A PMPC nano-microsphere-based anticoagulant and antibacterial dialysis catheter coating and a preparation method thereof

Abstract

The application belongs to the field of medical materials and specifically relates to an anti-coagulation and anti-bacterial dialysis catheter coating based on PMPC nano microspheres and a preparation method thereof. The preparation method comprises the following steps: preparing PMPC nano microspheres, constructing a PDA / PEI coating, and then constructing a PDA / PEI / PMPC nano microsphere coating. The method has the advantages of easy availability of raw materials, simple process, and the prepared coating can simultaneously realize anti-coagulation and anti-bacterium, can significantly reduce protein adsorption and platelet adhesion, inhibit complement activation, reduce the risk of thrombosis and infection, and has good biocompatibility, and can solve the problems of single function, hidden safety hazards and the like of existing coatings, and is suitable for blood dialysis catheters and has high clinical application value.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of medical materials, and particularly relates to an anti-coagulation and anti-bacterial dialysis catheter coating based on poly(2-methacryloyloxyethyl phosphorylcholine) (PMPC) nanospheres and a preparation method thereof. BACKGROUND

[0002] Globally, the prevalence of kidney disease is increasing year by year. According to statistics, at present, 1 out of 10 people has chronic kidney disease, and 40-60% of chronic kidney disease patients can progress to end-stage renal disease in 5-20 years. Hemodialysis is the main treatment for end-stage renal disease. Dialysis catheters are the lifeline of hemodialysis patients. Catheter-related infection and thrombosis are the main factors affecting the service life of the catheter and the sufficiency of dialysis, and seriously affect the prognosis of patients.

[0003] Because the double-lumen catheter is in continuous contact with blood in the blood vessel, under low wall shear stress, platelets, the complement system and the coagulation system on the surface of the catheter can be activated (the activation of the complement system can also further promote the occurrence of coagulation), thereby causing thrombosis. On the other hand, due to the physicochemical properties of the material, the surface of the dialysis catheter is easy to cover various protein biomolecules, becoming an "anchor point" for bacterial adhesion, causing bacterial infection. In addition, catheter-related thrombosis and infection are a mutually promoting process. Therefore, the construction of an anti-coagulation and anti-bacterial functional coating on the surface of the catheter can effectively avoid thrombosis and reduce the risk of catheter-related infection.

[0004] In the field of blood purification, the construction of a functional anti-coagulation and anti-bacterial coating on the surface of the catheter is particularly insufficient in basic and applied research. At present, the coating of the dialysis catheter is mostly anti-coagulation or anti-bacterial, and a dialysis catheter with both anti-bacterial and anti-coagulation properties is still a market gap. In terms of anti-coagulation coating, previous research has focused on the catheter material itself, trying to improve the blood compatibility of the catheter material to reduce thrombotic events. Although there are numerous related studies, there are still few dialysis catheters that can reduce catheter-related infection and thrombosis events in clinical application. Although the commonly used heparin-coated dialysis catheter reduces platelet adhesion in vitro experiments, it has no anti-bacterial performance, and cannot significantly improve the service life of the dialysis catheter in clinical practice, nor can it effectively reduce the incidence of catheter-related thrombosis. In terms of anti-bacterial coating, some studies have constructed an extracellular polymeric substance matrix coating that destroys the biofilm to achieve antibiotic penetration and sterilization, but this may increase the risk of bacterial drug resistance; some studies have constructed a coating of metal ions such as copper, zinc and silver to destroy the bacterial cell membrane and cause cytoplasmic protein denaturation to kill bacteria, but the realization of the anti-bacterial effect also increases cytotoxicity. Therefore, preventing the adhesion and colonization of microorganisms in the local area of the biomaterial in the early stage of microbial membrane formation may be a more effective and safe anti-bacterial means.

[0005] Therefore, based on this, the technical solution of the present invention is proposed. Summary of the Invention

[0006] To address the problems existing in the prior art, the present invention provides an anticoagulant and antibacterial dialysis catheter coating based on PMPC nanospheres and its preparation method, which can specifically solve the problems of single function, limited clinical application effect, and safety hazards of existing dialysis catheter coatings, and has both excellent anticoagulant and antibacterial properties and good practicality.

[0007] This invention provides a method for preparing an anticoagulant and antibacterial coating for dialysis catheters based on PMPC nanospheres, the method comprising the following steps:

[0008] (I) Preparation of PMPC nanospheres:

[0009] (I-1) Dissolve 2-methacryloyloxyethylphosphorylcholine (MPC) and a crosslinking agent in a solvent to obtain a premix;

[0010] (I-2) Inert gas is introduced into the premixed liquid to remove oxygen and an initiator is added, and then the reaction is heated to obtain a reaction solution;

[0011] (I-3) Centrifuge the reaction solution to collect the precipitate, and wash and dry it in sequence to obtain PMPC nanospheres;

[0012] (II) Construction of polydopamine / polyethyleneimine (PDA / PEI) coating:

[0013] (II-1) Dissolve dopamine and polyethyleneimine in a solvent to obtain a mixed solution;

[0014] (II-2) Immerse the dialysis catheter in the mixed solution and shake it. After cleaning, the dialysis catheter with PDA / PEI coating is obtained.

[0015] (III) Construction of PDA / PEI / PMPC nanosphere coating:

[0016] (III-1) Dissolve PMPC nanospheres in a solvent to obtain a PMPC nanosphere solution;

[0017] (III-2) Immerse the dialysis catheter containing the PDA / PEI coating into the PMPC nanosphere solution. After the immersion, the PDA / PEI / PMPC nanosphere coating is completed, and the anticoagulant and antibacterial dialysis catheter coating based on PMPC nanospheres is obtained.

[0018] Preferably, in step (I-1):

[0019] The crosslinking agent is N,N-methylenebisacrylamide or N,N-bis(acryloyl)cysteine;

[0020] And / or, the solvent is acetonitrile;

[0021] And / or, the molar ratio of the MPC to the crosslinking agent is 7.5-8.5:1.

[0022] Preferably, in step (I-2):

[0023] The inert gas is nitrogen or argon;

[0024] And / or, the initiator is azobisisobutyronitrile, potassium persulfate, or dimethyl-2,2'-azobis(2-methylpropionate).

[0025] And / or, the heating reaction is carried out at a temperature of 90-95°C for 1-2 hours and at a stirring rate of 200-250 r / min.

[0026] Preferably, in step (I-3):

[0027] The centrifugation rate is 12000-15000 r / min, and the time is 15-20 min;

[0028] And / or, the drying method is freeze-drying for 24-28 hours.

[0029] Preferably, in step (II-1):

[0030] The solvent is Tris-HCl buffer solution, pH=8.5;

[0031] And / or, in the mixed solution, the concentration of dopamine is 2 mg / mL and the concentration of polyethyleneimine is 0.5-1 mg / mL.

[0032] Preferably, in step (II-2), the oscillation treatment time is 12-14 hours.

[0033] Preferably, in step (III-1):

[0034] The solvent is a Tris-HCl buffer solution with pH=8.5;

[0035] And / or, the concentration of PMPC nanospheres in the PMPC nanosphere solution is 2-3 mg / mL.

[0036] Preferably, in step (III-2), the immersion time is 24-28 hours.

[0037] Based on the same technical concept, another aspect of the present invention is to provide an anticoagulant and antibacterial dialysis catheter coating based on PMPC nanospheres obtained by the above preparation method.

[0038] The beneficial effects of this invention are as follows:

[0039] The raw materials used in this invention are readily available and inexpensive, and the preparation process is simple and feasible. The precipitation polymerization method for preparing PMPC nanospheres is more portable and feasible, with simple reaction conditions (no surfactants or stabilizers required, high product purity, obtainable through simple high-speed centrifugation), and a short reaction time (as short as one hour). Furthermore, it can form uniformly sized spherical particles. The prepared PDA / PEI / PMPC nanosphere-coated dialysis catheter exhibits significant antibacterial adhesion function compared to uncoated commercially available dialysis catheters, and can significantly reduce protein adhesion, platelet adhesion and activation, as well as complement activation, thus reducing the risk of thrombosis. Specifically:

[0040] 1. Addressing the issue of single-function protection and achieving dual protection: Addressing the current situation where most dialysis catheter coatings are merely anticoagulant or antibacterial, this invention combines PMPC nanospheres with a PDA / PEI coating. PMPC nanospheres possess highly efficient anticoagulant and antibacterial adhesion functions, while PEI itself has antibacterial properties. The synergistic effect of these two components gives the coating both anticoagulant and antibacterial properties, filling the market gap for dialysis catheter products with both functions. This effectively prevents catheter-related thrombosis and infection, improving patient prognosis.

[0041] 2. Enhanced anticoagulation effect and guaranteed clinical application value: Compared with existing heparin-coated dialysis catheters, which cannot significantly prolong catheter life and reduce thrombotic events in clinical practice, the coating of this invention can enhance the anticoagulation effect through multiple mechanisms. PMPC nanospheres can reduce protein adhesion, platelet adhesion and activation, and also inhibit complement activation, thereby reducing the risk of thrombosis from the source; at the same time, PEI can improve the stability of the PDA-mediated layer, ensuring the sustained performance of the overall anticoagulation function of the coating and enhancing the clinical application value of the catheter.

[0042] 3. Avoiding safety hazards and enhancing biocompatibility: Addressing the issue of antibacterial coatings potentially leading to bacterial resistance or cytotoxicity, this invention utilizes PMPC nanospheres to prevent microbial adhesion and colonization in the early stages of microbial membrane formation. This eliminates the need for antibiotic penetration or metal ions to disrupt bacterial structure, fundamentally avoiding the risks of bacterial resistance and cytotoxicity. Furthermore, testing shows that the coating's hemolysis rate is far below the 5% requirement for medical devices in China, exhibiting excellent anti-protein adhesion properties and good biocompatibility, making it safer to use.

[0043] 4. Simplified preparation process and reduced application cost: This invention uses precipitation polymerization to prepare PMPC nanospheres, which does not require surfactants and stabilizers. The reaction conditions are simple (only temperature control of 90-95℃ and stirring rate of 200-250r / min are required), and the reaction time can be as short as 1 hour. High-purity products can be obtained by high-speed centrifugation. Moreover, the raw materials used are readily available and inexpensive, and the overall preparation process is simple and feasible, which is conducive to large-scale production. It can effectively reduce the preparation and application cost of catheter coatings and facilitate clinical promotion. Attached Figure Description

[0044] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 This is a SEM image of PMPC nanospheres in a dry state.

[0046] Figure 2 Infrared spectral analysis of monomer MPC, crosslinking agent MBA, and PMPC nanospheres (A: monomer MPC; B: crosslinking agent MBA; C: PMPC nanospheres).

[0047] Figure 3 These are scanning electron microscope (SEM) images of PDA, PDA / PEI, and PDA / PEI / PMPC nanosphere coatings.

[0048] Figure 4 The graph shows the water contact angle (a), hemolysis rate (b), adsorption amount of bovine serum albumin (BDA) and fibrinogen (Fbg) of the PDA / PEI / PMPC nanosphere coating, and the percentage decrease in adsorption amount of BSA (e) and Fbg (f) compared to the blank catheter.

[0049] Figure 5 These are SEM images showing the adhesion of each coating to platelets.

[0050] Figure 6 This is a graph showing the number of platelets adhering to each coating surface and the percentage decrease in platelet adhesion (relative to the blank PU catheter).

[0051] Figure 7 This section shows the effect of PDA / PEI / PMPC nanosphere coatings on complement activation. The graphs show the C3a(a) and C5a(b) content in plasma in contact with the blank catheter and each coating. The graphs also show the percentage decrease in C3a(c) and C5a(d) content in plasma in contact with each coating compared to the blank catheter.

[0052] Figure 8 This is a scanning electron microscope image showing the adhesion of E. coli to blank catheters and PDA / PEI / PMPC nanosphere coatings.

[0053] Figure 9 This is a scanning electron microscope image showing the adhesion of Staphylococcus aureus to blank catheters and PDA / PEI / PMPC nanosphere coatings. Detailed Implementation

[0054] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be described in detail below. Obviously, the described embodiments are merely some embodiments of this invention, and not all embodiments. Based on the embodiments of this invention, all other implementation methods obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0055] Example 1

[0056] This embodiment provides a method for preparing an anticoagulant and antibacterial dialysis catheter coating based on PMPC nanospheres. The preparation method includes the following steps:

[0057] (I) Preparation of PMPC nanospheres:

[0058] Add 300 mg of MPC (0.025 mol / L) and 21 mg of crosslinking agent N,N-methylenebisacrylamide (MBA) (molar ratio MPC:MBA = 7.5:1) to a 100 mL flask containing 40 mL of acetonitrile, and sonicate to dissolve completely.

[0059] After purging the above solution with nitrogen to remove oxygen, 4 mg of the initiator azobisisobutyronitrile (AIBN) was immediately added, and the solution was sealed. The mixed solution was stirred (200 r / min) in an oil bath at 90 °C for 1 h, and then immediately cooled to room temperature. The resulting milky white solution was centrifuged at high speed (12000 r / min, 15 min), and the white precipitate was washed three times with deionized water. The washed precipitate was then freeze-dried for 24 h to obtain a white solid, which was the PMPC nanospheres.

[0060] Furthermore, scanning electron microscopy (SEM) and infrared characterization were performed, specifically:

[0061] SEM revealed that the PMPC nanospheres were uniformly sized spherical structures with a diameter of approximately 700 nm (e.g., ...). Figure 1 (As shown).

[0062] Infrared spectroscopy suggests that the crosslinking agents MBA and PMPC nanospheres are at 1536 cm⁻¹ -1and 1658cm -1 The appearance of two identical absorption peaks at this location is attributed to the typical amide I and II bands (-CONHR) of MBA, indicating that the crosslinking agent MBA was successfully introduced into the PMPC nanospheres, and also suggesting the successful preparation of PMPC nanospheres (e.g., Figure 2 (As shown).

[0063] (II) Construction of PDA / PEI coating:

[0064] The medical hemodialysis catheter (made of polyurethane) was treated with a mixed solution of dopamine (2 mg / mL) and PEI (1 mg / mL) (in Tris-HCl buffer, 10 mM, pH=8.5) with shaking for 12 h. After treatment, it was rinsed with deionized water and ready for use.

[0065] After the PDA / PEI / PMPC nanosphere coating was constructed, more detailed characterization was performed, specifically:

[0066] Depend on Figure 3 It can be seen that the introduction of PEI reduces the aggregated growth of PDA particles. PMPC nanospheres can spread relatively evenly on the polyurethane surface in a uniform spherical structure with no obvious agglomeration, nor any obvious shrinkage or collapse.

[0067] Untreated and uncoated hemodialysis catheters have no antibacterial properties and also lack anticoagulant properties. The PDA / PEI / PMPC nanosphere coating constructed on the surface of the dialysis catheter aims to improve the performance of the original dialysis catheter and has excellent anticoagulant and antibacterial effects.

[0068] like Figure 4 As shown in Figure a, after constructing a PDA / PEI / PMPC nanosphere coating on the surface of the conduit, the material surface exhibits superhydrophilic properties (water contact angle less than 10°). Figure 4 As shown in b, in the hemolysis rate test, whether using the direct contact method or the 72-hour extraction method, the hemolysis rate was far below the national requirement of 5% for medical devices, both being <1%. Figure 4 As shown in c and d, the PDA / PEI / PMPC nanosphere coating exhibits excellent anti-adsorption properties against both albumin and fibrinogen. Figure 4 As shown in e and f, compared to uncoated catheters, the PDA / PEI / PMPC nanosphere coated catheters exhibit a reduction of over 90% in the adsorption of albumin and fibrinogen. This lower hemolysis rate and highly efficient anti-protein adhesion properties indicate that the coated catheters of this invention possess excellent biocompatibility.

[0069] PDA / PEI / PMPC nanosphere coatings also exhibit excellent effects in resisting platelet adhesion. For example...Figure 5 As shown, when the concentration of PMPC nanospheres was 1 mg / mL, the coating effect was poor, and no platelet adhesion was observed in the area coated with PMPC nanospheres (while a large number of platelets were observed in the area where PMPC nanospheres were not coated). When the concentration of PMPC nanospheres was increased to 2 mg / mL, the coating effect was better, and no obvious platelet adhesion was observed on the entire coating surface.

[0070] like Figure 6 As shown, the introduction of the PDA / PEI / PMPC nanosphere coating reduces the number of platelets adhering to the surface of the dialysis catheter by more than 95%. Platelet adhesion is an initiating factor for thrombosis, and our coated catheter has a strong anti-platelet adhesion function, achieving excellent anticoagulant performance.

[0071] like Figure 7 As shown in a and b, the PDA / PEI / PMPC nanosphere coating also exhibits good inhibitory effects on the activation of complement C3a and C5a. Compared to the blank duct, such as Figure 7 As shown in c and d, the coated catheter inhibits the activation of complement C3a and C5a by more than 80%. Complement C3a and C5a can activate the coagulation system, and the high efficiency of the coated catheter of this invention in inhibiting complement C3a and C5a contributes to achieving better anticoagulation effects.

[0072] PDA / PEI / PMPC nanosphere-coated dialysis catheters were used with bacterial solutions (1×10⁻⁶) at levels far exceeding those commonly seen in clinical bacteremia. 6 CFU / mL Escherichia coli, 1×10 6 After co-incubation with CFU / mL Staphylococcus aureus for 12 h, the coating was washed several times with PBS, and then fixed and dehydrated in a gradient manner. Figure 8 and Figure 9 As shown, SEM revealed a large number of bacteria adhering to the surface of the uncoated dialysis catheter; while almost no bacteria were observed adhering to the surface of the PDA / PEI / PMPC nanosphere-coated dialysis catheter (PMPC nanospheres at 2 mg / mL). When the PMPC nanosphere concentration was 1 mg / mL, SEM showed no bacterial adhesion in the PMPC nanosphere-coated area, further suggesting that the PMPC nanosphere-coated dialysis catheter has strong anti-adhesion properties against bacteria.

[0073] The experimental data above all indicate that the PDA / PEI / PMPC nanosphere coated dialysis catheter exhibits superior anticoagulation and antibacterial capabilities compared to uncoated dialysis catheters on the market.

[0074] Example 2

[0075] The preparation method of Example 2 is basically the same as that of Example 1, with the only difference being the selection of raw materials, specifically:

[0076] The crosslinking agent was N,N-bis(acryloyl)cysteamine, the inert gas was argon, and the initiator was potassium persulfate.

[0077] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for preparing an anticoagulant and antibacterial dialysis catheter coating based on PMPC nanospheres, characterized in that, The preparation method includes the following steps: (I) Preparation of PMPC nanospheres: (I-1) Dissolve MPC and crosslinking agent in solvent to obtain premix; (I-2) Inert gas is introduced into the premixed liquid to remove oxygen and an initiator is added, and then the reaction is heated to obtain a reaction solution; (I-3) Centrifuge the reaction solution to collect the precipitate, and wash and dry it in sequence to obtain PMPC nanospheres; (II) Construction of PDA / PEI coating: (II-1) Dissolve dopamine and polyethyleneimine in a solvent to obtain a mixed solution; (II-2) Immerse the dialysis catheter in the mixed solution and shake it. After cleaning, the dialysis catheter with PDA / PEI coating is obtained. (III) Construction of PDA / PEI / PMPC nanosphere coating: (III-1) Dissolve PMPC nanospheres in a solvent to obtain a PMPC nanosphere solution; (III-2) Immerse the dialysis catheter containing the PDA / PEI coating into the PMPC nanosphere solution. After the immersion, the PDA / PEI / PMPC nanosphere coating is completed, and the anticoagulant and antibacterial dialysis catheter coating based on PMPC nanospheres is obtained.

2. The method for preparing the anticoagulant and antibacterial dialysis catheter coating based on PMPC nanospheres according to claim 1, characterized in that, In step (I-1): The crosslinking agent is N,N-methylenebisacrylamide or N,N-bis(acryloyl)cysteine; And / or, the solvent is acetonitrile; And / or, the molar ratio of the MPC to the crosslinking agent is 7.5-8.5:

1.

3. The method for preparing the anticoagulant and antibacterial dialysis catheter coating based on PMPC nanospheres according to claim 1, characterized in that, In step (I-2): The inert gas is nitrogen or argon; And / or, the initiator is azobisisobutyronitrile, potassium persulfate, or dimethyl-2,2'-azobis(2-methylpropionate). And / or, the heating reaction is carried out at a temperature of 90-95°C for 1-2 hours and at a stirring rate of 200-250 r / min.

4. The method for preparing the anticoagulation and antibacterial dialysis catheter coating based on PMPC nanospheres according to claim 1, characterized in that, In step (I-3): The centrifugation rate is 12000-15000 r / min, and the time is 15-20 min; And / or, the drying method is freeze-drying for 24-28 hours.

5. The method for preparing the anticoagulant and antibacterial dialysis catheter coating based on PMPC nanospheres according to claim 1, characterized in that, In step (II-1): The solvent is a Tris-HCl buffer solution with pH=8.5; And / or, in the mixed solution, the concentration of dopamine is 2 mg / mL and the concentration of polyethyleneimine is 0.5-1 mg / mL.

6. The method for preparing the anticoagulant and antibacterial dialysis catheter coating based on PMPC nanospheres according to claim 1, characterized in that, In step (II-2), the oscillation process takes 12-14 hours.

7. The method for preparing the anticoagulation and antibacterial dialysis catheter coating based on PMPC nanospheres according to claim 1, characterized in that, In step (III-1): The solvent is a Tris-HCl buffer solution with pH=8.5; And / or, the concentration of PMPC nanospheres in the PMPC nanosphere solution is 2-3 mg / mL.

8. The method for preparing the anticoagulation and antibacterial dialysis catheter coating based on PMPC nanospheres according to claim 1, characterized in that, In step (III-2), the immersion time is 24-28 hours.

9. The anticoagulant and antibacterial dialysis catheter coating based on PMPC nanospheres obtained by the preparation method according to any one of claims 1-8.

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