating on the surface of the porous material.

The present invention adopts the control variable method to determine the optimal deposition parameters of the anti-gravity perfusion electrophoretic deposition coating on the porous material, and obtains a thicker coating on the surface and shallow surface of the porous material. The coating is uniformly attached to the porous support without obvious cracks and microscopic defects.

The present invention adopts a gold seed method to prepare silver nanorods, uses CTAB as a template agent, and TEOS as a silicon source, and prepares an ion-doped mesoporous silica-wrapped silver nanorod composite material by a sol-gel method. The deposited composite coating has excellent photothermal properties, and can induce local heating of the coating under the irradiation of NIR light, thereby achieving controlled release of silver ions and copper ions and avoiding toxic side effects caused by sudden ion release.

The invention has a simple process, low requirements on instruments, strong applicability, and can meet the preparation of surface coatings of different porous implant materials. The surface morphology and coating thickness of the coating can be adjusted as needed by adjusting the electrophoretic deposition parameters and the content of nanoparticles, thereby controlling the biological properties of the porous implant coating.

The present invention uses anti-gravity perfusion electrophoretic deposition to carry out electrophoretic deposition on the pore walls of porous implants, and explores the influence of deposition time, deposition current, and electrophoretic liquid flow rate on the morphology, immersion depth, and coating thickness of the coating, ultimately obtaining a composite coating with uniform deposition, high adhesion, excellent photothermal properties, photothermal stability, wettability, antibacterial properties, and cell compatibility.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG1 is a schematic diagram of the preparation process of the anti-gravity perfusion electrophoretic deposition coating.

FIG. 2 shows the coating thickness and immersion depth of the anti-gravity perfusion electrophoretic deposition on the outside of the porous titanium stent at different deposition times and currents in Example 1.

FIG. 3 shows the coating thickness and immersion depth of the anti-gravity perfusion electrophoretic deposition on the outside of the porous titanium stent at different electrophoretic fluid flow rates in Example 2.

FIG4 is an optical photograph of AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings prepared on the porous titanium surface by anti-gravity perfusion electrophoretic deposition under optimal deposition parameters in Example 6.

Figure 5 is an electron microscope image of the porous titanium cross-section of AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings prepared on the porous titanium surface by anti-gravity perfusion electrophoretic deposition under the optimal deposition parameters in Example 6.

FIG6 is a coating adhesion test of Example 6 in which the coating is deposited on the surface of a 1 cm×3 cm titanium sheet under optimal deposition parameters.

FIG. 7 is a water contact angle test experiment of Example 6 in which the coating is deposited onto the surface of a 1 cm×3 cm titanium sheet under optimal deposition parameters.

FIG8 is a thermogravimetric analysis of the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings of Example 6.

FIG9 shows the photothermal properties of the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings of Example 6.

Figure 10 shows the ion release behavior of the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings of Example 6.

Figure 11 shows the in vitro antibacterial properties of the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings of Example 6.

FIG. 12 shows the cell compatibility of the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings of Example 6.

DETAILED DESCRIPTION

In order to enable those skilled in the art to better understand and implement the technical solution of the present invention, the present invention is further described below in conjunction with specific embodiments and drawings, but the embodiments are not intended to limit the present invention.

In view of the problems existing in the surface modification of porous implants, the present invention develops an anti-gravity perfusion electrophoretic deposition device, which drives the electrophoretic liquid to overcome gravity from the bottom to the top of the porous implant and continuously radiate outward, so as to achieve uniform distribution of particle concentration inside and outside the pores during the deposition process, and promote the deposition of the internal coating of the porous material. The operation method is simple and controllable, and because chitosan (CTS) is a cationic ion in an acidic aqueous solution and has excellent film-forming properties, it can be combined with inorganic (nano) particles to improve the biological interface of medical implants. The prepared core-shell structured copper-doped mesoporous silica nanoparticles coated with silver nanorods (AgNR@MSN-Cu) nanoparticles exhibit excellent antibacterial properties due to the synergistic antibacterial effect of copper and silver ions. Its ultraviolet-near infrared-visible light absorption spectrum has a higher absorption peak near 808nm, and can produce excellent photothermal effect under NIR light irradiation. The local temperature rise brought by the photothermal effect can not only assist antibacterial, but also promote the release of silver ions and copper ions, and realize the controlled release of ions. Therefore, AgNR@MSN-Cu particles and chitosan were used as raw materials and co-deposited on the surface of the porous material by anti-gravity perfusion electrophoretic deposition. Both AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings showed good wettability, adhesion, photothermal properties and antibacterial properties, which were beneficial to the adhesion and proliferation of osteoblasts. The incorporation of copper ions not only improved the antibacterial properties of the coating, but also promoted the activity of HUVECs cells.

The main purpose of the present invention is to provide a method for preparing a coating deposited on the surface of a porous implant by anti-gravity perfusion electrophoretic deposition. Specifically, a 316L stainless steel ring is set as an anode at a distance of 1 cm from the porous implant, and a conductive porous implant is used as a cathode, so as to form a circular electric field around the porous implant, and the electrophoretic liquid is driven by external force to overcome gravity and continuously radiate outward from the inside of the porous implant from bottom to top, so as to achieve uniform distribution of particle concentration inside and outside the pores during the deposition process, and promote the deposition of the coating inside the porous implant.

The first aspect of the present invention provides a method for preparing a coating on the surface of a porous implant by anti-gravity perfusion electrophoretic deposition, comprising the following steps:

Pre-treating the conductive porous implant;

dissolving acetic acid and chitosan in a water solvent and mixing them evenly to obtain an electrophoresis solution;

In the electrophoretic liquid, the conductive porous implant is used as the cathode and the stainless steel ring is used as the anode. Under the constant current mode, a circular electric field is formed on the surface of the porous implant, and anti-gravity perfusion electrophoretic deposition is performed on the surface of the porous implant, that is, a coating is prepared on the surface of the porous implant.

The material of the conductive porous implant includes porous titanium material, porous tantalum material, porous magnesium material, porous carbon material or porous graphite material.

The anti-gravity perfusion electrophoretic deposition uses a peristaltic pump as a power source for the electrophoretic fluid to overcome gravity, and performs anti-gravity perfusion of the electrophoretic fluid, so that the inside and outside of the conductive porous implant can be filled with the electrophoretic fluid and the electrophoretic fluid in the electric field area can be continuously renewed.

During electrophoretic deposition, the distance between the stainless steel ring and the surface of the conductive porous implant is 0.8-1.5 cm, the applied current is 12-24 mA, the electrophoretic deposition time is 2.5-10 min, and the electrophoretic fluid perfusion speed is 0-14 mL/min.

Among them, the stainless steel ring is a 316L stainless steel ring.

The conductive porous implant is pretreated by using acetone, anhydrous ethanol or deionized water to perform ultrasonic treatment on the conductive porous implant for 15 to 20 minutes respectively.

The mesoporous silica is also doped with metal ions; the metal ion doping mass percentage is 1% to 10%; the metal ions include copper ions.

It should be noted that the LSPR absorption peak of silver nanorods (AgNR) is located near 810 nm. After being coated with the shell of mesoporous silica (MSN) and mesoporous silica doped with copper ions (MSN-Cu), the LSPR peak is red-shifted.

The chitosan concentration in the electrophoresis solution is 0.5-1.5 mg/mL.

The electrophoresis solution also includes nanoparticles with a core-shell structure; the concentration of the nanoparticles with a core-shell structure is 0.25-1 mg/mL.

The core-shell structured nanoparticles are mesoporous silica as a shell and silver nanorods as a core, forming mesoporous silica-coated silver nanorod nanoparticles with a core-shell structure;

In the mesoporous silica-coated silver nanorod nanoparticles having a core-shell structure, the length of the silver nanorod is 80-120 nm, and the aspect ratio is 4.16±0.13;

The thickness of the mesoporous silica shell is 10~80nm.

According to the present invention, a coating (AgNR@MSN-CTS) prepared by using core-shell structured mesoporous silica-coated silver nanorod nanoparticles and a coating (AgNR@MSN-Cu-CTS) prepared by using core-shell structured mesoporous silica-coated silver nanorod nanoparticles doped with copper ions exhibit excellent photothermal properties under near-infrared light irradiation with a wavelength of about 808 nm.

In one embodiment, a method for preparing a coating on a porous material surface by anti-gravity perfusion electrophoretic deposition is provided, comprising the following steps:

Step 1, prepare core-shell structured mesoporous silica nanoparticles coated with silver nanorods (AgNR@MSN) and core-shell structured mesoporous silica nanoparticles doped with copper ions coated with silver nanorods (AgNR@MSN-Cu) nanoparticles: ① prepare silver nanorods (AgNR) by gold seed method; ② prepare core-shell structured photothermal responsive multifunctional nanoparticles (AgNR@MSN and AgNR@MSN-Cu) by sol-gel method.

The method for preparing silver nanorods by the gold seed method comprises: preparing a gold seed solution; adding the gold seed solution to a growth aqueous solution containing CTAB, HAuCl ₄ , AgNO ₃ , HCl and AA, and obtaining a gold bipyramid after standing for reaction; adding a solution of AgNO ₃ and AA to a gold bipyramid solution containing CTAC, and reacting to obtain silver nanorods wrapped with the gold bipyramid; wherein, in the reaction solution, the molar ratio of AA to Ag ⁺ is 3 to 5:1.

Specifically, the specific preparation method of the silver nanorods wrapped with gold bipyramids is as follows:

1.1) At room temperature, HAuCl ₄ (50 mM, 0.05 mL), citric acid (5 mM, 1 mL), and sodium borohydride (25 mM, 0.25 mL) were added to the CTAC (50 mM, 8.95 mL) solution in sequence to prepare gold seeds. After vigorous stirring at room temperature for 2 min, the solution was moved to an 80°C water bath and heated for 90 min with gentle stirring to obtain a gold seed solution, the color of which gradually changed from brown to red. Finally, the seed solution was stored at room temperature. The gold seed solution was used to grow small gold bipyramids.

1.2) At room temperature, HAuCl ₄ (50 mM, 0.2 mL), AgNO ₃ (10 mM, 0.2 mL), HCl (1 M, 0.4 mL) and ascorbic acid (100 mM, 0.16 mL) were added to a CTAB (100 mM, 20 mL) solution in sequence to prepare a gold bipyramid growth solution, which was now colorless. Subsequently, 1 mL of the gold seed solution was taken and added to the gold bipyramid growth solution, and the mixture was allowed to stand at 30 °C for 4 h to obtain a gold bipyramid. The solution was centrifuged (10000 rpm, 30 min) to remove excess reagents and redispersed in CTAC (10 mM, 1 mL).

1.3) Under vigorous stirring, the solution of AgNO ₃ (10 mM) and AA (100 mM) was added to the gold bipyramid (10 mL) solution containing CTAC (10 mM) at room temperature. During the entire addition process, the molar ratio [AA]: [Ag ⁺ ] = 4 was kept constant. After the addition was completed, the mixture was vigorously stirred at 60 ° C for 2 h. Finally, the resulting solution was centrifuged (10000 rpm, 30 min) and redispersed in water to obtain silver nanorods.

It should be noted that the length and aspect ratio of the bipyramid can be changed to meet different needs by changing the concentration ratio of silver nitrate and gold.

The sol-gel method for preparing the core-shell structured photothermal responsive multifunctional AgNR@MSN and AgNR@MSN-Cu nanoparticles comprises:

The prepared silver nanorods were dispersed in a chloroform solution, and then added into a CTAB aqueous solution to obtain a homogeneous oil-in-water microemulsion;

After evaporating the chloroform in the obtained microemulsion, the AgNR@CTAB solution was obtained;

The AgNR@CTAB solution is added into an alkaline aqueous solution containing CTAB. After the reaction is completed, photothermal responsive multifunctional ion-doped nanoparticles with a core-shell structure are obtained.

In one embodiment, the preparation method of mesoporous silica nanoparticles coated with silver nanorods (AgNR@MSN) having a core-shell structure is as follows:

2.1) Add CHCl ₃ solution to the prepared silver nanorod solution to prepare a mixed solution with a target concentration of 5 mg/mL, add CTAB solution (5 mM, 2 mL) to it under vigorous stirring and mix it evenly. Then, move the mixture to 65 ° C and heat it for 20 min to remove CHCl ₃ to obtain AgNR@CTAB solution, and add 86 mL of it to an aqueous solution containing CTAB (1.5 mM) and NaOH (16 mM, 0.7 mL) at room temperature and mix evenly.

2.2) The above solution was moved to 80°C, and 1 mL of TEOS was slowly added under vigorous stirring and reacted for 2 h. After the reaction, the excess reagent was removed by centrifugation (10000 rpm, 10 min) and the product was collected. The sample was added to an ethanol solution (6 g/L) containing NH ₄ NO ₃ and extracted for 24 h to remove the remaining template in the product. After the extraction, the product was washed alternately with deionized water and anhydrous ethanol for 6 times, and the product was collected and dried to obtain mesoporous silica nanoparticles coated with silver nanorods (AgNR@MSN) with a core-shell structure.

Specifically, the preparation method of the copper ion-doped mesoporous silica nanoparticles coated with silver nanorods (AgNR@MSN-Cu) nanoparticles having a core-shell structure is as follows:

2.3) At room temperature, Cu(NO ₃ ) ₂ ·3H ₂ O was added to 0.1 mL of anhydrous ethanol to prepare an ethanol solution containing Cu(NO ₃ ) ₂ ·3H ₂ O. The mass of Cu(NO ₃ ) 2 ·3H ₂ O was calculated based on the molar percentage of Cu(NO 3 ) ₂ ·3H 2 O and the added TEOS. 1% Cu means that the molar percentage of Cu(NO ₃ ) ₂ ·3H ₂ O:TEOS is 1%. Similarly, solutions with different copper ion doping amounts were prepared. 0.25 mL of TEOS was slowly added dropwise thereto and stirred for 15 min to obtain Cu-TEOS.

2.4), similar to 2.2), the mixture containing AgNR was moved to 80°C, and Cu-TEOS was first slowly added under vigorous stirring, and then 0.75mL TEOS solution was slowly added, and the reaction was carried out for 2h. After the reaction was completed, the excess reagent was removed by centrifugation (10000rpm, 10min), and the product was collected. The sample was added to an ethanol solution (6g/L) containing NH ₄ NO ₃ and extracted for 24h to remove the remaining template in the product. After the extraction was completed, the product was washed alternately with deionized water and anhydrous ethanol for 6 times, and the product was collected and dried to obtain mesoporous silica nanoparticles doped with copper ions with a core-shell structure and coated with silver nanorods.

In one embodiment, when preparing Cu-TEOS, the molar percentage of Cu(NO ₃ ) ₂ ·3H ₂ O:TEOS is 1%, and the prepared copper ion-doped mesoporous silica nanoparticles with a core-shell structure coated with silver nanorods are referred to as AgNR@MSN-1%Cu;

When preparing Cu-TEOS, the molar percentage of Cu(NO ₃ ) ₂ ·3H ₂ O:TEOS is 3%, and the prepared copper ion-doped mesoporous silica nanoparticles coated with silver nanorods with a core-shell structure are referred to as AgNR@MSN-3%Cu;

Among them, the template was removed by extraction with ethanol solution containing NH ₄ NO ₃ for 24 h in order to remove CTAB with cytotoxicity in the MSN pores.

Step 2, preparation and treatment of porous implants: Prepare porous samples of different substrates, and then use acetone, anhydrous ethanol or deionized water to ultrasonically treat different porous implants for 15 minutes each for subsequent use.

Step 3, prepare the electrophoresis fluid: first, add 1.5 mL of acetic acid to 45 mL of deionized water, mix well, add 150 mg of chitosan to the solution and stir for 10 min to fully dissolve the chitosan, then slowly add 103.5 mL of anhydrous ethanol to the solution under vigorous stirring to obtain a chitosan solution with a final concentration of 1 mg/mL; next, add the prepared core-shell structured nanoparticles to the solution to prepare an electrophoresis fluid, stir the mixture for 5 min, and then ultrasonically treat the electrophoresis fluid for 30 min to evenly disperse the particles to obtain an electrophoresis fluid containing nanoparticles.

Step 4, as shown in FIG1 , anti-gravity perfusion electrophoretic deposition is used to prepare a surface coating: the electrolyte prepared in the third step is used to prepare a coating on the surface of the porous material by anti-gravity perfusion electrophoretic deposition, and a peristaltic pump is used as a power source for the electrophoretic liquid to overcome gravity and to perfuse the electrophoretic liquid against gravity, so that the inside and outside of the porous material can be filled with the electrophoretic liquid and the electrophoretic liquid in the electric field area can be continuously updated. The porous material is used as the cathode, and a 316L stainless steel ring is placed as the anode 1 cm away from the outer surface of the porous substrate, thereby forming a circular electric field on the surface of the porous material. A constant current mode is used to apply a constant current for a period of time.

A second aspect of the present invention provides a counter-gravity perfusion electrophoretic deposition coating on the surface of a porous implant.

The third aspect of the present invention provides a use of the above-mentioned coating in surface modification of porous implants.

It should be noted that the experimental methods used in the present invention are all conventional methods unless otherwise specified; the reagents and materials used are all commercially available unless otherwise specified.

Example 1

A method for preparing a composite coating on the surface of a porous titanium implant comprises the following steps:

Step 1: Preparation and treatment of porous titanium implants: Magics 24.0 was used to design a three-dimensional model of the porous implant. The radius of the porous titanium was 3 mm, the height was 10 mm, and the pore size was 500 μm. The porous titanium sample was then prepared by selective laser melting. The porous titanium was then ultrasonically treated with acetone and anhydrous ethanol for 15 min in turn to remove oil stains on the surface of the porous titanium for subsequent use.

Step 2: First, add 1.5 mL of acetic acid to 45 mL of deionized water, mix well, add 150 mg of chitosan to the solution and stir for 10 min to fully dissolve the chitosan, then slowly add 103.5 mL of anhydrous ethanol to the solution under vigorous stirring to obtain a chitosan solution with a final concentration of 1 mg/mL; next, add 100 mg of MSN to the solution to prepare an electrophoresis solution with a final concentration of 1 mg/mL, stir the mixture for 5 min, and then ultrasonically treat the electrophoresis solution for 30 min to disperse the particles evenly, thereby obtaining an electrophoresis solution containing MSN nanoparticles;

Step 3: Use an electrophoretic solution containing MSN to prepare a coating on the porous titanium surface by anti-gravity perfusion electrophoretic deposition. Use a peristaltic pump as the power source for the electrophoretic solution to overcome gravity and perfuse the electrophoretic solution against gravity, so that the inside and outside of the porous titanium can be filled with electrophoretic solution and the electrophoretic solution in the electric field area can be continuously updated. Use porous titanium as the cathode and place a 316L stainless steel ring as the anode 1 cm away from the outer surface of the porous titanium to form a circular electric field on the porous titanium surface. Use a constant current mode to deposit the coating on the porous titanium surface. The deposition time is 2.5, 5, 7.5 and 10 minutes, respectively, and the deposition current is 12, 16, 20 and 24 mA. Subsequently, the porous titanium is taken out and placed in a cool place to dry naturally, and the corresponding MSN-CTS coatings under different deposition times and different deposition currents are obtained.

Example 1 uses a single variable method to explore the effects of deposition time and deposition current on coating thickness and immersion depth during electrophoretic deposition of a coating on a porous titanium surface.

Example 2

A method for preparing a composite coating on the surface of a porous titanium implant comprises the following steps:

Step 1: Preparation and treatment of porous implants: Magics 24.0 was used to design a three-dimensional model of the porous implant. The radius of the porous titanium was 3 mm, the height was 10 mm, and the pore size was 500 μm. The porous titanium sample was then prepared by selective laser melting. The porous titanium was then ultrasonically treated with acetone and anhydrous ethanol for 15 min in turn to remove oil stains on the surface of the porous titanium for subsequent use.

Step 2: First, add 1.5 mL of acetic acid to 45 mL of deionized water, mix well, add 150 mg of chitosan to the solution and stir for 10 min to fully dissolve the chitosan, then slowly add 103.5 mL of anhydrous ethanol to the solution under vigorous stirring to obtain a chitosan solution with a final concentration of 1 mg/mL; next, add 100 mg of MSN to the solution to prepare an electrophoresis solution with a final concentration of 1 mg/mL, stir the mixture for 5 min, and then ultrasonically treat the electrophoresis solution for 30 min to disperse the particles evenly, thereby obtaining an electrophoresis solution containing MSN nanoparticles;

Step 3: Use electrophoresis fluids containing MSN at different concentrations to prepare coatings on the porous titanium surface by anti-gravity perfusion electrophoretic deposition. Use a peristaltic pump as the power source to overcome gravity and perfuse the electrophoresis fluid, so that the inside and outside of the porous titanium can be filled with electrophoresis fluid and the electrophoresis fluid in the electric field area can be continuously updated. Use porous titanium as the cathode and place a 316L stainless steel ring as the anode 1 cm away from the outer surface of the porous titanium to form a circular electric field on the porous titanium surface. Use a constant current mode to deposit the coating on the porous titanium surface. The deposition current is 20 mA, the deposition time is 5 min, and the electrophoresis fluid flow rate is 0~14 mL/min. Subsequently, take out the porous titanium and place it in a cool place to dry naturally, and obtain the corresponding MSN-CTS coatings at different electrophoresis fluid flow rates.

Example 2 uses a single variable method to explore the effect of electrophoretic liquid flow rate on multi-coating thickness and immersion depth during electrophoretic deposition of coatings on porous titanium surfaces.

Example 3

A method for preparing a composite coating on the surface of a porous carbon implant comprises the following steps:

Step 1: Preparation and treatment of porous carbon implants: A three-dimensional porous carbon scaffold with a radius of 3 mm, a height of 10 mm, and an average pore size of 150 μm was prepared using a sphere template method, and then the porous carbon implant was ultrasonically treated with anhydrous ethanol and deionized water for 15 min in sequence for subsequent use;

Step 2: First, add 1.5 mL of acetic acid to 45 mL of deionized water, mix well, add 150 mg of chitosan to the solution and stir for 10 min to fully dissolve the chitosan, then slowly add 103.5 mL of anhydrous ethanol to the solution under vigorous stirring to obtain a chitosan solution with a final concentration of 1 mg/mL; next, add 100 mg of MSN to the solution to prepare an electrophoresis solution with a final concentration of 1 mg/mL, stir the mixture for 5 min, and then ultrasonically treat the electrophoresis solution for 30 min to disperse the particles evenly, thereby obtaining an electrophoresis solution containing MSN nanoparticles;

Step 3: Use an electrophoretic solution containing MSN to prepare a coating on the porous carbon surface by anti-gravity perfusion electrophoretic deposition. Use a peristaltic pump as the power source for the electrophoretic solution to overcome gravity and perfuse the electrophoretic solution against gravity, so that the inside and outside of the porous carbon can be filled with electrophoretic solution and the electrophoretic solution in the electric field area can be continuously updated. Use the porous carbon as the cathode, and place a 316L stainless steel ring as the anode 1 cm away from the outer surface of the porous carbon to form a circular electric field on the porous carbon surface. Use a constant current mode to deposit the coating on the porous carbon surface. The deposition time is 2.5, 5, 7.5 and 10 minutes, respectively. The deposition current is 12, 16, 20 and 24 mA, and the electrophoretic solution flow rate is 0~14mL/min. Subsequently, the porous carbon is taken out and placed in a cool place to dry naturally to obtain the MSN-CTS coating.

Example 3 uses a single variable method to explore the effects of deposition time, deposition current and electrophoretic liquid flow rate on coating thickness and immersion depth during the process of depositing a coating on a porous carbon surface by anti-gravity perfusion electrophoretic deposition.

Example 4

A method for preparing a composite coating on the surface of a porous tantalum implant comprises the following steps:

Step 1: Preparation and treatment of porous tantalum implants: A three-dimensional porous tantalum scaffold with a radius of 3 mm, a height of 10 mm, and a pore size of 500 μm was prepared by selective laser melting. The porous tantalum implant was then ultrasonically treated with acetone, anhydrous ethanol, and deionized water for 15 min each to remove impurities on its surface for subsequent use.

Step 2: First, add 1.5 mL of acetic acid to 45 mL of deionized water, mix well, add 150 mg of chitosan to the solution and stir for 10 min to fully dissolve the chitosan, then slowly add 103.5 mL of anhydrous ethanol to the solution under vigorous stirring to obtain a chitosan solution with a final concentration of 1 mg/mL; next, add 100 mg of MSN to the solution to prepare an electrophoresis solution with a final concentration of 1 mg/mL, stir the mixture for 5 min, and then ultrasonically treat the electrophoresis solution for 30 min to disperse the particles evenly, thereby obtaining an electrophoresis solution containing MSN nanoparticles;

Step 3: Use an electrophoretic solution containing MSN to prepare a coating on the surface of porous tantalum by anti-gravity perfusion electrophoretic deposition. Use a peristaltic pump as the power source for the electrophoretic solution to overcome gravity and perfuse the electrophoretic solution against gravity, so that the inside and outside of the porous tantalum can be filled with electrophoretic solution and the electrophoretic solution in the electric field area can be continuously updated. Use the porous tantalum as the cathode, and place a 316L stainless steel ring as the anode 1 cm away from the outer surface of the porous tantalum to form a circular electric field on the surface of the porous tantalum. Use a constant current mode to deposit the coating on the surface of the porous tantalum. The deposition time is 2.5, 5, 7.5 and 10 minutes, respectively. The deposition current is 12, 16, 20 and 24 mA, and the electrophoretic solution flow rate is 0~14mL/min. Subsequently, the porous tantalum is taken out and placed in a cool place to dry naturally to obtain the MSN-CTS coating.

Example 4 uses a single variable method to explore the effects of deposition time, deposition current and electrophoretic liquid flow rate on coating thickness and immersion depth during the process of depositing a coating on a porous tantalum surface by counter-gravity perfusion electrophoretic deposition.

Example 5

A method for preparing a photothermal responsive multifunctional composite coating on the surface of a porous titanium implant comprises the following steps:

Step 1: Prepare silver nanorods by the gold seed method described above;

Step 2: Prepare core-shell structured AgNR@MSN nanoparticles by the sol-gel method described above;

Step 3: Preparation and treatment of porous titanium implants: Magics 24.0 was used to design the three-dimensional model of the porous titanium implant. The radius of the porous titanium was 3 mm, the height was 10 mm, and the pore size was 500 μm. The porous titanium sample was then prepared by the selective laser melting method. The porous titanium was then ultrasonically treated with acetone and anhydrous ethanol for 15 min in turn to remove oil stains on the surface of the porous titanium for subsequent use.

Step 4: First, 1.5 mL of acetic acid was added to 45 mL of deionized water, and after mixing, 150 mg of chitosan was added to the solution and stirred for 10 min to fully dissolve the chitosan. Then, 103.5 mL of anhydrous ethanol was slowly added to the solution under vigorous stirring to obtain a chitosan solution with a final concentration of 1 mg/mL; Next, 0, 25, 50, and 100 mg of AgNR@MSN nanoparticles were added to the solution to prepare electrophoresis solutions with final concentrations of 0, 0.25, 0.5, and 1 mg/mL, respectively. After the mixture was stirred for 5 min, the electrophoresis solution was ultrasonically treated for 30 min to disperse the particles evenly, and electrophoresis solutions containing different concentrations of AgNR@MSN nanoparticles were obtained;

Step 5: Use electrophoretic fluids containing different concentrations of AgNR@MSN nanoparticles to prepare coatings on the porous titanium surface by anti-gravity perfusion electrophoretic deposition. A peristaltic pump is used as a power source for the electrophoretic fluid to overcome gravity and to perfuse the electrophoretic fluid against gravity, so that the inside and outside of the porous titanium can be filled with electrophoretic fluid and the electrophoretic fluid in the electric field area can be continuously updated. The porous titanium is used as the cathode, and a 316L stainless steel ring is placed 1 cm away from the outer surface of the porous titanium as the anode, thereby forming a circular electric field on the porous titanium surface. In Examples 1 and 2, the effects of deposition current, deposition time, and electrophoretic fluid flow rate on the coating thickness and coating immersion depth on the porous titanium surface were explored by the single variable method, and the optimal deposition parameters were determined: the deposition current was 20 mA, the deposition time was 5 min, and the electrophoretic fluid flow rate was 6 mL/min. The coating was deposited on the porous titanium surface under this parameter in constant current mode. Subsequently, the porous titanium was taken out and placed in a cool place to dry naturally to obtain different AgNR@MSN-CTS, which were named Bare PT, 0.25 PT, 0.5 PT and 1.0 PT coatings respectively.

In Example 5, under the optimal deposition parameters: deposition current of 20 mA, deposition time of 5 min, and electrophoretic liquid flow rate of 6 mL/min, a composite coating containing AgNR@MSN nanoparticles of different concentrations was prepared on the porous titanium surface by anti-gravity perfusion electrophoretic deposition.

Example 6

A method for preparing a photothermal responsive multifunctional composite coating on the surface of a porous titanium implant comprises the following steps:

Step 1: Prepare silver nanorods by the gold seed method described above;

Step 2: Prepare core-shell structured AgNR@MSN and AgNR@MSN-Cu nanoparticles with different copper ion doping amounts by the sol-gel method described above;

Step 3: Preparation and treatment of porous titanium implants: Magics 24.0 was used to design the three-dimensional model of the porous titanium implant. The radius of the porous titanium was 3 mm, the height was 10 mm, and the pore size was 500 μm. The porous titanium sample was then prepared by the selective laser melting method. The porous titanium was then ultrasonically treated with acetone and anhydrous ethanol for 15 min in turn to remove oil stains on the surface of the porous titanium for subsequent use.

Step 4: First, add 1.5 mL of acetic acid to 45 mL of deionized water, mix well, add 150 mg of chitosan to the solution and stir for 10 min to fully dissolve the chitosan. Then, slowly add 103.5 mL of anhydrous ethanol to the solution under vigorous stirring to obtain a chitosan solution with a final concentration of 1 mg/mL; Next, add 100 mg of AgNR@MSN, AgNR@MSN-1%Cu and AgNR@MSN-3%Cu nanoparticles to the solution, stir the mixture for 5 min, and then ultrasonically treat the electrophoresis solution for 30 min to disperse the particles evenly, and obtain electrophoresis solutions containing different AgNR@MSN-Cu nanoparticles;

Step 5: Use electrophoretic solutions containing AgNR@MSN, AgNR@MSN-1%Cu and AgNR@MSN-3%Cu respectively, and prepare coatings on the porous titanium surface by anti-gravity perfusion electrophoretic deposition. Use a peristaltic pump as the power source for the electrophoretic solution to overcome gravity and perfuse the electrophoretic solution against gravity, so that the inside and outside of the porous titanium can be filled with electrophoretic solution and the electrophoretic solution in the electric field area can be continuously updated. Use porous titanium as the cathode, and place a 316L stainless steel ring as the anode 1 cm away from the outer surface of the porous titanium, so as to form a circular electric field on the porous titanium surface. Use constant current mode to deposit the coating on the porous titanium surface, with a deposition current of 20 mA, a deposition time of 5 min, and an electrophoretic solution flow rate of 6 mL/min. Subsequently, the porous titanium was taken out and placed in a cool place to dry naturally to obtain AgNR@MSN-CTS (abbreviated as Ag-CTS), AgNR@MSN-1Cu-CTS (abbreviated as 1%Cu-CTS) and AgNR@MSN-3Cu-CTS (abbreviated as 3%Cu-CTS) coatings, respectively.

Example 6 is a composite coating containing different AgNR@MSN-Cu nanoparticles prepared on the porous titanium surface by anti-gravity perfusion electrophoretic deposition under the optimal deposition parameters: deposition current of 20 mA, deposition time of 5 min and electrophoretic liquid flow rate of 6 mL/min.

In order to illustrate the relevant properties of the composite coating provided by the present invention, reference is made to FIGS. 2 to 12 for illustration.

Figure 2 shows the coating thickness and immersion depth of the anti-gravity perfusion electrophoretic deposition on the outside of the porous titanium stent at different deposition times and currents as described in Example 1 of the present invention. It can be seen from the figure that when the deposition current is 20 mA and the deposition time is 5 min, it is sufficient to deposit a coating with sufficient thickness on the surface of the porous titanium stent, and the immersion depth of the coating has also reached the maximum value.

Figure 3 shows the coating thickness and immersion depth of the anti-gravity perfusion electrophoretic deposition on the outside of the porous titanium stent at different electrophoretic fluid flow rates as described in Example 2 of the present invention. It can be seen from the figure that when the electrophoretic fluid flow rate is less than 6mL/min, the coating thickness will increase with the increase of the electrophoretic fluid flow rate, and the depth of the coating entering the porous titanium stent will also become deeper with the increase of the electrophoretic fluid flow rate; when the electrophoretic fluid flow rate exceeds 6mL/min, the coating thickness and the depth of the coating entering the porous titanium stent will both decrease with the increase of the electrophoretic fluid flow rate. Therefore, combined with the results in the figure, it can be concluded that the most suitable electrophoretic fluid flow rate is 6mL/min.

Figure 4 is an optical photograph of the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings prepared on the porous titanium surface by anti-gravity perfusion electrophoretic deposition under the optimal deposition parameters described in Example 6 of the present invention. It can be seen from the photo that a relatively uniform coating composed of chitosan and AgNR@MSN, AgNR@MSN-1%Cu or AgNR@MSN-3%Cu is produced by the anti-gravity perfusion electrophoretic deposition process, covering the surface of the porous titanium and entering a part of the porous structure inside the porous titanium.

Figure 5 is an electron microscope image of a porous titanium cross section of AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings prepared on the porous titanium surface by anti-gravity perfusion electrophoretic deposition under the optimal deposition parameters described in Example 6 of the present invention. It can be seen from the figure that according to the selected optimal process parameters, a thicker coating is obtained on the porous titanium surface and the shallow surface layer, and the coating is evenly attached to the porous titanium support without obvious cracks and microscopic defects.

Figure 6 is a test of the adhesion of the coating deposited on the surface of a 1 cm × 3 cm titanium sheet under the optimal deposition parameters described in Example 6 of the present invention. The tape test results show that the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings have good adhesion to the titanium substrate, and the presence of the chitosan matrix enables the AgNR@MSN, AgNR@MSN-1%Cu and AgNR@MSN-3%Cu nanoparticles to adhere firmly to the surface of the Ti substrate.

Figure 7 is a water contact angle test experiment of depositing the coating onto the surface of a 1 cm×3 cm titanium sheet under the optimal deposition parameters described in Example 6 of the present invention. The test results show that after surface modification, the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings on the surface of the pure titanium substrate greatly improve the wettability of the titanium substrate.

Figure 8 is a thermogravimetric analysis of the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings described in Example 6 of the present invention. From the thermal decomposition process of the AgNR@MSN-CTS and AgNR@MSN-CTS composite coatings, it can be seen that the content of particles in the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings can be adjusted by changing the mass ratio of nanoparticles to pure CTS in the EPD suspension, thereby giving the composite coatings pre-designed antibacterial properties.

Figure 9 shows the photothermal performance of the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings described in Example 6 of the present invention. Figures AC show the temperature changes and corresponding thermal imaging images of the samples Ag-CTS, 1%Cu-CTS and 3%Cu-CTS irradiated with NIR light of different power densities (0.5, 1 and ^2W /cm2), and Figure D shows the irradiation of Ag-CTS, 1%Cu-CTS and 3%Cu-CTS with NIR light of power density of 1W/ ^cm2 for five "on/off" cycles. It can be seen from the figure that the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings have excellent photothermal performance and photothermal stability.

Figure 10 shows the ion release behavior of the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings described in Example 6 of the present invention. It can be seen from the figure that at each time point of NIR light irradiation, the silver ion and copper ion release curves in the figure will produce obvious steps, and the steps represent the amount of copper ions and silver ions released under NIR light irradiation, which indicates that NIR light irradiation can significantly promote the release of ions in AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings, not only promoting the release of silver ions in the silver core, but also promoting the release of copper ions in the MSN shell.

Figure 11 shows the in vitro antibacterial properties of the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings described in Example 6 of the present invention. The results in the figure show that: thanks to the broad-spectrum antibacterial properties of silver ions, the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings exhibit good antibacterial properties against both Gram-positive and Gram-negative bacteria without NIR light irradiation, and with the incorporation of copper ions, copper ions and silver ions synergistically antibacterial, so that the antibacterial properties of the AgNR@MSN-Cu-CTS composite coating are improved, and the higher the copper ion doping amount, the more obvious the performance improvement. In addition, when the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings are irradiated with NIR light, their antibacterial efficiency will also be improved.

Figure 12 shows the cell compatibility of the AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings described in Example 6 of the present invention. Figure A shows the activity of MC3T3-E1 osteoblasts co-cultured with Ag-CTS, 1%Cu-CTS and 3%Cu-CTS composite coatings, Figure B shows the activity of MC3T3-E1 osteoblasts co-cultured with NIR light (808nm) with a power density of 1W/ ^cm2 for 5 minutes in the initial stage of co-culture of cells and materials, and Figure C shows the activity of HUVECs cells co-cultured with Ag-CTS, 1%Cu-CTS and 3%Cu-CTS composite coatings. The results show that AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings on porous titanium have good cell compatibility with MC3T3-E1 osteoblasts, and cells can proliferate rapidly on the porous titanium surface. In addition, the incorporation of copper ions also improved the bioactivity of the coating and could enhance the activity of HUVECs cells.

In an embodiment of the present invention, both AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings exhibit good wettability, are conducive to the adhesion and proliferation of osteoblasts, and have good bonding with the titanium substrate. In addition, AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings also have good photothermal effects and stability. Under the irradiation of NIR light, local heating of the coating can be triggered, triggering the release of Ag ⁺ and Cu ²⁺ . This synergistic effect of controllable photothermal triggered ion release has an effective bactericidal effect on Escherichia coli and Staphylococcus aureus. In vitro experiments have confirmed that AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings have good cell compatibility for MC3T3-E1 osteoblasts and HUVECs cells, and cells can proliferate rapidly on the surface of porous titanium implants. AgNR@MSN-CTS and AgNR@MSN-Cu-CTS composite coatings can enhance antibacterial properties by NIR light irradiation, while only causing limited cytotoxicity. In addition, the incorporation of copper ions also enhances the bioactivity of the coatings and can improve the activity of HUVECs cells.

The present invention describes preferred embodiments and their effects. However, those skilled in the art may make additional changes and modifications to these embodiments once they are aware of the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims (10)

1. The preparation method of the anti-gravity pouring type electrophoretic deposition coating on the surface of the porous implant is characterized by comprising the following steps of:

Pretreating the conductive porous implant;

Dissolving acetic acid and chitosan in a water solvent, and uniformly mixing to obtain an electrophoresis liquid;

In the electrophoresis liquid, the conductive porous implant is used as a cathode, a stainless steel ring is used as an anode, an annular electric field is formed on the surface of the porous implant in a constant current mode, and antigravity pouring type electrophoresis deposition is performed on the surface of the porous implant, namely, a coating is prepared on the surface of the porous implant.

2. The method for preparing the surface antigravity poured electrophoretic deposition coating of the porous implant according to claim 1, wherein the conductive porous implant comprises porous titanium material, porous tantalum material, porous magnesium material, porous carbon material or porous graphite material.

3. The method for preparing the surface antigravity pouring type electrophoretic deposition coating of the porous implant according to claim 1, wherein the antigravity pouring type electrophoretic deposition is carried out by taking a peristaltic pump as a power source for overcoming gravity of the electrophoretic liquid, so that the inside and the outside of the conductive porous implant can be filled with the electrophoretic liquid and the electrophoretic liquid in the electric field area can be continuously updated;

During electrophoretic deposition, the distance between the stainless steel ring and the surface of the conductive porous implant is 0.8-1.5cm, the applied current is 12-24mA, the electrophoretic deposition time is 2.5-10min, and the electrophoretic liquid pouring speed is 0-14mL/min.

4. The method for preparing the surface antigravity poured electrophoretic deposition coating of the porous implant according to claim 1, wherein the conductive porous implant is pretreated, comprising: and respectively carrying out ultrasonic treatment on the conductive porous implant for 15-20 min by using acetone, absolute ethyl alcohol or deionized water.

5. The method for preparing the surface antigravity pouring type electrophoretic deposition coating of the porous implant according to claim 1, wherein the concentration of chitosan in the electrophoresis liquid is 0.5-1.5 mg/mL.

6. The method for preparing the surface antigravity pouring type electrophoretic deposition coating of the porous implant according to claim 1, wherein the electrophoretic fluid further comprises core-shell nano particles, and the concentration of the core-shell nano particles is 0.25-1 mg/mL;

The nano-particles with the core-shell structure take mesoporous silica as a shell and silver nano-rods as cores, and the mesoporous silica coated silver nano-rod nano-particles with the core-shell structure are formed.

7. The method for preparing the anti-gravity pouring type electrophoretic deposition coating on the surface of the porous implant according to claim 6, wherein the mesoporous silica with the core-shell structure is used for coating silver nanorod nano particles, the length of the silver nanorod is 80-120 nm, and the length-diameter ratio is 4.16+/-0.13;

the thickness of the mesoporous silica shell layer is 10-80 nm.

8. The method for preparing the surface antigravity poured electrophoretic deposition coating of the porous implant according to claim 7, wherein the mesoporous silica is further doped with metal ions; the metal ion doping mass percentage is 1% -10%; the metal ions include copper ions.

9. A porous implant surface antigravity poured electrophoretic deposition coating made by the method of any one of claims 1-8.

10. Use of the coating of claim 9 for surface modification of porous implants.