阅读说明：本技术 与植入体强结合兼具抗菌耐蚀性纳米复合涂层及制备方法 (Nano composite coating with strong combination with implant and antibacterial and corrosion resistance and preparation method thereof ) 是由 胡勇 胡永淇 李申申 张会莹 张昊 褚成 王力华 于 2021-08-22 设计创作，主要内容包括：与植入体强结合兼具抗菌耐蚀性纳米复合涂层及制备方法,纳米复合涂层包括耐蚀结合层和抗菌层；抗菌层是单独的纳米氧化锌涂层,或是单独的氧化石墨烯涂层,或是纳米氧化锌和氧化石墨烯组合涂层。方法为：(1)在植入体的表面制备PDA涂层；(2)在步骤(1)所得植入体表面制备GO涂层,得到与植入体强结合并兼具抗菌和耐蚀性能的聚多巴胺-氧化石墨烯纳米复合涂层；(3)在步骤(1)所得植入体表面制备纳米ZnO涂层,得到与植入体强结合并兼具抗菌和耐蚀性能的聚多巴胺-纳米氧化锌纳米复合涂层；(4)在步骤(3)所得植入体表面制备GO涂层,得到与植入体强结合并兼具抗菌和耐蚀性能的聚多巴胺-纳米氧化锌-氧化石墨烯纳米复合涂层。(The nanometer composite coating which is strongly combined with an implant and has antibacterial and corrosion-resistant properties and a preparation method thereof, wherein the nanometer composite coating comprises a corrosion-resistant combined layer and an antibacterial layer; the antibacterial layer is an independent nano zinc oxide coating, or an independent graphene oxide coating, or a nano zinc oxide and graphene oxide combined coating. The method comprises the following steps: (1) preparing a PDA coating on the surface of the implant; (2) preparing a GO coating on the surface of the implant obtained in the step (1) to obtain a polydopamine-graphene oxide nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistant properties; (3) preparing a nano ZnO coating on the surface of the implant obtained in the step (1) to obtain a polydopamine-nano zinc oxide nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistant properties; (4) and (4) preparing a GO coating on the surface of the implant obtained in the step (3) to obtain a polydopamine-nano zinc oxide-graphene oxide nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistant properties.)

1. The nano composite coating which is strongly combined with an implant and has antibacterial and corrosion-resistant properties is characterized by comprising a corrosion-resistant combined layer and an antibacterial layer; the corrosion-resistant bonding layer is a polydopamine coating-PDA coating; the antibacterial layer is an independent nano zinc oxide coating-ZnO coating, or an independent graphene oxide coating-GO coating, or a nano zinc oxide-ZnO and graphene oxide-GO combined coating.

2. The nanocomposite coating with antibacterial and corrosion resistance combined with an implant according to claim 1, wherein the thickness of the PDA coating is 1-50nm, the thickness of the nano ZnO coating is 10-160nm, the thickness of the GO coating is 0.1-2.0nm, the thickness of the nano ZnO and GO combined coating is 10.1-162.0nm, and the nano ZnO coating is positioned below the GO coating.

3. The nanocomposite coating with antibacterial and corrosion resistance for strong bonding to an implant according to claim 1, wherein the number of layers of the nanocomposite coating is 2-3, preferably 2.

4. The nanocomposite coating with antibacterial and corrosion resistance combined with an implant according to claim 1, wherein the corrosion-resistant combined layer is a PDA coating, and the antibacterial layer is one or a combination of a nano ZnO coating and a GO coating.

5. The method for preparing the nanocomposite coating with strong combination with an implant and antibacterial and corrosion resistance according to claim 1, comprising the steps of:

step (1) preparing a PDA coating on the surface of an implant;

step (2) preparing a GO coating on the surface of the implant obtained in the step (1) to obtain a polydopamine-graphene oxide nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistant properties, namely a GP nano composite coating;

step (3) preparing a nano ZnO coating on the surface of the implant obtained in the step (1) to obtain a polydopamine-nano zinc oxide nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistance, namely a ZP nano composite coating;

and (4) preparing a GO coating on the surface of the implant obtained in the step (3) to obtain a polydopamine-nano zinc oxide-graphene oxide nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistant properties, namely a GZP nano composite coating.

6. The method for preparing the nanocomposite coating with antibacterial and corrosion resistance combined with the implant according to claim 5, wherein the implant in the step (1) is made of medical metal, including stainless steel, cobalt alloy, titanium alloy, shape memory alloy, noble metal, pure metal or a combination of at least two of them, preferably titanium alloy.

7. The method for preparing the nanocomposite coating with antibacterial and corrosion resistance combined with an implant according to claim 5, wherein the method for preparing the PDA coating in step (1) is a solution oxidation method, wherein trihydroxyaminomethane hydrochloride is firstly used to prepare a buffer solution, dopamine hydrochloride is then added, under a suitable temperature and alkaline environment, dopamine monomer can undergo a self-polymerization reaction in an alkaline solution to form the PDA coating, and oxygen is used as an oxidant.

8. The method for preparing the nanocomposite coating with strong combination with an implant and antibacterial and corrosion resistance according to claim 5, wherein the method for preparing the GP nanocomposite coating in the step (2) is a GO suspension coating method, and comprises the following specific steps:

transferring a product obtained by adopting an improved Hummers method to a centrifuge tube, adding dilute hydrochloric acid and deionized water, alternately centrifuging for four times, cleaning the centrifuge tube with the deionized water for three times, pouring the centrifuge tube into a culture dish, carrying out freeze drying and vacuum drying on the centrifuged product, and finally grinding the centrifuged product into powder;

adding a certain amount of powder obtained in the step (1) into deionized water in a sub-step (2) for ultrasonic dispersion, and then centrifuging in a centrifuge to prepare GO suspension with a preset concentration;

and (3) transferring the GO suspension obtained in the step (2) to the surface of the implant coated with the PDA layer in the step (1) in a dripping mode, and then placing the implant in a vacuum drying oven to dry for a period of time to obtain the GP nano composite coating.

9. The method for preparing the nanocomposite coating with antibacterial and corrosion resistance combined with implant according to claim 5, wherein the method for preparing the ZP nanocomposite coating in the step (3) is a seedless hydrothermal method; preparing zinc nitrate and hexamethylenetetramine into solutions with the same concentration, and uniformly mixing and stirring; putting the implant obtained in the step (1) into a mixed solution at a proper temperature, quickly heating to a preset temperature, reacting for a period of time to obtain a colorless transparent solution, washing with deionized water, and drying at a preset drying temperature for a period of time to obtain a ZP nano composite coating;

the method for preparing the GZP nano composite coating in the step (4) is a seed crystal-free hydrothermal method and a GO suspension coating method, and the GZP nano composite coating is obtained by coating GO suspension on the basis of the step (3).

Technical Field

The invention belongs to the technical field of metal material surface modification, and relates to a preparation technology of a nano composite coating.

Background

With the increasing damage of hard tissues caused by diseases or accidental injuries, titanium alloy as an artificial bone substitute has attracted great attention in the field of implantation medicine due to its excellent biocompatibility and good mechanical properties. The development of the additive manufacturing technology enables the processing of the porous titanium alloy, and the technology also effectively solves the problem of stress shielding existing in the titanium alloy implant. However, titanium alloy as a permanent hard tissue implant must have the combination of antibacterial, corrosion-resistant and bone cell growth promoting properties while considering its mechanical properties. The design of the surface modified coating plays an important role in optimizing the service performance of the titanium alloy.

The antibiotic is introduced to the surface of the titanium alloy to achieve the bactericidal effect, but the action time of the antibiotic is limited, and the antibiotic is easy to cause drug resistance. Compared with antibiotics, Graphene Oxide (GO) and nano zinc oxide (nano ZnO) belong to a novel antibacterial agent. Kachoei and other researches show that the nano zinc oxide nano coating has good antibacterial and friction-resistant performances on the surface of the nickel-titanium alloy. Azam et al believe that nano-zinc oxide exhibits strong antibacterial activity against both gram-positive and gram-negative bacteria, and its antibacterial activity increases as the size of the nano-zinc oxide decreases. Nanda et al found that GO can be induced by Escherichia coliAnd degradation of the cell membrane of enterococcus faecalis leading to bacterial death. Wang et al indicate that the GO/nano ZnO composite material has high antibacterial efficiency, and the low-concentration nano ZnO and GO have no obvious cytotoxicity. At the same time, GO is coupled with Zn²⁺The ion dissolution rate has a regulating effect, and is an ideal long-term antibacterial material. However, how to further improve the firm chemical bonding between the GO/nano ZnO composite material and the substrate while fully exerting the comprehensive performance of the GO/nano ZnO composite material is a research hotspot in the fields of coating design and surface modification.

Inspired by the adhesion phenomenon of marine mussels in nature, dopamine is considered to be the best substitute material of the bionic binder because the structure of dopamine contains catechol groups and amino functional groups of lysine. The dopamine can generate oxidation-crosslinking reaction in aqueous solution to form a polydopamine film which is firmly attached to the surface of the material. Cheng et al prepared a nano ZnO coating with excellent antibacterial property on a PET film by a hydrothermal method without seed crystal intervention with PDA as an anchoring agent of the clustered nano ZnO particles. The preparation of the multifunctional bioceramic coating needs to select a proper preparation process method and also needs to select materials with excellent performance, the nano inorganic antibacterial agent becomes the optimal selection of the antibacterial material due to safe, harmless and stable antibacterial performance, and the nano zinc oxide has the performance of the inorganic antibacterial agent, and the zinc element is taken as a human body trace element, so that the synthesis of metal enzyme in a human body can be promoted, the regeneration of body tissues can be promoted, and the biological ceramic coating can participate in the immune process to finally improve the autoimmune capability.

Disclosure of Invention

The invention aims to provide a nano composite coating which is strongly combined with an implant and has antibacterial and corrosion resistant properties and a preparation method thereof.

The invention relates to a nano composite coating which is strongly combined with an implant and has antibacterial and corrosion-resistant properties and a preparation method thereof, wherein the nano composite coating which is strongly combined with the implant and has antibacterial and corrosion-resistant properties comprises a corrosion-resistant combined layer and an antibacterial layer; the corrosion-resistant bonding layer is a polydopamine coating-PDA coating; the antibacterial layer is an independent nano zinc oxide coating-ZnO coating, or an independent graphene oxide coating-GO coating, or a nano zinc oxide-ZnO and graphene oxide-GO combined coating.

The invention relates to a preparation method of a nano composite coating which is strongly combined with an implant and has antibacterial and corrosion resistant properties, which comprises the following steps:

step (1) preparing a PDA coating on the surface of an implant;

step (2) preparing a GO coating on the surface of the implant obtained in the step (1) to obtain a polydopamine-graphene oxide nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistant properties, namely a GP nano composite coating;

step (3) preparing a nano ZnO coating on the surface of the implant obtained in the step (1) to obtain a polydopamine-nano zinc oxide nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistance, namely a ZP nano composite coating;

and (4) preparing a GO coating on the surface of the implant obtained in the step (3) to obtain a polydopamine-nano zinc oxide-graphene oxide nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistant properties, namely a GZP nano composite coating.

Compared with the prior art, the invention has the following beneficial effects: the provided nano composite coating which is strongly combined with an implant and has antibacterial and corrosion resistant properties can effectively prolong the service life of the coating, and the surface antibacterial elements are nano-sized, so that the coating has strong activity and better antibacterial effect. The thickness and the composition of the antibacterial coating and the corrosion-resistant bonding coating are combined and proportioned, so that the release speed of the antibacterial element is moderate, the bonding layer does not influence the release of the antibacterial element and the exertion of antibacterial performance under the conditions, and the cell proliferation is promoted, so that the coating is an ideal coating for implantable medical devices.

The nano composite coating which is strongly combined with an implant and has antibacterial and corrosion resistant properties provided by the invention has the advantages of low preparation cost, simple process and capability of large-area rapid preparation on the surface of a complex structure.

Drawings

Fig. 1 is a flowchart of a method for preparing a nanocomposite coating layer strongly bonding to an implant and having antibacterial and corrosion resistant properties according to the present invention, fig. 2 is a graph of antibacterial results of a PDA coating layer, fig. 3 is a graph of antibacterial results of example 1 of the present invention, fig. 4 is a graph of antibacterial results of comparative example 3, fig. 5 is a graph of antibacterial results of example 2 of the present invention, fig. 6 is a graph of antibacterial results of example 3 of the present invention, fig. 7 is a Nyquist impedance curve of example 1 of the present invention, fig. 8 is a polarization curve of example 2 of the present invention, fig. 9 is a Nyquist impedance curve of example 2 of the present invention, fig. 10 is a polarization curve of example 2 of the present invention, and fig. 11 is a Nyquist impedance curve of example 3 of the present invention; FIG. 12 is a polarization curve of example 3 of the present invention.

Detailed Description

The invention relates to a nano composite coating which is strongly combined with an implant and has antibacterial and corrosion-resistant properties and a preparation method thereof, wherein the nano composite coating which is strongly combined with the implant and has antibacterial and corrosion-resistant properties comprises a corrosion-resistant combined layer and an antibacterial layer; the corrosion-resistant bonding layer is a polydopamine coating-PDA coating; the antibacterial layer is an independent nano zinc oxide coating-ZnO coating, or an independent graphene oxide coating-GO coating, or a nano zinc oxide-ZnO and graphene oxide-GO combined coating.

The nano composite coating adopts the design of layer-by-layer assembly to form a unique sandwich structure. Has the characteristics of simple manufacture and application to the surface of an implant with a complex structure.

The thickness of the PDA coating is 1-50nm, the thickness of the nano ZnO coating is 10-160nm, the thickness of the GO coating is 0.1-2.0nm, the thickness of the nano ZnO and GO combined coating is 10.1-162.0nm, and the position of the nano ZnO coating is below the GO coating.

In the nano composite coating, the number of layers of the nano composite coating is 2-3, preferably 2.

The anti-corrosion combined layer of the nano composite coating is a PDA coating, and the antibacterial layer is one or the combination of a nano ZnO coating and a GO coating.

The invention relates to a preparation method of a nano composite coating which is strongly combined with an implant and has antibacterial and corrosion resistant properties, which comprises the following steps:

step (1) preparing a PDA coating on the surface of an implant;

step (2) preparing a GO coating on the surface of the implant obtained in the step (1) to obtain a polydopamine-graphene oxide nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistant properties, namely a GP nano composite coating;

step (3) preparing a nano ZnO coating on the surface of the implant obtained in the step (1) to obtain a polydopamine-nano zinc oxide nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistance, namely a ZP nano composite coating;

and (4) preparing a GO coating on the surface of the implant obtained in the step (3) to obtain a polydopamine-nano zinc oxide-graphene oxide nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistant properties, namely a GZP nano composite coating.

In the preparation method, the implant in step (1) is a medical metal, including one or a combination of at least two of stainless steel, cobalt alloy, titanium alloy, shape memory alloy, precious metal and pure metal, preferably a titanium alloy.

In the preparation method, the method for preparing the PDA coating in the step (1) is a solution oxidation method, and first, trihydroxyaminomethane hydrochloride is used to prepare a buffer solution, then dopamine hydrochloride is added, and under a suitable temperature and an alkaline environment, the dopamine monomer can perform a self-polymerization reaction in an alkaline solution to form the PDA coating, and oxygen is an oxidant.

In the preparation method, the method for preparing the GP nano composite coating in the step (2) is a GO suspension coating method, and the preparation method specifically comprises the following steps:

transferring a product obtained by adopting an improved Hummers method to a centrifuge tube, adding dilute hydrochloric acid and deionized water, alternately centrifuging for four times, cleaning the centrifuge tube with the deionized water for three times, pouring the centrifuge tube into a culture dish, carrying out freeze drying and vacuum drying on the centrifuged product, and finally grinding the centrifuged product into powder;

adding a certain amount of powder obtained in the step (1) into deionized water in a sub-step (2) for ultrasonic dispersion, and then centrifuging in a centrifuge to prepare GO suspension with a certain concentration;

and (3) transferring the GO suspension obtained in the step (2) to the surface of the implant coated with the PDA layer in the step (1) in a dripping mode, and then placing the implant in a vacuum drying oven to dry for a period of time to obtain the GP nano composite coating.

In the preparation method, the method for preparing the ZP nano composite coating in the step (3) is a hydrothermal method without seed crystal; preparing zinc nitrate and hexamethylenetetramine into solutions with the same concentration, and uniformly mixing and stirring; placing the implant obtained in the step (1) into a mixed solution at a proper temperature, rapidly heating to a certain temperature, reacting for a period of time to obtain a colorless transparent solution, washing with deionized water, and drying at a certain drying temperature for a period of time to obtain a ZP nano composite coating;

the method for preparing the GZP nano composite coating in the step (4) is a seed crystal-free hydrothermal method and a GO suspension coating method, and the GZP nano composite coating is obtained by coating GO suspension on the basis of the step (3).

The invention is further developed as follows: according to the invention, a layer of corrosion-resistant and strongly-combined PDA coating is formed on the surface of the implant by utilizing the chelation of PDA to metal ions and the characteristic of rich functional groups, and then an antibacterial coating is prepared on the PDA coating by adopting three ways, so that a nano composite coating which is strongly combined with the implant and has antibacterial and corrosion-resistant properties is prepared; wherein the mode of preparing the antibacterial coating comprises the following steps: the method comprises the following steps that a coating method is adopted to coat GO suspension liquid with a certain concentration on the surface of a PDA coating, GO is naturally deposited on the surface of the PDA coating to form a poly-dopamine-graphene oxide nano composite coating (GP coating for short), the antibacterial effect of the poly-dopamine-graphene oxide nano composite coating depends on the concentration of the GO suspension liquid, and the GO can play an antibacterial role to the maximum extent by being adjusted to a proper concentration; preparing a nano ZnO coating on the PDA coating by a seedless hydrothermal method to prepare a polydopamine-nano zinc oxide nano composite coating (ZP coating for short), and adjusting the nano ZnO to the optimal form by controlling experimental conditions to achieve a better antibacterial effect; and thirdly, firstly preparing a nano ZnO coating on the PDA coating by a crystal seed-free hydrothermal method, and then coating GO suspension on the basis of the prepared ZP nano composite coating to form a polydopamine-nano zinc oxide-graphene oxide nano composite coating (GZP coating for short), wherein GO can control the precipitation speed of nano zinc oxide, so that the release speed of the antibacterial element is moderate, and the optimal antibacterial performance is achieved under the synergistic action of nano ZnO and GO.

The thickness of the PDA coating is 1-50nm, and can be 1nm, 2nm, 3nm, 4nm, 5nm, 6nm, 7nm, 8nm, 9nm, 10nm, 11nm, 12nm, 13nm, 14nm, 15nm, 16nm, 17nm, 18nm, 19nm, 20nm, 21nm, 22nm, 23nm, 24nm, 25nm, 26nm, 27nm, 28nm, 29nm, 30nm, 31nm, 32nm, 33nm, 34nm, 35nm, 36nm, 37nm, 38nm, 39nm, 40nm, 41nm, 42nm, 43nm, 44nm, 45nm, 46nm, 47nm, 48nm, 49nm and 50nm, preferably 40-50 nm.

The thickness of the nano ZnO coating is 10-160nm, and can be 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, 100nm, 110nm, 120nm, 130nm, 140nm, 150nm and 160nm, preferably 40-120 nm.

The thickness of the GO coating is 0.1-2 nm, and can be 0.1nm, 0.2nm, 0.3nm, 0.4nm, 0.5nm, 0.6nm, 0.7nm, 0.8nm, 0.9nm, 1.0nm, 1.1nm, 1.2nm, 1.3nm, 1.4nm, 1.5nm, 1.6nm, 1.7nm, 1.8nm, 1.9nm and 2.0nm, and preferably 0.5-1.5 nm.

The thickness of the nano ZnO and GO combined coating is 10.5-161.5 nm, and can be 10.5nm, 11nm, 11.5nm, 20.5nm, 21nm, 21.5nm, 30.5nm, 31nm, 31.5nm, 40.5nm, 41nm, 41.5nm, 50.5nm, 51nm, 51.5nm, 60.5nm, 61nm, 61.5nm, 70.5nm, 71nm, 71.5nm, 80.5nm, 81nm, 81.5nm, 90.5nm, 91nm, 91.5nm, 100.5nm, 100nm, 101.5nm, 110.5nm, 111nm, 111.5nm, 120.5nm, 121nm, 121.5nm, 130.5nm, 131nm, 131.5nm, 140.5nm, 141nm, 141.5nm, 150.5nm, 151.5nm, 160.5nm, 161.5nm, preferably 10.5nm, 11 nm-91.5 nm.

The number of the layers of the nano composite coating is 2-3, for example, 2 layers and 3 layers, preferably 2 layers.

The PDA coating can be 1 layer or multiple layers, the nano ZnO coating can be 1 layer or multiple layers, the GO coating can be 1 layer or multiple layers, the combined coating of the nano ZnO and the GO can be 2 layers or multiple layers, the number of the layers of all the coatings can be freely selected according to the specific shape of the implant, the PDA coating is selected to be 1 layer, the nano ZnO coating is 1 layer, the GO coating is 1 layer, the combined coating of the nano ZnO and the GO is 2 layers, and the relative position of the nano ZnO coating is below the GO coating.

In the invention, compared with a method for realizing firm bonding between other substrates and the antibacterial coating by using the PDA coating as a bonding layer, the method for forming the functional and adhesive active coating on the surface layer of the material with a complex structure by using the PDA covalent grafting is more beneficial. The reason is that PDA contains abundant functional groups, shows strong adhesion property in water environment, has no material selectivity, can be adsorbed on the surface of almost any kind, shape and size of material, is convenient to modify the surface of the material, is easy to deposit on the surface of inorganic and organic materials, can obtain good modification effect by simple soaking or infiltration, and can stably exist on the surface of an implant for a long time.

Compared with other antibacterial materials, the nano ZnO and GO used as the antibacterial materials can be degraded in a human body, and the zinc is used as a trace element of the human body, so that the biocompatibility is improved, and the cytotoxicity can be reduced.

Preferably, the antibacterial coating comprises any one of a nano ZnO coating or a GO coating or a combination of the two.

The invention provides a preparation method of the nano coating, which comprises the following steps:

(1) preparing a PDA coating on the surface of the implant;

(2) preparing a GO coating on the surface of the implant obtained in the step (1) to obtain a GP nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistant properties;

(3) preparing a nano ZnO coating on the surface of the implant obtained in the step (1) to obtain a ZP nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistant properties;

(4) preparing a GO coating on the surface of the implant obtained in the step (3) to obtain a GZP nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistant properties;

preferably, the implant in step (1) is a medical metal, including one or a combination of at least two of stainless steel, cobalt alloy, titanium alloy, shape memory alloy, noble metal or pure metal, preferably titanium alloy (Ti 6Al 4V).

The method also comprises pretreatment before the step (1), and specifically comprises the following steps: and cleaning the surface of the implant body to remove attachments on the surface of the implant body.

The cleaning is ultrasonic cleaning of the implant in a solvent for 10-20 min, which can be 10min, 11min, 12 min, 13min, 14min, 15min, 16min, 17min, 18min, 19min and 20min, preferably 15 min.

The solvent comprises acetone, absolute ethyl alcohol and deionized water.

The specific steps of the cleaning are as follows:

(1') ultrasonically cleaning the implant in acetone for 15 min;

(2 ') ultrasonically cleaning the implant obtained in the step (1') in absolute ethyl alcohol for 15 min;

(3 ') ultrasonically cleaning the implant obtained in the step (2') in deionized water for 15 min.

The method for preparing the PDA coating in the step (1) is a solution oxidation method, firstly trihydroxyaminomethane hydrochloride is used for preparing a buffer solution, then dopamine hydrochloride is added, under a proper temperature and alkaline environment, dopamine monomer can carry out self-polymerization reaction in an alkaline solution to form the PDA coating, and oxygen is used as an oxidant.

The amount of the trihydroxyaminomethane hydrochloride is 0.07-0.08 g, which can be 0.0711g, 0.0722g, 0.0733g, 0.0744g, 0.0755g, 0.0766g, 0.0777g, 0.0788g, 0.0799g, 0.0800g, preferably 0.0788 g.

The dosage of the dopamine hydrochloride is 0.05-0.15 g, and can be 0.05g, 0.06g, 0.07g, 0.08g, 0.09g, 0.10g, 0.11g, 0.12g, 0.13g, 0.14g, 0.15g, and preferably 0.10 g.

The pH value of the alkaline environment is 7-9, and can be 7, 7.5, 8, 8.5, 9, preferably 8.5.

The suitable temperature is 15-30 ℃, for example, 15 ℃, 20 ℃, 25 ℃, 30 ℃, preferably 25 ℃.

After the pH of the buffer was adjusted to 8.5, dopamine hydrochloride was added and the pH decreased by about 0.05. Adding dopamine hydrochloride into a buffer solution at 25 ℃ to adjust the pH value to 8.5, measuring the pH value, and finding that the reaction is quicker in the first 30min, the pH value of the solution becomes brown when the pH value is 8.27-8.29, the solution (the pH value is 8.23) becomes brownish black after 40min, the pH value changes in a range of 8.21-8.23 after continuing the reaction for 90min, the pH value is slower after the reaction, the pH value is 8.12 after 13h, the pH value is 8.09 after 16h, and the pH value is 8.04 after the reaction is finished in 24 h. From this, it is presumed that the whole reaction is OH consumption^-Liberation of H⁺Reaction of (1), the reaction consuming H in equilibrium⁺. Therefore, at room temperature (25 ℃), a solution with more abundant oxygen (pH 8.5) is the best condition for preparing PDA coatings.

The specific steps of preparing the GO coating in step (2) are as follows:

(1') transferring a product obtained by adopting an improved Hummers method into a centrifuge tube, adding dilute hydrochloric acid and deionized water, alternately centrifuging for four times, cleaning the centrifuge tube with the deionized water for three times, pouring into a culture dish, performing freeze drying and vacuum drying treatment, and finally grinding into powder;

(2 ') adding a certain amount of powder obtained in the step (1') into deionized water for ultrasonic dispersion, and then centrifuging in a centrifugal machine to prepare GO suspension with a certain concentration;

(3 ') the GO suspension obtained in the step (2') is transferred and drop-cast on the surface of the implant coated with the PDA layer, and then the implant is placed in a vacuum drying oven to be dried for a period of time to obtain a GP nano composite coating;

the diluted hydrochloric acid in step (1') has a HCl to H ratio₂O =1/5~1/15, which may be 1/5, 1/10, 1/15, preferably 1/10.

The temperature of the freeze-drying in step (1') is from-75 ℃ to-90 ℃, and may be-75 ℃, from-80 ℃, from-85 ℃, or from-90 ℃, preferably from-80 ℃.

The freeze drying time in the step (1') is 7-9 h, and may be 7h, 7.5h, 8h, 8.5h, 9h, and preferably 8 h.

The vacuum drying time in the step (1') is 12-48 h, and can be 12h, 24h, 48h, and preferably 24 h.

The time for ultrasonic dispersion in the step (2') is 1-2 h, and can be 1h, 1.5h, 2h, and preferably 1.5 h.

The concentration of graphene oxide in step (2') is 0.10mg/mL, 0.25mg/mL, 0.50mg/mL, preferably 0.10 mg/mL;

the temperature for vacuum drying in step (3') is 35-40 deg.C, and may be, for example, 35 deg.C, 36 deg.C, 37 deg.C, 38 deg.C, 39 deg.C, 40 deg.C, and preferably 37 deg.C.

The pressure of the vacuum drying in the step (3') is 20-30 KPa, for example, 20KPa, 21KPa, 22KPa, 23KPa, 24KPa, 25KPa, 26KPa, 27KPa, 28KPa, 29KPa, 30KPa, preferably 25 KPa.

The vacuum drying time in step (3') is 5-7 h, for example, 5h, 5.5h, 6h, 6.5h, 7h, preferably 6 h.

When the concentration of the coated GO suspension is too high, the GO layer formed on the surface of the PDA coating in the deposition process has more defects, because the water contact angle of the GO coating is increased continuously along with the increase of the concentration, the wettability of the material is reduced, and the surface of the coating has uneven defects; when the concentration is too low, the formed GO coating is not compact enough, and the antibacterial effect is poor; better antibacterial effect can only be achieved when the concentration of GO suspension is proper.

The preparation of the nano ZnO coating in the step (3) comprises the following specific steps:

the nano ZnO coating is prepared by a hydrothermal method without seed crystal, and zinc nitrate and hexamethylenetetramine are prepared into solutions with the same concentration and are stirred and mixed uniformly. And (3) putting the implant body containing the PDA coating into the mixed solution at a proper temperature, quickly heating to a certain temperature, reacting for a period of time to obtain a colorless transparent solution, and washing with deionized water. Drying for a period of time at a certain temperature to obtain the ZP nano composite coating.

The using amount of the zinc nitrate is 0.1-0.3 g, a proper amount of the zinc nitrate is completely dissolved in deionized water to prepare a solution with a certain concentration, and preferably 0.2975g of the zinc nitrate is dissolved in 100mL of deionized water to prepare a 0.01mol/L solution.

The using amount of the hexamethylenetetramine powder (HMT) is 0.05-0.15 g, a proper amount of HMT is completely dissolved in deionized water to prepare a solution with a preset concentration, and preferably 0.1402g of HMT is dissolved in 100mL of deionized water to prepare a 0.01mol/L solution.

The suitable temperature is 50-60 ℃, and can be 50 ℃, 55 ℃, 60 ℃ and preferably 55 ℃.

The temperature is increased to a preset temperature of 80-95 ℃, and the preset temperature can be 80 ℃, 85 ℃, 90 ℃, 95 ℃ and preferably 90 ℃.

The reaction time is 2-3 h, can be 2h, 2.5h and 3h, and is preferably 2.5 h.

The drying temperature is 50-70 ℃, and can be 50 ℃, 55 ℃, 60 ℃, 65 ℃, 70 ℃, and preferably 60 ℃.

The drying time is 5-7 h, and can be 5h, 5.5h, 6h, 6.5h, 7h, preferably 6 h.

The chelation of PDA can enhance the stability of nano ZnO crystal nucleus in the initial reaction stage, and a great amount of fine cluster nano ZnO is formed on the PDA coating. The cluster nano ZnO is in a regular hexagonal prism shape, has higher surface energy and reaction activity, and can release Zn⁺And light-induced generation of H₂O₂And the like, and is favorable for accelerating the attachment and proliferation of osteoblasts on the surface.

The nanocomposite coatings of the present invention can be used in modifying implantable medical devices. The implantable medical device comprises any one or a combination of at least two of a bone nail, a bone plate, a hard tissue substitute, a heart support, an artificial joint or a heart pacemaker.

To further illustrate the technical means and effects of the present invention, the following embodiments further illustrate the technical solutions of the present invention, but the present invention is not limited to the scope of the embodiments.

Example 1:

the flow chart of the preparation method of the nano composite coating is shown in fig. 1, and the preparation method specifically comprises the following steps:

(1) taking the polished titanium alloy (Ti 6Al 4V) as a matrix, and ultrasonically cleaning in acetone, absolute ethyl alcohol and deionized water for 15min respectively;

(2) preparing a PDA coating on the surface of the titanium alloy matrix obtained in the step (1) by adopting a solution oxidation method, wherein the dosage of trihydroxy aminomethane hydrochloride is 0.0788g, the dosage of dopamine hydrochloride is 0.1000g, the pH value of a solution environment is 8.5, the reaction temperature is 25 ℃, and the thickness of the PDA layer is 50 nm; the antibacterial effect of the PDA coating is shown in fig. 2; the corrosion resistance is shown in FIGS. 7 to 12.

(3) Preparing GO powder on the surface of the PDA coating obtained in the step (2) by adopting an improved Hummers method and freeze drying treatment, firstly pre-freezing a product obtained by adopting the improved Hummers method at the temperature of-80 ℃ for 8 hours, then transferring the product to a freeze dryer for treatment for 24 hours, and finally grinding the product into powder;

(4) adding 100mg of GO powder obtained in the step (3) into 1000mL of deionized water, performing ultrasonic dispersion for 1.5h, and centrifuging in a centrifuge for 15min to prepare a GO solution of 0.10 mg/mL;

(5) transferring 0.25mL of 0.10mg/mL GO suspension obtained in the step (4) to the surface of the titanium alloy substrate coated with the PDA layer, and then placing the titanium alloy substrate in a vacuum drying oven to dry for 6 hours at 37 ℃ and under a 25KPa environment to obtain a 0.10-GP nano composite coating (representing the GP nano composite coating coated with 0.10mg/mL GO suspension); the antibacterial effect is shown in fig. 3, and the corrosion resistance results are shown in fig. 7 and 8.

Example 2:

the flow chart of the preparation method of the nano composite coating is shown in fig. 1, and the preparation method specifically comprises the following steps:

(1) taking the polished titanium alloy (Ti 6Al 4V) as a matrix, and ultrasonically cleaning in acetone, absolute ethyl alcohol and deionized water for 15min respectively;

(2) PDA coatings were prepared in the same manner as in example 1;

(3) preparing the nano ZnO coating on the surface of the PDA coating obtained in the step (2) by a seedless hydrothermal method, and mixing 0.2975g Zn（NO₃）₂·6H₂O and 0.1402g of Hexamethylenetetramine (HMT) powder are respectively dissolved in 100mL of deionized water to prepare a solution with the concentration of 0.01 mol/L;

(4) pouring the solution obtained in the step (3) into Zn (NO) at the temperature of 55 DEG C₃）₂Uniformly stirring and mixing the solution, then putting the titanium alloy substrate coated with the PDA coating into the solution, quickly heating the solution to a preset temperature of 90 ℃, changing the solution from colorless to turbid along with the rise of the solution temperature, reacting for 2.5 hours until the solution is in a colorless transparent state, washing the titanium alloy substrate by using deionized water, and drying for 6 hours at 60 ℃ to obtain a ZP nano composite coating; the antibacterial effect is shown in fig. 5, and the corrosion resistance results are shown in fig. 9 and 10.

Example 3:

the flow chart of the preparation method of the nano composite coating is shown in fig. 1, and the preparation method specifically comprises the following steps:

(1) taking the polished titanium alloy (Ti 6Al 4V) as a matrix, and ultrasonically cleaning in acetone, absolute ethyl alcohol and deionized water for 15min respectively;

(2) PDA coatings were prepared in the same manner as in example 1;

(3) preparing a ZP nano composite coating in the same way as in example 2;

(4) and (4) preparing the GZP nano composite coating by coating GO suspension on the surface of the ZP nano composite coating obtained in the step (3). 0.25mL of 0.1mg/mL GO solution is dripped on the surface of the ZP nano composite coating, and vacuum drying is carried out for 6h at 37 ℃ and 25KPa, so as to obtain a 0.10-GZP nano composite coating (representing the GZP nano composite coating coated with 0.10mg/mL GO suspension liquid); the antibacterial effect is shown in fig. 6, and the corrosion resistance results are shown in fig. 11 and 12.

Comparative example 1:

compared with example 1, the conditions are the same as example 1 except that the GO antibacterial coating is not added.

Comparative example 2:

compared to example 1, except that the concentration of GO suspension was 0.25mg/mL, a 0.25-GP nanocomposite coating was prepared, with the other conditions being the same as example 1.

Comparative example 3:

compared with example 1, except that the concentration of GO suspension is 0.50mg/mL, 0.50-GP nanocomposite coating is prepared, the antibacterial result is shown in FIG. 4, and other conditions are the same as example 1.

Comparative example 4:

in comparison with example 3, except that the concentration of GO suspension was 0.25mg/mL, a 0.25-GZP nanocomposite coating was prepared, and the conditions were the same as in example 3.

Comparative example 5:

compared to example 3, except that the concentration of GO suspension was 0.50mg/mL, a 0.50-GP nanocomposite coating was prepared, with the other conditions being the same as example 3.

The corrosion result of the nano composite coating shows that:

in example 1, the GO coating has a synergistic corrosion resistance with the PDA coating. The 0.10-GP sample has the best corrosion resistance, which shows that the GO layer formed by the low-concentration GO suspension has few defects and better barrier capability to corrosive ions. The corrosion performance result shows that the corrosion resistance of the GZP sample is obviously improved compared with that of the ZP sample, on one hand, the wettability of the coating is reduced due to the existence of the GO layer, and on the other hand, the GO layer can block the contact of corrosive ions and a base metal interface.

In example 3, GO, nano ZnO and PDA layers showed synergistic corrosion resistance. The low-concentration GZP nano composite coating has better corrosion resistance, and in the comparative example 5, the high-concentration 0.50-GZP nano composite coating shows poorer corrosion resistance than other coatings due to more defects of a GO layer.

The antibacterial result of the nano composite coating shows that the antibacterial rate is calculated according to the plate bacteria number result in the graph. Antibacterial rate = (number of colonies in control group-number of colonies in experimental group) ÷ number of colonies in control group × 100%.

In example 1, the GP nanocomposite coating had a significant antimicrobial effect compared to the PDA layer, the antimicrobial rate was positively correlated to GO concentration, with increasing concentration, the antimicrobial rate increased from 0.10-90.1% of the GP nanocomposite coating under the incubator light source to 99.1% of the 0.50-GP nanocomposite coating in the comparative example.

In example 2, the ZP nanocomposite coating had a bactericidal effect of 97% or more on e. The GZP nanocomposite coating has a significant antibacterial effect compared to the PDA layer in comparative example 1, but the sterilization rate of e.coli is reduced to about 87% compared to the ZP nanocomposite coating because the GO layer traps bacterial liquid and does not completely contact nano ZnO, whereas the low-concentration GO in example 1 has a weak sterilization effect. Meanwhile, the composite coating nano ZnO plays a main antibacterial role.

Testing the binding force of the nano composite coating:

the results of the ultrasonic vibration tests of examples 1-3 are shown in Table 1:

the change in mass of the samples before and after the oscillation was measured by the ultrasonic oscillation method, and as can be seen from table 1, the mass was measured five times before and after each group of samples, and the average value was taken. The PDA coating was found to be slightly degraded by testing under heat sonication, due to the loss of some physically bound dopamine in the SBF solution (simulated body fluid). Since the sample itself had a small mass and the mass of the sample after deposition of the PDA was unchanged at 0.1mg compared to the mass of the substrate, the mass of the sample before and after sonication after 0.1mg was retained.

After weighing each sample five times by using a precision analytical balance, putting the sample into a conical flask filled with SBF solution, plugging a plug, putting the conical flask into an ultrasonic cleaning instrument, starting heating, adjusting the ultrasonic frequency to 40 kHz, after ultrasonic oscillation for 30min, washing the sample with ultrapure water, drying the sample, weighing the sample again, weighing the sample five times, comparing the mass average values before and after ultrasonic treatment, wherein the mass loss is a certain loss, but the mass loss of the sample coated with nano ZnO on the PDA is relatively reduced compared with the mass loss of the sample directly coated with nano ZnO on the substrate, and the difference value in the table 1 shows that the PDA indeed enhances the bonding force of the nano ZnO coating and the substrate.

In conclusion, through the structural design of layer-by-layer assembly, the nano zinc oxide and the graphene oxide are used as the combined antibacterial agent, and the chelating effect of the polydopamine on metal ions is utilized to prepare the nano composite coating which is strongly combined with the implant and has antibacterial and corrosion resistant properties on the surface of the implant. The nano composite coating consists of a corrosion-resistant bonding coating and an antibacterial coating, wherein the corrosion-resistant bonding coating is a polydopamine coating; the antibacterial coating is one or the combination of two of a nano zinc oxide coating and a graphene oxide coating. The nano composite coating has simple preparation process, has comprehensive effects of antibiosis, corrosion resistance and strong combination with a matrix, and is an ideal coating applied to surface modification of an implant with a complex structure.

The present invention is illustrated in detail by the examples described above, but the present invention is not limited to the details described above, i.e., it is not intended that the present invention be implemented by relying on the details described above. It should be understood by those skilled in the art that any modification of the present invention, equivalent substitutions of the raw materials of the product of the present invention, addition of auxiliary components, selection of specific modes, etc., are within the scope and disclosure of the present invention.