A long-acting antibacterial blood compatibility surface modified double-layer structure material and a preparation method and application thereof

Abstract

The present application relates to the technical field of medical device surface modification, and in particular to a surface modification material, a preparation method and application thereof. The surface modification material comprises a substrate, an antibacterial bottom layer and a blood compatibility surface layer arranged in sequence from the surface of the substrate outward; the antibacterial bottom layer is a cross-linked polymer formed by a multifunctional monomer containing at least two olefinic unsaturated bonds and at least one carboxyl group (or a carboxyl hydrolysis precursor), and loaded with a positively charged antibacterial drug, which is inhibited from initial burst release by physical confinement and realizes on-demand release in an acidified microenvironment of infection by electrostatic interaction; the blood compatibility surface layer is a linear polymer brush formed by a monofunctional hydrophilic monomer containing only one olefinic unsaturated bond, which forms a hydration barrier to resist protein passivation and platelet adhesion; both of them realize that the material has long-acting antibacterial, infection-responsive release and excellent blood compatibility based on synergistic effect, and is suitable for long-term indwelling vascular devices.

Description

Technical Field

[0001] This invention relates to the field of surface modification technology for medical devices, specifically to surface modification materials, their preparation methods, and applications. Background Technology

[0002] Peripherally inserted central venous catheters (PICCs) and central venous catheters (CVCs) are commonly used vascular access devices in clinical practice, widely used in chemotherapy, long-term intravenous infusions, and other therapeutic scenarios. Once inserted into a blood vessel as a foreign body, the surface of the catheter easily becomes a breeding ground for bacteria. After bacterial adhesion, the bacteria secrete extracellular polysaccharides to form a biofilm, which is a key factor in causing catheter-related bloodstream infections. Studies have shown that patients with catheters in place for more than two weeks have a significantly increased risk of infection, severely limiting the safe use and long-term placement of catheters.

[0003] To inhibit catheter-related infections, release-type antimicrobial surface modification technology loads antimicrobial agents onto the catheter surface or body, allowing for continuous release during use. This creates a localized antimicrobial environment, effectively killing bacteria and preventing biofilm formation. Current research has explored various types of antimicrobial agents: silver ions and nano-silver, guanidine salts (such as polyhexamethylene biguanide), antibiotics, chlorhexidine, and quaternary ammonium salts. These agents, introduced into catheters through bulk blending or surface coating, have all demonstrated good antimicrobial effects and have been successfully applied in industry. For example, Teleflex in the United States is a representative example, with its Arrow Gard... ® A series of central venous catheters (Registration Certificate No.: 20173032034) utilize the swelling properties of polyurethane substrates to load silver sulfadiazine and chlorhexidine, achieving sustained release of antibacterial components and effectively reducing catheter-related bloodstream infections. Domestically, Lepu Medical has developed a central venous catheter based on minocycline / rifampin sustained-release antibacterial technology (Registration Certificate No.: 20163031322), which continuously inhibits bacterial colonization through a surface coating of a composite antibacterial layer. Meanwhile, Meixin Medical has launched Anmicus. TM Ag silicone urinary catheters (original registration certificate number: Shanghai Food and Drug Administration Medical Device Approval No. 20142661258) employ a surface silver ion hydrophilic coating, achieving sterilization through the release of silver ions. The existence of the aforementioned commercialized products fully demonstrates the clinical value and market feasibility of the release-type antibacterial route.

[0004] However, existing release-type antibacterial technologies still have shortcomings in achieving long-lasting antibacterial effects. Most products rely on passive release strategies—antibacterial drugs passively diffuse or dissolve from the coating matrix based on a concentration gradient. These passive release systems generally suffer from the inherent defect of "initial burst release, insufficient later release": drugs on or near the coating surface dissolve rapidly upon initial contact with body fluids, forming an excessively high initial release peak, which may lead to local cytotoxicity; as the residence time increases, the release rate of the internal drug rapidly declines due to the increased diffusion path and decreased concentration gradient, failing to provide sufficient antibacterial protection in the later stages when the risk of infection is high. For example, patent CN101987223A stores antibacterial drugs in silicone rubber and releases them based on a concentration difference, while patent CN120837739A incorporates inorganic and organic antibacterial agents into a polymer substrate and releases them through diffusion; both are typical passive diffusion systems. Patent CN121428831A also introduces a pH-sensitive Schiff base crosslinking network as a "chemical lock," triggering a burst release of the drug from the outer layer in an acidic microenvironment. However, this approach still has the following limitations: First, the cross-linked network structure is destroyed after the Schiff base bonds break, making subsequent drug release unsustainable. Furthermore, the release of inner-layer silver ions depends on the swelling of the fiber core, which remains a passive release mechanism. Second, the coating surface is easily adhered to and deposited by components such as proteins and platelets in the blood, blocking drug release channels and causing drug passivation (i.e., ineffective release). Even if release is triggered, it is difficult for the drug to effectively diffuse to the interface. Therefore, there is still room for improvement in existing release-type antibacterial designs.

[0005] Therefore, how to achieve stable release of antibacterial drugs, on-demand release under infected conditions, and reduce the risks of the drug's service environment (such as blood protein component deposition blocking the release channel) to obtain long-lasting antibacterial effects are key technical problems that urgently need to be solved in this field. Summary of the Invention

[0006] In view of this, the technical problem to be solved by the present invention is to provide surface modified materials, their preparation methods and applications. The surface modified materials provided by the present invention have long-lasting antibacterial function and good blood compatibility, so as to solve the problems of uncontrollable release of antibacterial drugs, lack of responsiveness to the infection microenvironment, easy burst release in the early stage, insufficient antibacterial ability in the later stage, and the drug being easily passivated by the deposition of blood proteins, platelets and other components during service, thus making it difficult to maintain the antibacterial effect for a long time.

[0007] This invention provides a surface-modified material, comprising a substrate and an antibacterial underlayer and a blood-compatible surface layer disposed sequentially from the surface of the substrate outwards; The surface-modified material provided by this invention is a surface-modified material with a long-lasting antibacterial and blood-compatible bilayer structure. The antibacterial bottom layer is loaded with a positively charged antibacterial drug. The antibacterial bottom layer is a cross-linked polymer formed from multifunctional monomers; the multifunctional monomers simultaneously contain at least two olefinic unsaturated bonds and at least one carboxyl group, or the multifunctional monomers simultaneously contain at least two olefinic unsaturated bonds and at least one carboxyl group hydrolysis precursor. By using the above-mentioned multifunctional monomers to construct the cross-linked polymer, a cross-linked carboxyl polymer network can be formed on the substrate surface. This is beneficial in two ways: firstly, it helps to stably bind the antibacterial drug within the bottom framework through a physical confinement effect to suppress initial burst release; secondly, it helps to improve the loading capacity of the antibacterial drug by utilizing the electrostatic interaction between the carboxyl group and the positively charged antibacterial drug, and utilizes pH responsiveness to achieve on-demand release of the antibacterial drug in the acidified microenvironment caused by infection.

[0008] Furthermore, the multifunctional monomer of the present invention is selected from one or more of itaconic acid diacrylate, citrate triacrylate, or maleic acid diacrylate; wherein the structural formula of itaconic acid diacrylate is as follows: The structural formula of triacrylate citrate is: The structural formula of maleic acid diacrylate is: In some embodiments of the present invention, after polymerization of the multifunctional monomer, the ester bonds in its molecule can be hydrolyzed in a physiological environment to generate free carboxyl groups, forming a cross-linked network, and providing sites of action for binding positively charged antibacterial drugs within the cross-linked network.

[0009] The blood-compatible surface layer is a linear polymer formed from monofunctional hydrophilic monomers; each monofunctional hydrophilic monomer contains only one olefinic unsaturated bond and is hydrophilic. By further setting a linear polymer formed from monofunctional hydrophilic monomers on the surface of the antibacterial substrate, specifically by covalently linking a linear polymer brush to the surface of the antibacterial substrate, a hydrophilic surface layer with high chain segment freedom can be formed on the outer side of the antibacterial substrate. This hydrophilic surface layer, based on its high chain segment freedom, can fully extend on the surface of the antibacterial substrate, forming a dense hydration barrier. This reduces the adhesion and deposition of blood components such as proteins and platelets on the material surface, reduces the risk of drug release channels being blocked or drugs being passivated, thereby ensuring that the antibacterial drugs in the antibacterial substrate can be continuously and effectively released on demand in the infection microenvironment, while also endowing the material with certain anticoagulant properties.

[0010] Furthermore, the monofunctional hydrophilic monomer is selected from one or more of 2-methacryloyloxyethyl phosphorylcholine (MPC), acrylamide (AM), methacryloylethyl sulfobetaine (SBMA), and carboxybetaine methacrylate (CBMA), preferably MPC.

[0011] The positively charged antibacterial agent described in this invention is a positively charged cationic antibacterial agent. In some embodiments of this invention, the positively charged antibacterial agent is selected from one or more of chlorhexidine, pharmaceutically acceptable salts of chlorhexidine, polyhexamethylene biguanide, and quaternary ammonium cationic antibacterial agents. Further, the pharmaceutically acceptable salt of chlorhexidine is selected from one or more of chlorhexidine hydrochloride, chlorhexidine acetate, or chlorhexidine gluconate.

[0012] In some embodiments of the present invention, the loading of the positively charged antibacterial drug is 80 μg / cm³. 2 ~100μg / cm 2 The preferred value is 86 μg / cm³. 2 ~92.5 μg / cm 2 By incorporating a cross-linked network structure into the antibacterial substrate and introducing carboxyl groups, this invention can increase the loading capacity of positively charged antibacterial drugs in the antibacterial substrate and provide a drug reserve for subsequent long-acting release and infection microenvironment-responsive release.

[0013] The substrate described in this invention is a medical substrate suitable for long-term indwelling medical devices, such as substrates for vascular access devices like PICC and CVC. In some embodiments of this invention, the substrate is polyurethane, silicone rubber, or polyvinyl chloride.

[0014] The present invention also provides a method for preparing the above-mentioned surface-modified material, comprising the following steps: S1) The substrate adsorbed with oxidant is brought into contact with a solution containing multifunctional monomers and reducing agents and crosslinked to form an antibacterial underlayer on the surface of the substrate. S2) The substrate on which the antibacterial underlayer is formed is contacted with a solution containing a monofunctional hydrophilic monomer, hydrogen peroxide and a reducing agent and grafted polymerized to form a blood-compatible surface layer on the surface of the antibacterial underlayer. S3) The substrate having the antibacterial underlayer and the blood-compatible surface layer formed thereon is brought into contact with a solution of a positively charged antibacterial drug to obtain a surface-modified material.

[0015] The substrate with adsorbed oxidant described in this invention is obtained by contacting the substrate with an oxidant solution, causing the oxidant to adsorb onto the substrate surface. Preferably, the oxidant is selected from one or more of persulfate or hydrogen peroxide, more preferably ammonium persulfate. Preferably, the concentration of the oxidant is 0.005 mol / L to 0.05 mol / L, more preferably 0.01 mol / L to 0.02 mol / L. Preferably, the adsorption time is 5 min to 15 min.

[0016] In some embodiments of the present invention, a pretreatment of the substrate is further included before step S1). Specifically, the substrate may be ultrasonically cleaned with acetone, ethanol, and water in sequence, and then dried to obtain a pretreated substrate. The above pretreatment helps to remove impurities on the surface of the substrate and improves the stability of subsequent oxidant adsorption and surface polymerization reactions.

[0017] This invention first involves contacting a substrate adsorbed with an oxidant with a solution containing a multifunctional monomer and a reducing agent to undergo a crosslinking reaction, forming an antibacterial underlayer on the substrate surface. In some embodiments of this invention, the substrate adsorbed with an oxidant is immersed in a solution containing a multifunctional monomer and ascorbic acid, causing the multifunctional monomer to undergo a crosslinking reaction on the substrate surface, forming an antibacterial underlayer. The crosslinking reaction is conducted at room temperature, preferably 20-30°C, for 30-60 minutes. In a specific embodiment of this invention, the crosslinking reaction can be carried out in a constant-temperature shaker at a rotation speed of 80-120 rpm. After the reaction, the substrate can be dried, rinsed, and dried again to obtain a substrate with a crosslinked antibacterial underlayer.

[0018] The multifunctional monomer described in this invention is the same as described above and will not be repeated. Preferably, the concentration of the multifunctional monomer in the solution containing the multifunctional monomer and ascorbic acid is 5% w / v to 15% w / v, more preferably 5% w / v to 10% w / v. Preferably, the reducing agent is selected from one or more of ascorbic acid, sulfite, or ferrous salt, more preferably ascorbic acid. Preferably, the concentration of the reducing agent is 0.005 mol / L to 0.05 mol / L, more preferably 0.01 mol / L to 0.02 mol / L.

[0019] After forming an antibacterial underlayer on the surface of the substrate, the substrate with the antibacterial underlayer is contacted with a solution containing a monofunctional hydrophilic monomer, hydrogen peroxide, and a reducing agent, and graft polymerization is performed to form a blood-compatible surface layer on the surface of the antibacterial underlayer. In some embodiments of the present invention, the substrate with the antibacterial underlayer obtained in step S1) is immersed in a mixed solution containing a monofunctional hydrophilic monomer, hydrogen peroxide, and ascorbic acid, and graft polymerization is performed under graft polymerization conditions, so that the monofunctional hydrophilic monomer polymerizes on the surface of the antibacterial underlayer and is covalently linked to the surface of the antibacterial underlayer, forming a blood-compatible surface layer on the surface of the antibacterial underlayer. Preferably, the graft polymerization temperature is room temperature, preferably 20~30°C, and the reaction time of the graft polymerization is 5 min~15 min.

[0020] Further, the concentration of the monofunctional hydrophilic monomer in the solution containing the monofunctional hydrophilic monomer, hydrogen peroxide, and reducing agent is 0.1 mol / L to 1.0 mol / L, preferably 0.2 mol / L to 0.5 mol / L; the concentration of the hydrogen peroxide is 0.005 mol / L to 0.08 mol / L, preferably 0.01 mol / L to 0.06 mol / L; and the concentration of the reducing agent is 0.005 mol / L to 0.05 mol / L, preferably 0.01 mol / L to 0.02 mol / L. Preferably, the reducing agent is ascorbic acid.

[0021] Furthermore, the solution containing a monofunctional hydrophilic monomer, hydrogen peroxide, and a reducing agent described in this invention has a pH value of 7.0 to 7.4. In some embodiments of this invention, the solution containing the monofunctional hydrophilic monomer, hydrogen peroxide, and a reducing agent can be prepared using phosphate-buffered saline (PBS), and the pH value can be adjusted using PBS; after graft polymerization, the resulting substrate can be dried, rinsed, and dried again.

[0022] In this invention, after forming a blood-compatible surface layer on the surface of the antibacterial substrate, the substrate with the antibacterial substrate and the blood-compatible surface layer is brought into contact with a solution of a positively charged antibacterial drug to obtain a surface-modified material. In some embodiments of this invention, the substrate with the antibacterial substrate and the blood-compatible surface layer obtained in step S2) is immersed in a solution of a positively charged antibacterial drug, so that the positively charged antibacterial drug is loaded onto the antibacterial substrate through electrostatic interaction to obtain a surface-modified material.

[0023] Furthermore, the substrate having the antibacterial underlayer and the blood-compatible surface layer is contacted with a solution of positively charged antibacterial drug for 12 h to 48 h, more preferably 24 h to 48 h; the contact temperature is 25°C to 37°C. In some embodiments of the present invention, after the drug loading is completed, the material can be dried, rinsed, and dried again.

[0024] Furthermore, the concentration of the positively charged antibacterial drug in the solution of the positively charged antibacterial drug is 0.2% w / v to 3% w / v, preferably 0.5% w / v to 2% w / v; and the pH value of the solution of the positively charged antibacterial drug is 7.0 to 7.4.

[0025] The present invention also provides a medical device comprising any of the surface-modified materials described above. The medical device can be a long-term indwelling medical device, and more specifically, a vascular access device such as a PICC or CVC. Because the surface of the medical device includes the aforementioned antibacterial underlayer and blood-compatible surface layer, it is possible to simultaneously achieve antibacterial drug loading, stable release, infection microenvironment-responsive release, and anti-protein passivation on the surface of the medical device, which helps reduce the risk of bacterial adhesion, biofilm formation, and catheter-related infections during long-term indwelling.

[0026] This invention discloses surface-modified materials, their preparation methods, and applications. Compared with the prior art, this invention has at least the following beneficial effects: First, this invention constructs a cross-linked carboxyl-containing polymer network bottom layer, which utilizes the physical confinement effect of the network to suppress the initial burst release of drugs. At the same time, it increases the drug loading capacity by means of the electrostatic interaction between carboxyl groups and positively charged antibacterial drugs, thus laying the foundation for long-acting antibacterial effects.

[0027] Secondly, this invention utilizes the carboxyl groups on the antibacterial underlying network framework to form electrostatic reversible binding with positively charged antibacterial drugs. Under normal physiological conditions, the drugs are slowly released to maintain a basic antibacterial concentration. When bacterial infection leads to acidification of the local microenvironment, the degree of carboxyl group protonation increases, the electrostatic effect weakens, and the drugs are released on demand, realizing an intelligent antibacterial strategy from "stable prevention" to "infection triggering".

[0028] Third, this invention incorporates a linear blood-compatible surface layer formed by monofunctional hydrophilic monomers on the surface of the antibacterial substrate. This linear surface layer possesses high chain segment freedom, enabling it to form a hydrophilic barrier on the material surface. This reduces the adhesion and deposition of blood components such as proteins and platelets, minimizing the risk of drug release channel blockage and drug passivation, and improving the material's blood compatibility. The substrate achieves stable drug loading and on-demand release through cross-linking and electrostatic synergy, while the surface layer achieves anti-adhesion and anti-passivation through the high degree of freedom of its linear structure. The two layers are structurally complementary and functionally synergistic, jointly achieving long-lasting antibacterial effects.

[0029] Fourth, experimental results show that the surface-modified material obtained in the embodiments of the present invention has a high antibacterial drug loading capacity; under simulated infection micro-acidification environment, the antibacterial drug release rate is higher than that under normal physiological environment, indicating that it has the ability to release in response to infection microenvironment; after pre-incubation with bovine serum albumin (BSA), the release rate of the embodiments remains basically stable, indicating that the linear blood-compatible surface layer can reduce the influence of protein passivation on drug release; long-term release experiments show that the release curve of the embodiments is stable within 180 days, with no obvious initial burst release phenomenon; long-acting antibacterial experiments show that after 90 days and 180 days of pre-release in simulated in vivo protein environment, the embodiments can still maintain a high bactericidal rate against Staphylococcus aureus and Escherichia coli; blood compatibility experiments show that there is less platelet adhesion on the surface of the embodiments, indicating that the linear surface layer is beneficial to improving blood compatibility.

[0030] Fifth, comparative experiments show that when the antibacterial substrate uses a conventional multi-component cross-linked network, the antibacterial drug loading and on-demand release responsiveness decrease significantly due to the low carboxyl group density. When the blood-compatible surface layer uses a cross-linked hydrophilic network, the anti-protein passivation ability decreases significantly, and drug release after protein pre-incubation is significantly affected. This indicates that in this invention, the cross-linked antibacterial substrate formed by multifunctional monomers and the linear blood-compatible surface layer formed by monofunctional hydrophilic monomers must simultaneously satisfy their respective structural constraints. Only through their synergistic effect can high drug loading, responsive release, anti-protein passivation, and long-lasting antibacterial effects be achieved. Attached Figure Description

[0031] Figure 1 This is a schematic cross-sectional view of the surface-modified material described in this invention; Figure 2 A bar chart showing drug loading; Figure 3 Bar chart showing drug release on demand and anti-passivation performance; Figure 4 This is a long-acting drug release curve. Figure 5 Bar chart showing the bactericidal rate against Staphylococcus aureus after 90 and 180 days of pre-release in a simulated in vivo protein environment; Figure 6 Bar chart showing the bactericidal rate against Escherichia coli after 90 and 180 days of pre-release in a simulated in vivo protein environment; Figure 7 A bar chart showing platelet adhesion density. Detailed Implementation

[0032] This invention discloses surface-modified materials, their preparation methods, and applications. Those skilled in the art can refer to the content of this document and appropriately modify the process parameters to achieve the desired results. It should be particularly noted that all similar substitutions and modifications are obvious to those skilled in the art and are considered to be included in this invention. The methods and applications of this invention have been described through preferred embodiments, and those skilled in the art can clearly modify or appropriately change and combine the methods and applications described herein without departing from the content, spirit, and scope of this invention to realize and apply the technology of this invention.

[0033] The present invention forms a surface-modified bilayer structure on a substrate to obtain the surface-modified material, such as... Figure 1 As shown, Figure 1 This is a schematic cross-sectional view of the surface-modified material described in this invention, wherein 100 is the substrate, 200 is the antibacterial underlayer, 201 is the electrostatic interaction between ion pairs, 202 is the carboxylate group, 203 is chlorhexidine, 204 is the surface free radical initiation site, and 300 is the blood-compatible surface layer.

[0034] The antibacterial base layer 200 is a cross-linked, carboxyl-containing polymer network that can inhibit the initial burst release of drugs through physical confinement. The carboxyl groups (-COO) on the network backbone... - It can electrostatically adsorb cationic antibacterial agents to achieve high loading. The antibacterial bottom layer 200 has pH responsiveness and can trigger electrostatic weakening at different pH levels to achieve on-demand drug release.

[0035] 201 represents the electrostatic interaction between the carboxylate ion and chlorhexidine. The chemical formula of carboxylate ion 202 is -COO. - The chlorhexidine 203 is negatively charged. The surface free radical initiation site 204 is the initiation site for the blood-compatible surface layer, where the polymer brush grows.

[0036] Blood compatibility surface 300 is a linear polymer with the following characteristics or functions: ① high degree of freedom and dense hydration layer (anti-protein / platelet adhesion); ② prevents channel blockage and avoids drug release passivation; ③ ensures normal on-demand release.

[0037] Unless otherwise specified, all reagents used in this embodiment are commercially available and all experimental methods are conventional methods in the art. This embodiment uses polyurethane catheters as an example, but the present invention is also applicable to other medical catheter materials such as silicone rubber and polyvinyl chloride.

[0038] The present invention will be further described below with reference to the embodiments: Example 1 (1) Construction of antibacterial substrate The polyurethane substrate (2 cm × 2 cm) was ultrasonically cleaned sequentially with acetone, anhydrous ethanol, and deionized water for 15 minutes each. o Vacuum dry at 4°C for 4 hours for later use. Weigh 0.228 g of ammonium persulfate and dissolve it in 100 mL of deionized water to prepare a 0.01 mol / L oxidant solution. Immerse the pretreated substrate in the above solution at 20-30°C. o C. Let it stand for 10 minutes to absorb the liquid, then remove it and drain off any excess droplets from the surface.

[0039] Weigh 8.0 g of itaconic acid diacrylate and 0.352 g of ascorbic acid, dissolve them in 100 mL of deionized water to prepare an aqueous solution containing 8% w / v monomer and 0.02 mol / L reducing agent. Immediately immerse the peroxide-adsorbed substrate in the above monomer solution and place it at 20-30°C. o The reaction was carried out in a constant-temperature shaker at 100 rpm for 40 minutes at C. After the reaction was completed, it was removed and placed at 45°C. o Dry at C, then rinse three times with deionized water for five minutes each time, and then at 45°C. o C drying yields a cross-linked polyitacrylic acid substrate.

[0040] (2) Construction of blood compatibility surface

[0041] Weigh 8.85 g of 2-methacryloyloxyethylphosphorylcholine (MPC), 0.68 g of hydrogen peroxide (30% aqueous solution), and 0.352 g of ascorbic acid, and dissolve them in 100 mL of 0.01 mol / L phosphate buffer (PBS) to prepare a reaction solution containing 0.3 mol / L MPC, 0.06 mol / L H2O2, and 0.02 mol / L ascorbic acid. Adjust the pH to 7.4 with PBS. Immerse the above substrate in the above reaction solution and place it at 20-30°C. o The reaction was carried out in a constant-temperature shaker at 100 rpm for 8 minutes. After the reaction was completed, the mixture was removed and placed at 45°C. o Dry at C, then rinse three times with deionized water for five minutes each time, and then at 45°C. o After drying at C, a double-layer structure substrate with linear MPC brushes grafted onto its surface is obtained.

[0042] (3) Drug load

[0043] Weigh 1.0 g of chlorhexidine hydrochloride and dissolve it in 100 mL of 0.01 mol / L PBS (pH 7.4) to prepare a 1% w / v solution. Immerse the bilayer substrate obtained in step (2) in this solution and place it at 25-37°C. o The reaction was carried out in a constant-temperature shaker at 100 rpm for 24 hours at C. After the reaction was completed, the mixture was removed and stored at 45°C. oDry at C, then rinse three times with deionized water for five minutes each time, and then at 45°C. o Drying at C yields a drug-loaded double-layer modified material.

[0044] Example 2

[0045] It is basically the same as Example 1, except that in step (1), the monomer is replaced with 8g of triacrylate citrate, and other conditions are the same as in Example 1.

[0046] Example 3

[0047] It is basically the same as Example 1, except that in step (1), the monomer is replaced with 8g of maleic acid diacrylate, and other conditions are the same as in Example 1.

[0048] Example 4

[0049] The process is basically the same as in Example 1, except that in step (2), the MPC monomer is replaced with acrylamide (AM) of equal concentration (0.3 mol / L), and other conditions are the same as in Example 1. After polymerization, a linear polyacrylamide (PAM) brush is formed.

[0050] Comparative Example 1

[0051] The procedure is essentially the same as in Example 1, except that in step (1), the monomer is replaced with a mixture of 5.0 g of methacrylic acid (MAA), 3.0 g of hydroxyethyl methacrylate (HEMA), and 0.5 g of the crosslinking agent ethylene glycol dimethacrylate (EGDMA) (total concentration 8.5% w / v), and other conditions are the same as in Example 1. Steps (2) and (3) are exactly the same as in Example 1 (grafting MPC linear brush and loading chlorhexidine).

[0052] Comparative Example 2

[0053] The process is basically the same as in Example 1, except that in step (2), the MPC monomer is mixed with the crosslinking agent N,N'-methylenebisacrylamide (MBA) to prepare a reaction solution containing 0.3 mol / L MPC and 0.03 mol / L MBA. Other conditions are the same as in Example 1. After polymerization, a crosslinked polyMPC network (rather than a nonlinear brush) is formed.

[0054] Detection and Results

[0055] Test Example 1: Drug Loading Determination

[0056] The chlorhexidine hydrochloride loading in Examples 1-4, Comparative Example 1, and Comparative Example 2 was determined by ultraviolet spectrophotometry. First, a series of chlorhexidine hydrochloride standard solutions with concentrations (0, 5, 10, 20, 50, 100 μg / mL) were prepared, and the absorbance was measured at 258 nm to plot a standard curve. Each sample with a known surface area (2 cm × 2 cm) was completely immersed in 10 mL of pH 7.4 PBS and ultrasonically extracted for 30 minutes to ensure sufficient drug release. The absorbance of the extract was measured at 258 nm, and the drug concentration was calculated based on the standard curve. The drug loading (μg / cm²) was then determined using the formula: 2 The loading per unit area is calculated as follows: ) = (Drug concentration × Extract volume) / Sample surface area. The results are as follows: Figure 2 , Figure 2 The chart shows the drug loading rate. Examples 1-4 all exhibited high drug loading rates (86~92.5 μg / cm³). 2 The loading amount of Comparative Example 2 was comparable to that of Example 1, while the loading amount of Comparative Example 1 was significantly lower than that of all examples (only 41.3 μg / cm³). 2 This is because Comparative Example 1 uses a conventional multi-component network (polymerized acrylic acid and crosslinking agent), which has a low carboxyl group density, resulting in insufficient drug binding capacity.

[0057] Test Example 2: On-Demand Release and Anti-Protein Passivation Performance

[0058] Examples 1, 4, Comparative Example 1, and Comparative Example 2 were placed in PBS under three different conditions and incubated at 37°C for 24 hours. The cumulative release rate of chlorhexidine was then measured. The three conditions were: normal physiological environment (PBS at pH 7.4), slightly acidified infection environment (PBS at pH 6.5), and release under simulated protein conditions (pre-incubation for 24 hours in PBS at pH 7.4 containing 5% w / v bovine serum albumin, followed by rinsing and then incubation in PBS at pH 6.5 for 24 hours). The results are as follows: Figure 3 As shown, Figure 3The bar chart shows the drug's on-demand release and anti-passivation performance. Example 1 showed a significantly higher release rate (13.5%) at pH 6.5 than at pH 7.4 (6.0%), with a release ratio of approximately 2.25, indicating excellent on-demand release capability. Example 4 (PAM linear brush) showed a similar on-demand release capability to Example 1. Comparative Example 1 had a relatively high release rate (8.0%) at pH 7.4, but only increased to 9.5% at pH 6.5, with a release ratio of only about 1.2, indicating a weak on-demand release response, and its release rate remained consistently lower than that of Example 1. Comparative Example 2 showed a significantly higher release rate (13.0%) at pH 6.5 than at pH 7.4 (4.8%), similar to Example 1, demonstrating that its bottom layer also exhibited pH-responsive capability. Regarding resistance to protein passivation, the release rates of Examples 1 and 4 remained almost unchanged after BSA pre-incubation, indicating that their linear brush structure effectively resists protein adsorption. However, the release rate of Comparative Example 2 (crosslinked MPC network) decreased significantly after BSA pre-incubation, indicating that the crosslinked structure could not effectively resist protein passivation and completely lost its on-demand release capability. The release rate of Example 4 (PAM linear brush) decreased slightly after pre-incubation, but remained at a high level. The release rate of Comparative Example 1 also decreased after pre-incubation, which was due to the low density of carboxyl groups in the bottom layer causing premature leakage of some drugs.

[0059] Test Example 3: Long-acting drug release performance test

[0060] Samples from Examples 1, 4, and Comparative Example 1 were immersed in 10 mL of PBS at pH 7.4 for 37 minutes. o The solution was shaken at 100 rpm in a constant temperature shaker at C. All released solutions were collected at 1, 3, 7, 14, 21, 28, 45, 60, 90, 120, 150, and 180 days, and fresh PBS was added. The concentration of chlorhexidine hydrochloride was determined by UV spectrophotometry (λ=258 nm), and the cumulative release rate was calculated. Results are as follows: Figure 4 As shown, Figure 4 The drug release curves for Examples 1 and 4 are shown in the diagram. The release curves for Examples 1 and 4 are stable over 180 days, with no initial burst release and a cumulative release rate of approximately 50% over 180 days. Comparative Example 1, due to its low carboxyl group density and weak drug binding, experienced rapid dissolution in the initial release phase (a significantly higher release rate per day than Examples 1), and also had a lower total drug load, resulting in near-complete depletion of the drug by 180 days.

[0061] Test Example 4: Long-lasting antibacterial performance test

[0062] The plate count method was performed according to ISO 22196 standard. Staphylococcus aureus and Escherichia coli were cultured to the logarithmic development phase and diluted with PBS to approximately 1 × 10⁻⁶. 6CFU / mL. Samples from Examples 1, 4, Comparative Examples 1 and 2, and the uncoated sample were immersed in PBS containing 5% w / v BSA and pre-released at 37°C for 90 and 180 days (medium changed every 7 days) to simulate the long-term protein environment in vivo. After pre-release, the samples were gently rinsed with PBS, placed in 24-well plates, and 1 mL of bacterial culture was added. The plates were co-cultured at 37°C for 24 hours. The samples were then gently rinsed with PBS, and bacteria adhering to the sample surface were collected by sonication. After serial dilution, the samples were plated on LB agar plates and incubated at 37°C for 24 hours to count colonies. Simultaneously, the sample from Example 1 was pre-released in pure PBS for the same time as a control. The sterilization rate was calculated, and the results are as follows: Figure 5 As shown (Staphylococcus aureus) and Figure 6 As shown (E. coli), Figure 5 Bar charts showing the bactericidal rate against Staphylococcus aureus after 90 and 180 days of pre-release in a simulated in vivo protein environment. Figure 6 The bar chart shows the bactericidal rate against *E. coli* after 90 and 180 days of pre-release in a simulated in vivo protein environment. After 90 days of pre-release, Examples 1 and 4 maintained a bactericidal rate of over 95% against both bacteria, while Comparative Examples 1 and 2 had reduced their bactericidal rates to below 5%, almost completely losing their antibacterial ability. After 180 days of pre-release, Examples 1 and 4 still maintained excellent bactericidal ability, while the two comparative examples suffered from ineffective drug release due to low carboxyl group density at the bottom layer (Comparative Example 1) leading to premature drug depletion or poor surface anti-protein inactivation ability (Comparative Example 2), resulting in complete loss of long-term antibacterial performance. The bactericidal rate of Example 1 after pre-release in pure PBS was similar to that of the BSA-containing group, further demonstrating its anti-protein inactivation ability.

[0063] Test Example 5: Blood Compatibility Test

[0064] The test was conducted according to YY / T 1649.1-2019 standard. Fresh rabbit blood was mixed with 3.8% w / v sodium citrate at a ratio of 9:1, centrifuged at 1000 rpm for 10 minutes, and the supernatant platelet-rich plasma (PRP) was collected. Samples from Example 1, Example 4, Comparative Example 2, and the uncoated sample were then mixed with 0.5 mL of PRP at 37°C. o After incubation at C for 2 hours, the substrate was washed three times with physiological saline, fixed with 2.5% v / v glutaraldehyde for 2 hours, dehydrated with graded ethanol, and the substrate surface was observed using scanning electron microscopy. Platelet counts were performed in five random fields. Results are as follows: Figure 7 As shown, Figure 7 The bar chart shows platelet adhesion density. Platelets adhere extensively to the surface of the uncoated sample. Platelet adhesion is minimal on the surfaces of Examples 1 and 4, but significantly higher on the surface of Comparative Example 2, further illustrating that the linear brush structure is crucial for improving blood compatibility.

[0065] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.

Claims

1. A surface-modified material, characterized in that, It includes a substrate and an antibacterial underlayer and a blood-compatible surface layer disposed sequentially from the surface of the substrate outward; the antibacterial underlayer is loaded with a positively charged antibacterial drug; The antibacterial substrate is a cross-linked polymer formed from a multifunctional monomer; the multifunctional monomer contains at least two olefinic unsaturated bonds and at least one carboxyl group, or the multifunctional monomer contains at least two olefinic unsaturated bonds and at least one carboxyl group hydrolysis precursor. The blood-compatible surface layer is a linear polymer formed from a monofunctional hydrophilic monomer; the monofunctional hydrophilic monomer contains only one olefinic unsaturated bond.

2. The surface-modified material according to claim 1, characterized in that, The multifunctional monomer is selected from one or more of itaconic acid diacrylate, citrate triacrylate, or maleic acid diacrylate.

3. The surface-modified material according to claim 1, characterized in that, The monofunctional hydrophilic monomer is selected from one or more of 2-methacryloyloxyethyl phosphorylcholine, acrylamide, methacryloylethyl sulfobetaine, and carboxybetaine methacrylate.

4. The surface-modified material according to claim 1, characterized in that, The loading of the positively charged antibacterial drug is 80 μg / cm³. 2 ~100 μg / cm 2 .

5. The surface-modified material according to claim 1, characterized in that, The positively charged antibacterial agent is selected from one or more of chlorhexidine, pharmaceutically acceptable salts of chlorhexidine, polyhexamethylene biguanide, and quaternary ammonium cationic antibacterial agents.

6. The surface-modified material according to claim 5, characterized in that, The pharmaceutically acceptable salt of chlorhexidine is selected from one or more of chlorhexidine hydrochloride, chlorhexidine acetate, or chlorhexidine gluconate.

7. The surface-modified material according to claim 1, characterized in that, The substrate is polyurethane, silicone rubber, or polyvinyl chloride.

8. The method for preparing the surface-modified material according to any one of claims 1 to 7, characterized in that, Includes the following steps: S1) The substrate adsorbed with oxidant is brought into contact with a solution containing multifunctional monomers and reducing agents and crosslinked to form an antibacterial underlayer on the surface of the substrate. S2) The substrate on which the antibacterial underlayer is formed is contacted with a solution containing a monofunctional hydrophilic monomer, hydrogen peroxide and a reducing agent and grafted polymerized to form a blood-compatible surface layer on the surface of the antibacterial underlayer. S3) The substrate having the antibacterial underlayer and the blood-compatible surface layer formed thereon is brought into contact with a solution of a positively charged antibacterial drug to obtain a surface-modified material.

9. The preparation method according to claim 8, characterized in that, In step S1), the concentration of the multifunctional monomer in the solution containing the multifunctional monomer and the reducing agent is 5% w / v to 15% w / v; In step S2), the concentration of the monofunctional hydrophilic monomer in the solution containing the monofunctional hydrophilic monomer, hydrogen peroxide, and reducing agent is 0.1 mol / L to 1.0 mol / L. In step S3), the concentration of the positively charged antibacterial drug in the solution of the positively charged antibacterial drug is 0.2% w / v to 3% w / v.

10. A medical device, characterized in that, It includes the surface-modified material as described in any one of claims 1 to 7.

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