MXene and everolimus composite coating as well as preparation method and application thereof

Abstract

The invention discloses an MXene and everolimus composite coating and a preparation method and application thereof.The preparation method comprises the steps that MXene nanosheets and everolimus are compounded through hydrogen bonds and pi-pi stacking, the maximum drug loading capacity is 44.4%, and the MXene and everolimus composite coating is further blended with a degradable polymer to prepare the coating, the mass ratio of the MXene and everolimus compound to the degradable polymer is (1: 5)-(1: 15). An in-vitro experiment shows that the coating has a two-phase slow release characteristic, antioxidant activity and efficient antibacterial performance. A biological safety test shows that the hemolysis rate of a coating leaching solution is smaller than or equal to 4.1% + / -0.9%, the endothelial cell survival rate is 87.6% + / -3.8%, the problems of biotoxicity, process and infection of a traditional coating are solved from the source of materials, the coating is suitable for cardiovascular stent surface modification, and the risks of restenosis, oxidative stress and bacterial infection are jointly solved.

Description

Technical Field

[0001] The present invention relates to the technical field of biomedical materials, particularly to the surface coating of implantable medical devices, and more particularly to a composite coating material of two-dimensional transition metal carbides / nitrides (MXene) and everolimus, as well as its preparation method and application. Background Art

[0002] Cardiovascular diseases are one of the main causes of disability and death globally. Among them, the interventional treatment of coronary artery stenosis widely relies on drug-eluting stents. Drug-coated stents inhibit the excessive proliferation of smooth muscle cells by locally releasing anti-proliferative drugs (such as everolimus), thereby reducing the risk of vascular restenosis. Currently, the mainstream drug coatings use biodegradable polymers such as poly(lactic-co-glycolic acid) (PLGA) as carriers, but their hydrophobicity and acidic degradation products are prone to cause local inflammatory reactions. Existing coating materials still face multiple challenges: low drug loading efficiency, drug burst release, long-term inflammatory reactions, and lack of antibacterial and antioxidant functions, resulting in a significant increase in the risk of late in-stent thrombosis and infection.

[0003] In the prior art, CN106310371A discloses a tantalum copper coating (copper content 0% < Cu ≤ 10%, thickness 0.1 - 50 μm) prepared by plasma-enhanced chemical vapor deposition. Although it has antibacterial function, the direct release of its copper ions still results in relatively high cytotoxicity, and its preparation requires high-temperature hydrogen reduction, with complex processes and high copper deposition risks.

[0004] In order to solve the problems of biotoxicity, process, and infection of traditional coatings from the material root, it is necessary to develop a new generation of stent coatings with both high-efficiency treatment and biological safety. Summary of the Invention

[0005] The purpose of the present invention is to propose a composite coating of MXene and everolimus and its preparation method. Through the natural functional groups of MXene and non-covalent interactions, efficient drug loading and controlled release are achieved, and at the same time, antioxidant and conductive properties are imparted to the coating, solving the problems of drug burst release, inflammatory reactions, and delayed endothelial repair of traditional polymer coatings.

[0006] To achieve the above purpose, on the one hand, the present invention provides a preparation method for a composite coating of MXene and everolimus, including the following steps:

[0007] S1. Disperse MXene in an aqueous solution containing a surfactant, and perform ultrasonic treatment to form a uniform colloid;

[0008] S2. Dissolve everolimus in a water-miscible organic solvent, mix it with the MXene colloid, and stir and react in the dark for 12 - 48 h to form a MXene and everolimus complex;

[0009] S3, centrifugation to remove unadsorbed drugs, and drying to obtain MXene and everolimus complex powder;

[0010] S4. The MXene and everolimus complex is blended with a degradable polymer solution to form a coating on the surface of the medical device by a dip-coating method.

[0011] The mass ratio of the MXene and everolimus complex to the degradable polymer is 1:5 to 1:15, and the composite coating has a release conforming to a biphasic sustained-release characteristic.

[0012] Furthermore, the chemical formula of the MXene is Ti3C2T x , Tx is -OH and / or -F functional groups; the lateral size of the MXene nanosheet is 1-4.6 μm; and the MXene interlayer spacing is 1.05-1.32 nm.

[0013] Furthermore, in step S1, the surfactant is Pluronic F-127 with a concentration of 0.05-0.2 wt%; the concentration of the MXene colloid is 0.5-2.0 mg / mL, and the ultrasonic treatment time is 20-60 min.

[0014] Furthermore, in step S2, the organic solvent is tetrahydrofuran or dimethyl sulfoxide; and the mass feed ratio of MXene to everolimus is 1:0.25 to 1:2.

[0015] Furthermore, in step S3, the centrifugal speed is 12000 rpm, the centrifugal time is 20 min, and the drying condition is vacuum drying at 40-60° C. for 12-24 h.

[0016] Furthermore, in step S4, the degradable polymer is selected from at least one of poly(lactic-co-glycolic acid) (PLGA), poly(lactic acid) (PLA), and polycaprolactone (PCL). The concentration of the degradable polymer solution is 50-150 mg / mL, and the mass ratio of the added MXene@everolimus complex to PLGA is 1:5 to 1:15. The solvent is dichloromethane; the immersion-extraction speed is 5-15 mm / min, and the coating is repeated 3-5 times.

[0017] Furthermore, the everolimus loading amount in the MXene and everolimus composite is 8.3-44.4%.

[0018] On the other hand, the present invention provides a MXene and everolimus composite coating, the drug release of which conforms to a biphasic kinetic model: the 24-hour burst release is ≤30%, and the 30-day cumulative release is ≥80%.

[0019] Furthermore, the composite coating has an in vitro DPPH free radical scavenging IC50 The value is ≤36μg / mL; the 24h inhibition rate against Escherichia coli is ≥67.6%.

[0020] The present invention also provides an application of a MXene and everolimus composite coating in a medical device, characterized in that the medical device is coated with the composite coating, and the coating hemolysis rate is ≤4.1%±0.9%; and the endothelial cell survival rate is ≥87.6%±3.8%.

[0021] Furthermore, the medical device is a cardiovascular stent or a vascular catheter.

[0022] The beneficial effects of the present invention are:

[0023] 1. Efficient drug loading and controlled release: The high specific surface area and surface functional groups of MXene achieve efficient everolimus loading (8.3-44.4%) through hydrogen bonding and π-π stacking. Combined with biodegradable polymers, the release is regulated, with a 24-hour burst release of ≤30% and a 30-day cumulative release of ≥80%.

[0024] 2. Antioxidant properties: MXene and its transition metals (such as Ti 3+ / Ti 4+ )'s multivalent redox properties can scavenge reactive oxygen species (ROS) and inhibit oxidative stress. The coating scavenge IC 50 The value is 36μg / mL, reducing the risk of in-stent restenosis.

[0025] 3. Broad-spectrum antibacterial activity: The sharp edges and surface functional groups of MXene can physically destroy bacterial cell membranes (such as Staphylococcus aureus and Escherichia coli), with a colony count survival rate of 32.4% ± 3.1%, reducing the risk of infection in implanted devices.

[0026] The present invention introduces two-dimensional transition metal carbide (MXene) as a new drug carrier. MXene has both high specific surface area (200-400m 2 / g), controllable surface chemistry (-OH / -F functional groups), and intrinsic antioxidant properties. Its layered structure can efficiently load everolimus (up to 44.4%) through hydrogen bonding and π-π stacking, and synergizes with biodegradable polymers to achieve biphasic controlled release (over 80% sustained release over 30 days). MXene's conductivity can promote electrical signal conduction in endothelial cells, while its inert degradation (generating TiO2 nanoparticles) circumvents metal ion toxicity. The solution impregnation method (no high temperature required) is suitable for complex devices. The coated cell survival rate is ≥87.6%±3.8%, and the 24-hour antibacterial rate against Escherichia coli is ≥67.6%. It is suitable for cardiovascular stent surface modification to jointly address the risks of restenosis, oxidative stress, and bacterial infection. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The accompanying drawings are used to provide a further understanding of the present invention and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention and do not constitute a limitation of the present invention. In the accompanying drawings:

[0028] Figure 1 1 is the X-ray diffraction (XRD) pattern of MXene prepared according to Example 1 of the present invention.

[0029] Figure 2 is a scanning electron microscope (SEM) image of MXene prepared according to Example 1 of the present invention.

[0030] Figure 3 This is an infrared spectrum (FTIR) of the MXene prepared according to Example 1 of the present invention.

[0031] Figure 4 is the everolimus loading amount of the MXene@everolimus composite prepared according to Examples 3-8 of the present invention.

[0032] Figure 5 This is the in vitro release curve of the MXene@everolimus composite coating prepared according to Example 9 of the present invention.

[0033] Figure 6 is the DPPH radical scavenging rate of the MXene@everolimus composite coating prepared according to Example 7 of the present invention.

[0034] Figure 7 These are the antibacterial test results of the MXene@everolimus composite coating prepared according to Example 7 of the present invention (A is the normal saline control group for Staphylococcus aureus, B is the antibacterial effect diagram of the MXene@everolimus composite coating on Staphylococcus aureus, and C is the blank control group).

[0035] Figure 8 This is the hemolysis experimental data of the MXene@everolimus complex prepared according to Example 7 of the present invention.

[0036] Figure 9 This is a cytotoxicity test of the MXene@everolimus complex prepared according to Example 7 of the present invention. DETAILED DESCRIPTION

[0037] The present invention will now be described in further detail with reference to the accompanying drawings, but it should be understood that the protection scope of the present invention is not limited by the specific embodiments.

[0038] Example 1

[0039] This embodiment provides Ti3C2T x The preparation specifically comprises the following steps:

[0040] 1.MXene(Ti3C2T x ) preparation and characterization

[0041] 1g of lithium fluoride and 40mL of 9M hydrochloric acid were stirred in a polytetrafluoroethylene beaker for 30min to form a uniform etching system, and then 1g of Ti3AlC2 powder was slowly added and stirred at 40°C for 24h. After the reaction was completed, the reaction product was separated by centrifugation (3500rpm, 5min) and the supernatant was discarded. Then, the precipitate was repeatedly washed with deionized water until the pH of the supernatant was ≈6. The washed precipitate was dispersed in 200mL of deionized water, placed in an ice water bath and ultrasonically treated for 2h (power 300W, frequency 40kHz), and then centrifuged (3500rpm, 10min) to collect the upper dispersion, filter and vacuum dry to obtain Ti3C2T x .

[0042] Ti3C2T prepared in this example x XRD Figure 1 As shown in the figure, it was observed that the (002) crystal plane peak of the Ti3AlC2 MAX phase at 9.44° shifted to 6.06° after etching, indicating that the lattice spacing increased; at the same time, the strongest peak representing the Al crystal plane at 38.9° completely disappeared and there were no other residual peaks, indicating that the aluminum layer was successfully etched and formed a typical MXene layered structure, while eliminating the possibility of residual MAX phase and other impurities in the product.

[0043] Ti3C2T prepared in this example x SEM such as Figure 2 As shown, it can be seen that Ti3C2T x It presents a regular two-dimensional lamellar structure with a single-sheet lateral size of 1-4.6 μm, proving the successful preparation of MXene.

[0044] Ti3C2T prepared in this example x FTIR Figure 3 As shown, 3509 cm -1 The absorption peak at 1655 cm is attributed to the stretching vibration of -OH, and the absorption peak at 1655 cm -1 The peaks at , corresponding to the stretching vibration of C=O. The presence of these characteristic peaks is consistent with the previously reported Ti3C2T x The data are highly consistent, which strongly confirms that Ti3C2T x The successful synthesis and its surface is rich in expected functional groups.

[0045] Example 2

[0046] This example provides the preparation of a MXene / Pluronic F-127 dispersion, which specifically includes the following steps:

[0047] 100 mg of Pluronic F-127 was dissolved in 100 mL of deionized water and stirred magnetically until completely transparent to prepare a 0.1 wt% surfactant mother solution. x 20 mg of MXene was added to 10 mL of the above Pluronic F-127 solution to a final MXene concentration of 2.0 mg / mL. The mixture was placed in an ice-water bath and sonicated for 40 min.

[0048] Example 3

[0049] This embodiment provides a preparation of a MXene and everolimus complex, which specifically includes the following steps:

[0050] 1.0 mL of the MXene / Pluronic F-127 dispersion prepared in Example 2 was placed in a centrifuge tube. 10.0 mL of a 0.05 mg / mL tetrahydrofuran solution of everolimus was added to the dispersion, and the mixture was magnetically stirred in the dark under nitrogen for 24 hours. After the reaction, the unadsorbed drug was removed by centrifugation at 12,000 rpm for 20 minutes, and the supernatant was collected. The residual concentration of everolimus in the supernatant was determined by HPLC. The precipitate was washed three times with THF to completely remove free drug molecules, and the MXene and everolimus complex powder was obtained after vacuum drying.

[0051] Example 4

[0052] This example provides a preparation of a MXene and everolimus complex, which differs from Example 3 only in that the concentration of everolimus added is replaced by 0.075 mg / mL from 0.05 mg / mL. The preparation specifically includes the following steps:

[0053] 1.0 mL of the MXene / Pluronic F-127 dispersion prepared in Example 2 was placed in a centrifuge tube. 10.0 mL of a 0.075 mg / mL tetrahydrofuran solution of everolimus was added to the dispersion, and the mixture was magnetically stirred in the dark under nitrogen for 24 hours. After the reaction, the unadsorbed drug was removed by centrifugation at 12,000 rpm for 20 minutes, and the supernatant was collected. The residual everolimus concentration in the supernatant was determined by HPLC. The precipitate was washed three times with THF to completely remove free drug molecules, and a MXene and everolimus complex powder was obtained after vacuum drying.

[0054] Example 5

[0055] This example provides a preparation of a MXene and everolimus complex, which differs from Example 3 only in that the concentration of everolimus added is replaced by 0.1 mg / mL instead of 0.05 mg / mL. The preparation specifically includes the following steps:

[0056] 1.0 mL of the MXene / Pluronic F-127 dispersion prepared in Example 2 was placed in a centrifuge tube. 10.0 mL of a 0.1 mg / mL tetrahydrofuran solution of everolimus was added to the dispersion, and the mixture was magnetically stirred in the dark under nitrogen for 24 hours. After the reaction, the unadsorbed drug was removed by centrifugation at 12,000 rpm for 20 minutes, and the supernatant was collected. The residual everolimus concentration in the supernatant was determined by HPLC. The precipitate was washed three times with THF to completely remove free drug molecules, and a MXene and everolimus complex powder was obtained after vacuum drying.

[0057] Example 6

[0058] This example provides a preparation of a MXene and everolimus complex, which differs from Example 3 only in that the concentration of everolimus added is replaced by 0.2 mg / mL from 0.05 mg / mL. The preparation specifically includes the following steps:

[0059] 1.0 mL of the MXene / Pluronic F-127 dispersion prepared in Example 2 was placed in a centrifuge tube. 10.0 mL of a 0.2 mg / mL tetrahydrofuran solution of everolimus was added to the dispersion, and the mixture was magnetically stirred in the dark under nitrogen for 24 h. After the reaction, the unadsorbed drug was removed by centrifugation at 12,000 rpm for 20 min, and the supernatant was collected. The residual concentration of everolimus in the supernatant was determined by HPLC. The precipitate was washed three times with THF to completely remove free drug molecules, and a MXene and everolimus complex powder was obtained after vacuum drying.

[0060] Example 7

[0061] This example provides a preparation of a MXene and everolimus complex, which differs from Example 3 only in that the concentration of everolimus added is replaced by 0.3 mg / mL from 0.05 mg / mL. The preparation specifically includes the following steps:

[0062] 1.0 mL of the MXene / Pluronic F-127 dispersion prepared in Example 2 was placed in a centrifuge tube. 10.0 mL of a 0.3 mg / mL tetrahydrofuran solution of everolimus was added to the dispersion, and the mixture was magnetically stirred in the dark under nitrogen for 24 hours. After the reaction, the unadsorbed drug was removed by centrifugation at 12,000 rpm for 20 minutes, and the supernatant was collected. The residual concentration of everolimus in the supernatant was determined by HPLC. The precipitate was washed three times with THF to completely remove free drug molecules, and a MXene and everolimus complex powder was obtained after vacuum drying.

[0063] Example 8

[0064] This example provides a preparation of a MXene and everolimus complex, which differs from Example 3 only in that the concentration of everolimus added is replaced by 0.4 mg / mL from 0.05 mg / mL. The preparation specifically includes the following steps:

[0065] 1.0 mL of the MXene / Pluronic F-127 dispersion prepared in Example 2 was placed in a centrifuge tube. 10.0 mL of a 0.4 mg / mL tetrahydrofuran solution of everolimus was added to the dispersion, and the mixture was magnetically stirred in the dark under nitrogen for 24 hours. After the reaction, the unadsorbed drug was removed by centrifugation at 12,000 rpm for 20 minutes, and the supernatant was collected. The residual concentration of everolimus in the supernatant was determined by HPLC. The precipitate was washed three times with THF to completely remove free drug molecules, and the MXene and everolimus complex powder was obtained after vacuum drying.

[0066] like Figure 4 As shown, the drug loading capacity of the MXene@everolimus complex prepared in Examples 2-7 was determined as follows: the everolimus loading capacity of the MXene@everolimus complex was evaluated by measuring the residual everolimus concentration in the supernatant by HPLC. In the MXene@everolimus complexes prepared in Examples 3-8 with different mass ratios (everolimus:MXene / Pluronic F-127=0.5:2, 0.75:2, 1:2, 2:2, 3:2, 4:2), the drug loading capacity increased stepwise with increasing ratio, and the drug loading capacity was 8.3%, 20.6%, 25.5%, 39.4%, 44.4% and 44.4%, respectively (error range ±0.8-1.3%). When the mass ratio reached 3:2, drug loading peaked at 44.4%. The drug loading remained at 44.4% when the overdosage (4:2) was not statistically significant (p>0.05), indicating that the adsorption sites on the MXene surface were fully saturated. Based on these data, the optimal mass ratio of everolimus to MXene was selected as 3:2.

[0067] Example 9

[0068] This embodiment provides a method for preparing a MXene@everolimus composite coating, and the specific method is as follows:

[0069] A 10mg MXene@everolimus complex (everolimus:MXene mass ratio of 3:2) was mixed with poly(lactic-co-glycolic acid) (PLGA) at a mass ratio of 1:10 and dissolved in dichloromethane to create a coating solution with a solid content of 10wt%. The coating solution was evenly applied to the surface of a plasma-pretreated cobalt-chromium alloy stent using a dip-coating method (pulling speed of 10mm / min, repeated three times). After each coating, the target composite coating was dried at 60°C in a vacuum for 30 minutes to remove the solvent.

[0070] Example 10

[0071] This example provides a method for preparing a MXene@everolimus composite coating. The only difference from Example 9 is that the mass ratio of the added MXene@everolimus composite to PLGA is replaced from 1:10 to 1:5. The specific method is as follows:

[0072] A 10mg MXene@everolimus composite (everolimus:MXene mass ratio of 3:2) was mixed with poly(lactic-co-glycolic acid) at a mass ratio of 1:5 and dissolved in dichloromethane to create a coating solution with a solid content of 10wt%. The coating solution was evenly applied to the plasma-pretreated cobalt-chromium alloy stent surface using a dip-coating method (pulling speed of 10mm / min, repeated three times). After each coating, the target composite coating was dried at 60°C in a vacuum for 30 minutes to remove the solvent.

[0073] Example 11

[0074] This example provides a method for preparing a MXene@everolimus composite coating. The only difference from Example 9 is that the mass ratio of the added MXene@everolimus composite to PLGA is replaced from 1:10 to 1:15. The specific method is as follows:

[0075] A 10mg MXene@everolimus composite (everolimus:MXene mass ratio of 3:2) was mixed with poly(lactic-co-glycolic acid) at a mass ratio of 1:15 and dissolved in dichloromethane to create a coating solution with a solid content of 10wt%. The coating solution was evenly applied to the surface of a plasma-pretreated cobalt-chromium alloy stent using a dip-coating method (pulling speed of 10mm / min, repeated three times). After each coating, the target composite coating was dried at 60°C in a vacuum for 30 minutes to remove the solvent.

[0076] like Figure 5As shown, the in vitro release performance of the MXene@everolimus composite coating provided in Example 9 was evaluated as follows: the coated stent was immersed in phosphate buffered saline (PBS, pH 7.4, 37°C) containing 0.1% Tween 80, samples were taken at preset time points (0.5, 1, 2, 3, 5, 7, 14, 21, 28, and 30 days), and the everolimus concentration was quantitatively analyzed by high-performance liquid chromatography. The results showed that the coating exhibited a typical biphasic release profile: the initial burst release within 24 hours was 28% ± 2.1%, which may be mainly due to the rapid diffusion of the drug from the coating surface and loose areas; the release rate then slowed significantly, and the cumulative release reached 85% after 30 days. This stage may be regulated by the hydrolysis of the ester bond of PLGA and the diffusion between the MXene layers, indicating that the coating has a controlled sustained release capacity and can meet the long-term anti-proliferation needs of devices such as vascular stents.

[0077] The coating prepared in Example 10 had an initial burst release of 30% ± 1.2% within 24 hours, which may be mainly due to the lower PLGA addition ratio (complex: PLGA = 1:5), which resulted in a decrease in coating density and exposed more drugs to the near-surface area; the release rate then slowed down significantly, with the cumulative release reaching 85% in 25 days, indicating that the reduction in the amount of PLGA shortened the drug diffusion path and accelerated the formation of polymer degradation channels, thereby shortening the sustained-release period.

[0078] In contrast, the coating prepared in Example 11 had a burst release of 25% ± 1.8% within the initial 24 h, which may be mainly due to the higher PLGA addition ratio (complex: PLGA = 1:15) forming a dense matrix, which effectively reduced the surface exposure of the drug; the release rate then slowed down significantly, and the cumulative release amount reached 85% after 33 days, indicating that the increase in the amount of PLGA achieved an extension of the sustained-release period by extending the drug diffusion path rather than the degradation rate.

[0079] Therefore, in actual use, precise control can be achieved by adjusting the PLGA addition ratio according to clinical needs (such as burst release tolerance and treatment cycle): for devices with strict burst release control requirements (such as cardiovascular stents), a high PLGA ratio (1:15) is used to inhibit acute release (burst release ≤ 25%); for devices that need to reach therapeutic concentrations quickly (such as short-term implantable catheters), a low PLGA ratio (1:5) is used to shorten the release cycle (85% release in 25 days).

[0080] like Figure 6As shown, the antioxidant activity of the MXene@everolimus composite coating was evaluated by a DPPH free radical scavenging experiment: the MXene@everolimus coating powder prepared in Example 7 was dispersed in a mixed solution of anhydrous ethanol and deionized water in a mass ratio of 1:1 (concentration gradient: 0, 10, 20, 50, 100, 200 μg / mL, ultrasonic treatment for 10 min), mixed with DPPH ethanol solution (0.1 mM) in a volume ratio of 1:4, reacted at 25±0.5°C in the dark for 30 min, then centrifuged at 12000 rpm for 10 min to remove unreacted particles, and the supernatant was taken to measure the absorbance at 517 nm. The results showed that the DPPH free radical scavenging rate of the MXene@everolimus coating showed a super-nonlinear growth trend with increasing concentration. At 200 μg / mL, the scavenging rate exceeded 95%, and the DPPH free radical scavenging rate IC 50 The value was 36 μg / mL.

[0081] like Figure 7 As shown, the antibacterial performance of the MXene@everolimus composite coating provided in Example 7 was evaluated as follows: Escherichia coli (initial concentration 10 6 CFU / mL) and MXene@everolimus coating powder (200μg / mL) were co-incubated in LB medium at 37°C and pH 7.4 for 4 hours. The untreated bacterial solution was set as the negative control and the LB medium was set as the blank control. The 0-24h bacterial growth curve was dynamically monitored by spectrophotometry at a wavelength of 600nm, and the survival rate was quantified by the colony counting method (cultured at 37°C for 24h). The results showed that the OD600 value of the MXene@everolimus group dropped to 0.25±0.03 after 4h of incubation (negative control group 0.78±0.05, p<0.001), and the colony counting survival rate was 32.4%±3.1% (negative control group 100%, p<0.001), which met the anti-infection needs of vascular stents.

[0082] like Figure 8As shown, the hemolytic activity of the MXene@everolimus composite coating provided in Example 7 was evaluated: the anticoagulated whole blood of healthy rabbits (heparin sodium anticoagulation) was centrifuged at 3000rpm for 10min, the supernatant was discarded, and the red blood cell pellet was washed 3 times with normal saline, and finally prepared into a 2% (v / v) red blood cell suspension. 100μL of MXene@everolimus coating dispersions of different concentrations (0, 10, 50, 100, 150, 200μg / mL, normal saline as solvent) was mixed with 900μL of red blood cell suspension as the experimental group; the negative control group was 900μL of red blood cell suspension + 100μL of normal saline; the positive control group was 900μL of red blood cell suspension + 100μL of distilled water. All samples were incubated at 37°C for 60min, centrifuged at 3500rpm for 15min, and the supernatant was measured on an enzyme-linked microplate reader for absorbance at 544nm to calculate the hemolysis rate. As shown Figure 8 As shown in Figure 3, the hemolysis rate of the MXene@everolimus coating at 200 μg / mL was 4.1% ± 0.9% (n = 5), which was significantly lower than the 5% safety threshold.

[0083] like Figure 9 As shown, the cytotoxicity of the MXene@everolimus composite coating of Example 7 was evaluated by CCK-8 method: L929 cells (1×10 5 Cells were seeded into 96-well plates (10 cells / well). After the cells attached, the MXene@everolimus complex was diluted with DMEM to concentrations of 10, 20, 50, 100, and 200 μg / mL and added to each well. A blank control was also set up. After 24 hours of incubation, 10 μL of a 10% final concentration of CCK-8 solution was added. The cells were incubated in a 37°C incubator for 2 hours. The A value was then measured at a wavelength of 450 nm using a microplate reader to calculate the cell survival rate. The results showed that at 200 μg / mL, the cell survival rate was 87.6% ± 3.8%, meeting the cytotoxicity safety standard (survival rate ≥ 70%).

[0084] The above description is only a preferred specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any technician familiar with the technical field, within the technical scope disclosed by the present invention, who makes equivalent replacements or changes based on the technical solution and inventive concept of the present invention, should be covered by the scope of protection of the present invention.

Claims

1. A method for preparing a MXene and everolimus composite coating, characterized in that: The following steps are involved: S1, dispersing MXene in an aqueous solution containing a surfactant and ultrasonically treating it to form a uniform colloid; S2. Dissolve everolimus in a water-miscible organic solvent, mix with the MXene colloid, and react with stirring for 12-48 hours in the dark to form a MXene-everolimus complex; S3, centrifugation to remove unadsorbed drugs, and drying to obtain MXene and everolimus complex powder; S4. The MXene and everolimus complex is blended with a degradable polymer solution to form a coating on the surface of the medical device by a dip-coating method. The mass ratio of the MXene and everolimus complex to the degradable polymer is 1:5 to 1:15, and the composite coating has a release conforming to a biphasic sustained-release characteristic.

2. The method for preparing the MXene and everolimus composite coating according to claim 1, wherein: The chemical formula of the MXene is Ti3C2T x , T x The MXene nanosheets have a lateral size of 1-4.6 μm and a MXene interlayer spacing of 1.05-1.32 nm.

3. The method for preparing the MXene and everolimus composite coating according to claim 1, wherein: In step S1, the surfactant is Pluronic F-127 with a concentration of 0.05-0.2 wt%; the concentration of the MXene colloid is 0.5-2.0 mg / mL, and the ultrasonic treatment time is 20-60 min.

4. The method for preparing the MXene and everolimus composite coating according to claim 1, wherein: In step S2, the organic solvent is tetrahydrofuran or dimethyl sulfoxide; and the mass feed ratio of MXene to everolimus is 1:0.25 to 1:

2.

5. The method for preparing the MXene and everolimus composite coating according to claim 1, wherein: In step S3, the centrifugal speed is 12000 rpm, the centrifugal time is 20 min, and the drying condition is vacuum drying at 40-60° C. for 12-24 h.

6. The method for preparing the MXene and everolimus composite coating according to claim 1, wherein: In step S4, the degradable polymer is selected from at least one of poly(lactic-co-glycolic acid) (PLGA), poly(lactic acid) (PLA), and polycaprolactone (PCL). The concentration of the degradable polymer solution is 50-150 mg / mL, and the mass ratio of the added MXene@everolimus complex to PLGA is 1:5 to 1:

15. The solvent is dichloromethane; the immersion-extraction speed is 5-15 mm / min, and the coating is repeated 3-5 times.

7. The method for preparing the MXene and everolimus composite coating according to claim 1, wherein: The everolimus loading amount in the MXene and everolimus composite is 8.3-44.4%.

8. A MXene and everolimus composite coating prepared by the method according to any one of claims 1 to 7, characterized in that: The drug release conforms to the biphasic kinetic model: the burst release in 24 hours is ≤30%, and the cumulative release in 30 days is ≥80%.

9. The MXene and everolimus composite coating according to claim 8, characterized in that In vitro DPPH free radical scavenging IC of the composite coating 50 The value is 36μg / mL; the 24h inhibition rate against Escherichia coli is ≥67.6%.

10. Use of the MXene and everolimus composite coating according to claims 8-9 in medical devices, characterized in that: The medical device is coated with the composite coating, and the coating hemolysis rate is ≤4.1%±0.9%; and the endothelial cell survival rate is ≥87.6%±3.8%.

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