A medical polymer, its preparation method and application

Abstract

This invention provides a medical polymer and its preparation method. The medical polymer includes sodium alginate segments grafted with polyethylene glycol segments. The polyethylene glycol segments can be end-functionalized polyethylene glycol, and the ends of the polyethylene glycol segments are grafted with selenocysteine ​​or L-selenocysteine. The medical polymer provided by this invention exhibits excellent anticoagulant properties and endothelial cell proliferation-promoting properties, and can be applied to the surface coating of artificial blood vessels and medical devices.

Description

Technical Field

[0001] This invention relates to the field of medical biomaterials and medical devices, and in particular to a medical polymer, its preparation method, and its applications. Background Technology

[0002] Cardiovascular disease has become one of the leading causes of morbidity and mortality worldwide, making its treatment a major public health issue. For completely occluded vascular lesions, bypass surgery is typically performed using autologous or artificial blood vessels to restore blood flow. However, the availability of autologous blood vessels is limited and can cause further trauma; therefore, using artificial blood vessels for bypass surgery has become a crucial alternative treatment method in clinical practice. However, due to insufficient biocompatibility in the fabrication of artificial blood vessel materials, significant challenges remain in the development of small-diameter artificial blood vessels (less than 3 mm in diameter). Developing new polymeric materials with excellent biocompatibility for the fabrication of small-diameter artificial blood vessels is of great value. On the other hand, for incompletely occluded stenotic cardiovascular diseases, stent implantation / interventional therapy has become a widely used clinical method. However, whether it is a drug-eluting stent prepared using a metallic stent platform or a biodegradable drug-eluting stent prepared using biodegradable polymeric materials, problems such as thrombosis, intimal hyperplasia, and late-stage thrombosis still exist in practical clinical applications. The main reason is that the current polymer carrier materials for drug-eluting coatings and metal stent platforms have insufficient biocompatibility, which can easily trigger coagulation and inflammatory reactions, leading to coagulation or restenosis. At the same time, the anti-proliferative drugs (such as paclitaxel and rapamycin) released by the drug-eluting coatings inhibit the growth of endothelial cells while inhibiting the proliferation of smooth muscle cells, thereby delaying the healing of the vascular endothelium and causing long-term clinical complications such as late thrombosis and late restenosis.

[0003] Polysaccharide polymers (such as sodium alginate, hyaluronic acid, and chitosan) are a class of natural polysaccharides with good biological activity. They have great potential applications in biomaterials, tissue engineering, and implantable / interventional medical devices, and have been widely studied and applied. However, for blood-contact materials or implantable / interventional vascular medical devices (such as small-diameter artificial blood vessels and vascular stents), the biological functions of natural polysaccharides are insufficient. For example, sodium alginate has certain anticoagulant properties, but it cannot induce the repair and regeneration of natural vascular endothelium, thus failing to meet the needs of medical biomaterials. Summary of the Invention

[0004] The first objective of this invention is to provide a polyethylene glycol-modified sodium alginate; the second objective is to provide a medical polymer that catalyzes the release of NO; ​​the third objective is to provide a method for preparing the polyethylene glycol-modified sodium alginate and the medical polymer that catalyzes the release of NO; ​​and the fourth objective is to provide the application of the medical polymer that catalyzes the release of NO in the preparation of small-diameter artificial blood vessels, as well as blood contact materials and device surface coatings. The specific technical solutions of this invention are as follows.

[0005] Technical solution: The present invention provides a medical polymer having the structural formula shown in formula (1).

[0006]

[0007] In formula (1), ~~~ represents sodium alginate segments, X represents the linking structure, and Y represents amino, carboxyl, hydroxyl groups, or the structure shown in formula (2).

[0008]

[0009] In equation (2), Z is the connecting structure and R is a carboxyl group or a hydrogen atom.

[0010] Optionally, the medical polymer has the structure shown in formula (3), formula (4) or formula (5).

[0011]

[0012] In formula (3), R1 is methylene or ethylene; in formula (4), R2 is methylene or ethylene.

[0013] Optionally, the medical polymer has the structure shown in formula (6), formula (7), or formula (8).

[0014]

[0015] In formula (6), R3 is methylene, ethylene, or a linking bond; in formula (7), R4 is methylene, ethylene, or a linking bond.

[0016] Optionally, the medical polymer has the structure shown in formula (9).

[0017]

[0018] In formula (9), R5 is a methylene group or a linker bond.

[0019] Optionally, the viscosity-average molecular weight of the polyethylene glycol segments in formulas (1), (3) to (9) is 2000 to 20000.

[0020] The present invention also provides a method for preparing the medical polymer described in any one of the above claims, comprising the step of grafting polyethylene glycol onto sodium alginate to prepare polyethylene glycol-modified sodium alginate.

[0021] Optionally, the preparation method of the medical polymer includes: adding sodium alginate, carbodiimide and N-hydroxysuccinimide to deionized water, stirring and reacting thoroughly, then adding excess polyethylene glycol, continuing to stir and react thoroughly at room temperature, dialysis, and freeze-drying to obtain polyethylene glycol modified sodium alginate.

[0022] Optionally, the polyethylene glycol is a functionalized polyethylene glycol, which is a diamino polyethylene glycol, a dicarboxylated polyethylene glycol, or an aminocarboxylated polyethylene glycol, and the viscosity-average molecular weight of the functionalized polyethylene glycol is 2000 to 20000.

[0023] Optionally, the viscosity-average molecular weight of the functionalized polyethylene glycol is 5000 to 10000.

[0024] Optionally, the viscosity-average molecular weight of the sodium alginate is 100,000 to 300,000.

[0025] Optionally, the mass ratio of sodium alginate to polyethylene glycol is less than 1:5, the concentration of sodium alginate is 0.01-1 g / mL, and the concentration of polyethylene glycol is 0.01-1 g / mL; the reaction time at room temperature with thorough stirring is 4-24 h.

[0026] Optionally, the preparation method of the medical polymer includes the step of grafting selenocysteine ​​or L-selenocysteine ​​onto the polyethylene glycol-modified sodium alginate to prepare the medical polymer.

[0027] Optionally, the preparation method of the medical polymer includes: adding the polyethylene glycol-modified sodium alginate to a tetrahydrofuran solution, stirring to dissolve, adding selenocysteine ​​or L-selenocysteine, stirring to react, adding an aqueous solution of carbodiimide and an aqueous solution of N-hydroxysuccinimide, continuing to stir to react, evaporating water, adding icy ethanol to form a precipitate, filtering, and vacuum drying to obtain the medical polymer.

[0028] Optionally, the mass ratio of the polyethylene glycol-modified sodium alginate to L-selenocysteine ​​or selenocystamine is 1:1 to 5:1, the concentration of the polyethylene glycol-modified sodium alginate is 0.1 to 1 g / mL, the concentration of selenocystamine or L-selenocysteine ​​is 0.1 to 0.5 g / mL, and the stirring reaction time is 4 to 24 h.

[0029] The present invention also provides an artificial blood vessel comprising the medical polymer described in any of the preceding claims.

[0030] The present invention also provides a medical device coating comprising the medical polymer described in any of the preceding claims.

[0031] Beneficial effects: Compared with the prior art, the present invention has the following significant advantages:

[0032] (1) The medical polymer provided by this invention not only endows materials or devices with good hydrophilicity, blood compatibility, and endothelial repair and regeneration capabilities, but also possesses a three-dimensional biomimetic structure of the natural endothelial glycocalyx layer, which can better promote the repair and regeneration of vascular endothelium. Therefore, the medical polymer provided by this invention has multiple physiological functions and can be used in the surface coating of artificial vascular grafts or medical devices such as vascular stents, thrombus filters, and interventional balloon catheters.

[0033] (2) The synthesis conditions used in the present invention for the modified sodium alginate are mild and do not require special conditions and equipment. Therefore, the process cost is low, the controllability is strong, and the effect is significant. Attached Figure Description

[0034] Other features and advantages of the invention will be better understood through the following detailed description of alternative embodiments in conjunction with the accompanying drawings, in which the same reference numerals denote the same or similar parts, wherein:

[0035] Figure 1 This is a schematic diagram of the preparation route of sodium alginate medical polymer that can catalytically release NO in Example 1;

[0036] Figure 2 The infrared spectrum of sodium alginate medical polymer that can catalytically release NO, prepared in Example 1;

[0037] Figure 3 XPS spectrum of sodium alginate medical polymer that can catalytically release NO, prepared in Example 1;

[0038] Figure 4 The graph shows the rate of catalytic NO release obtained from the experiment in Example 3;

[0039] Figure 5 The image shows an electron micrograph of platelet adhesion obtained according to the experiment in Example 4.

[0040] Figure 6 This is a test graph of platelet activation obtained according to the experiment in Example 4;

[0041] Figure 7 This is a diagram showing the endothelial cell adhesion results obtained from the endothelial cell adhesion experiment according to Example 5;

[0042] Figure 8 This is a diagram showing the endothelial cell proliferation results obtained from the endothelial cell proliferation experiment according to Example 5. Detailed Implementation

[0043] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. In the drawings, the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and should not be construed as limiting the present invention.

[0044] The inventors discovered that sodium alginate possesses certain anticoagulant properties, but it cannot induce the repair and regeneration of natural vascular endothelial cells. To enhance the multifunctional bioactivity of sodium alginate, further modifications were made. Selenocysteine-modified sodium alginate (SA-NO) was prepared by grafting selenocysteine ​​onto sodium alginate (SA). SA-NO exhibits the ability to catalyze the release of NO, but its resistance to biofouling is weak, and it has strong water solubility, resulting in insufficient stability in the human vascular environment.

[0045] By grafting L-selenocysteine ​​onto amino-modified polyethylene glycol (PEG), modified polyethylene glycol (PEG-NO) is obtained. PEG-NO has the function of preventing the adhesion and aggregation of plasma proteins and blood cells, and also has the ability to catalyze the release of NO. However, PEG-NO is not easy to form a polymer coating and is difficult to apply directly to the coating surface of medical devices.

[0046] The medical polymer shown in formula (1) is used as a coating for artificial blood vessel materials or medical devices. In formula (1), when Y is amino, carboxyl or hydroxyl, the medical polymer in formula (1) is a polymer material (SA-PEG) formed by grafting modified polyethylene glycol onto sodium alginate. SA-PEG has good anticoagulant properties, hydrophilicity and biocompatibility, and can prevent the formation of thrombi.

[0047] In formula (1), when Y has the structure shown in formula (2), the medical polymer in formula (1) is a polymer (SA-PEG-NO) grafted with polyethylene glycol onto sodium alginate and then grafted with selenocystine or L-selenocysteine. SA-PEG-NO has excellent hydrophilicity, anticoagulant properties, catalytic NO release properties, and endothelial cell proliferation promotion properties. Furthermore, SA-PEG-NO can form a coating on the surface of medical devices, and can also exist stably in the environment of human blood vessels and exert its biological functions. It also possesses a three-dimensional biomimetic structure of the natural endothelial glycocalyx layer, which can better promote the repair and regeneration of vascular endothelium. Therefore, SA-PEG-NO can be applied to small-diameter artificial blood vessels as well as blood contact materials and device surface coatings.

[0048] This invention provides a medical polymer according to the following specific embodiments, having the structural formula shown in formula (1).

[0049]

[0050] In formula (1), ~~~ represents sodium alginate segments, and X represents the connecting structure.

[0051] It should be noted that Equation (1) shows the repeating characteristic branches on the sodium alginate chain segment, but does not limit the sodium alginate chain segment to only 3 branches.

[0052] In formula (1), Y is an amino group, a carboxyl group, a hydroxyl group, or the structure shown in formula (2).

[0053]

[0054] In equation (2), Z is the connecting structure and R is a carboxyl group or a hydrogen atom.

[0055] In some specific embodiments of the medical polymer of the present invention, the structural formula shown in formula (1) is the structure shown in formula (3), formula (4) or formula (5).

[0056]

[0057] In formula (3), R1 is methylene or ethylene; in formula (4), R2 is methylene or ethylene.

[0058] In some specific embodiments of the medical polymer of the present invention, the structural formula shown in formula (1) is the structure shown in formula (6), formula (7) or formula (8).

[0059]

[0060] In formula (6), R3 is methylene, ethylene, or a linking bond; in formula (7), R4 is methylene, ethylene, or a linking bond.

[0061] In some specific embodiments of the medical polymer of the present invention, the structural formula shown in formula (1) is the structure shown in formula (9).

[0062]

[0063] In formula (9), R5 is a methylene group or a linker bond.

[0064] The medical polymer of the specific embodiments of the present invention, in formulas (1), (3) to (9), -(CH2CH2O)- nThe repeating structural unit of polyethylene glycol (PEG) is used. Considering that if the molecular weight of the PEG segments is too low, the resulting medical polymer will have poor hydrophilicity, anticoagulant properties, and biocompatibility; conversely, if the molecular weight of the PEG is too high, the resulting medical polymer will have excessive hydrophilicity and inhibit endothelial cell adhesion, which is detrimental to endothelial cell proliferation. Therefore, considering the biological function of medical polymers in promoting endothelial cell proliferation, the viscosity-average molecular weight of the PEG corresponding to the repeating structural unit is 2000–20000. In some specific embodiments, preferably, the viscosity-average molecular weight of the PEG corresponding to the repeating structural unit is 5000–10000.

[0065] The present invention also provides a method for preparing the above-mentioned medical polymer, comprising the following steps: grafting polyethylene glycol onto sodium alginate to prepare polyethylene glycol-modified sodium alginate.

[0066] In some specific embodiments of the preparation method of the medical polymer of the present invention, the polyethylene glycol is preferably a functionalized polyethylene glycol, including: diamino polyethylene glycol, dicarboxylated polyethylene glycol, or aminocarboxylated polyethylene glycol. The polyethylene glycol is functionalized at both ends by amino or carboxyl groups. Amino-functionalized polyethylene glycol reacts with the carboxyl groups on the sodium alginate chain segment, and carboxyl-functionalized polyethylene glycol reacts with the hydroxyl groups on the sodium alginate chain. This grafting reaction is easier to achieve compared to unfunctionalized polyethylene glycol.

[0067] In some specific embodiments of the preparation method of the medical polymer described in this invention, the viscosity-average molecular weight of the functionalized polyethylene glycol is 2000-20000. Preferably, the viscosity-average molecular weight of the functionalized polyethylene glycol is 5000-10000. Grafting functionalized polyethylene glycol onto sodium alginate requires controlling the molecular weight of the polyethylene glycol within a suitable range: on the one hand, if the molecular weight of the functionalized polyethylene glycol is too large, the stability of the prepared polyethylene glycol-modified sodium alginate will decrease due to the excessively long polyethylene glycol chain segments and steric hindrance, potentially leading to branch breakage. Simultaneously, endothelial cell proliferation requires specific conditions, and excessively large polyethylene glycol molecular weight results in excessive hydrophilicity and inhibits endothelial cell adhesion, which is detrimental to endothelial cell proliferation. On the other hand, if the molecular weight of the functionalized polyethylene glycol is too small, the prepared polyethylene glycol-modified sodium alginate will have relatively low hydrophilicity and biocompatibility, and low anticoagulant properties, which is also detrimental to endothelial cell proliferation.

[0068] In some specific embodiments of the preparation method of the medical polymer described in this invention, the viscosity-average molecular weight of sodium alginate is 100,000 to 300,000. The molecular weight of sodium alginate affects the length of the polymer chain segments of the polyethylene glycol-modified sodium alginate obtained in the final preparation. A suitable molecular weight results in better anticoagulant properties and endothelial cell proliferation promotion properties in applications.

[0069] In some specific embodiments of the preparation method of the medical polymer described in the present invention, the preparation of polyethylene glycol modified sodium alginate includes: adding sodium alginate, carbodiimide and N-hydroxysuccinimide to deionized water, stirring the mixture thoroughly, then adding excess polyethylene glycol, continuing to stir the mixture thoroughly at room temperature, dialysis, and freeze-drying to obtain polyethylene glycol modified sodium alginate.

[0070] In some specific embodiments of the preparation method of the medical polymer of the present invention, the mass ratio of sodium alginate to polyethylene glycol is less than 1:5, for example, it can be 1:5, 1:10, 1:15, 1:20, 1:25, 1:30, 1:35, 1:40, 1:45, 1:50, etc.

[0071] In some specific embodiments of the preparation method of the medical polymer described in the present invention, sodium alginate is added to deionized water to obtain a sodium alginate solution with a concentration of 0.01-1 g / mL, specifically, for example, 0.01 g / mL, 0.1 g / mL, 0.2 g / mL, 0.3 g / mL, 0.4 g / mL, 0.5 g / mL, 0.6 g / mL, 0.7 g / mL, 0.8 g / mL, 0.9 g / mL, 1 g / mL, etc.

[0072] In some specific embodiments of the preparation method of the medical polymer described in the present invention, polyethylene glycol is added to a sodium alginate solution, and the concentration of polyethylene glycol is 0.01-1 g / mL, specifically, for example, 0.01 g / mL, 0.1 g / mL, 0.2 g / mL, 0.3 g / mL, 0.4 g / mL, 0.5 g / mL, 0.6 g / mL, 0.7 g / mL, 0.8 g / mL, 0.9 g / mL, 1 g / mL, etc.

[0073] In some specific embodiments of the preparation method of the medical polymer of the present invention, sodium alginate, carbodiimide and N-hydroxysuccinimide are added to deionized water, and the mixture is stirred and reacted thoroughly. Then, excess polyethylene glycol is added, and the mixture is stirred and reacted thoroughly at room temperature for 4 to 24 hours.

[0074] The preparation method of the medical polymer described in the specific embodiments of the present invention includes the following steps in some specific embodiments: grafting selenocysteine ​​or L-selenocysteine ​​onto polyethylene glycol-modified sodium alginate to prepare sodium alginate that catalyzes the release of NO.

[0075] In some specific embodiments of the preparation method of the medical polymer of the present invention, the mass ratio of the polyethylene glycol modified sodium alginate to L-selenocysteine ​​or selenocystamine is 1:1 to 5:1, specifically, it can be 1:1, 1.5:1, 2:1, 2.5:1, 3:1, 3.5:1, 4:1, 4.5:1, 5:1, etc.

[0076] In some specific embodiments of the preparation method of the medical polymer of the present invention, the concentration of the polyethylene glycol modified sodium alginate is 0.1-1 g / mL, specifically, for example, 0.1 g / mL, 0.2 g / mL, 0.3 g / mL, 0.4 g / mL, 0.5 g / mL, 0.6 g / mL, 0.7 g / mL, 0.8 g / mL, 0.9 g / mL, 1 g / mL, etc.

[0077] In some specific embodiments of the preparation method of the medical polymer of the present invention, the concentration of selenocysteine ​​or L-selenocysteine ​​is 0.1-0.5 g / mL, specifically, for example, 0.1 g / mL, 0.2 g / mL, 0.3 g / mL, 0.4 g / mL, 0.5 g / mL, etc.

[0078] In some specific embodiments of the preparation method of the medical polymer described in the present invention, in the reaction for preparing the medical polymer that can catalytically release NO, after adding polyethylene glycol-modified sodium alginate, selenocysteine ​​or L-selenocysteine, carbodiimide aqueous solution and N-hydroxysuccinimide aqueous solution to tetrahydrofuran solution, the reaction time is 4 to 24 hours.

[0079] In some specific embodiments of the preparation method of the medical polymer of the present invention, the carbodiimide is one of 1-(3-dimethylaminopropyl)-3-ethylcarbodiimide hydrochloride, dicyclohexylcarbodiimide, and diisopropylcarbodiimide.

[0080] In some specific embodiments of the preparation method of the medical polymer of the present invention, the concentration of the carbodiimide solution is 2-10 mmol / L, and the concentration of the N-hydroxysuccinimide solution is 2-10 mmol / L. The volume ratio of the added carbodiimide solution to the N-hydroxysuccinimide solution is 1:1 to 4:1.

[0081] The technical solution of the present invention will be further described below through specific embodiments.

[0082] Example

[0083] Test Method Description

[0084] Infrared spectroscopy testing: Testing is performed using an infrared spectrometer;

[0085] XPS test: Tested using an X-ray photoelectron spectroscopy instrument;

[0086] Test for catalytic release of NO: The determination was performed using a chemiluminescent NO analyzer;

[0087] Platelet adhesion assay: The number and morphology of adherent platelets were observed using scanning electron microscopy;

[0088] Platelet activation assay: The assay was performed using enzyme-linked immunosorbent assay (ELISA) and an enzyme-linked immunosorbent assay (ELISA) reader in a GMP140 environment.

[0089] Endothelial cell adhesion assay: Fluorescent images of cells were captured using a fluorescence microscope in a dark environment to observe the adhesion of endothelial cells on the sample surface;

[0090] Endothelial cell proliferation assay: Detection was performed using a CCK-8 assay kit and an enzyme-linked immunosorbent assay (ELISA) reader.

[0091] Example 1

[0092] (1) Preparation of polyethylene glycol modified sodium alginate (SA-PEG): 50g of sodium alginate was added to 100mL of deionized water to prepare a sodium alginate solution with a concentration of 0.5g / mL; 0.5g of carbodiimide and 0.2g of N-hydroxysuccinimide were added to the sodium alginate solution and stirred thoroughly for 8 hours; 20g of diamino polyethylene glycol with a viscosity-average molecular weight of 5000 was added and stirred thoroughly for 4 hours; the solution after reaction was placed in a dialysis bag and dialyzed thoroughly for 48 hours, and the remaining solution was freeze-dried to obtain polyethylene glycol modified sodium alginate;

[0093] (2) Preparation of a medical polymer that can catalytically release NO (SA-PEG-NO): The polyethylene glycol-modified sodium alginate prepared in Example 1 was added to 50 mL of tetrahydrofuran to prepare a tetrahydrofuran solution of polyethylene glycol-modified sodium alginate with a concentration of 0.5 g / mL; 10 g of L-selenocysteine, 10 mL of carbodiimide aqueous solution with a concentration of 0.05 g / mL and 3 mL of N-hydroxysuccinimide aqueous solution with a concentration of 0.05 g / mL were added sequentially to the tetrahydrofuran solution of polyethylene glycol-modified sodium alginate, and the mixture was stirred thoroughly for 8 hours; the water in the reaction solution was evaporated, ice-cold ethanol was added to generate a precipitate, the precipitate was filtered, and the solution was dried under vacuum to obtain a medical polymer that can catalytically release NO.

[0094] Preparation routes of medical polymers that can catalyze the release of NO, such as Figure 1 As shown.

[0095] Example 2

[0096] The medical polymer (SA-PEG-NO) that catalytically releases NO, prepared in Example 1, was characterized by infrared spectroscopy. The NO-releasing medical polymer obtained in Example 1 was dissolved in tetrahydrofuran solution to obtain a 1 mg / mL solution. A thin film material was prepared using a solvent evaporation method. The thin film material was then subjected to infrared spectroscopy measurements at room temperature, with a measurement range of 4000 cm⁻¹. -1 ~400cm -1 The result is as follows Figure 2 As shown, the wavelength is 3420cm. -1 It exhibits a broad hydroxyl absorption peak at a wavelength of 2910 cm⁻¹. -1 and wavelength 2881cm -1 A distinct absorption peak for methyl and methylene groups appears at a wavelength of 1652 cm⁻¹. -1 and wavelength 1488cm -1 The absorption peak at 1720 cm⁻¹ is either an absorption peak of the amide bond or an absorption peak of the ester group. -1 The infrared absorption peak at this point is for the carbonyl group (-C=O), with a wavelength of 1145 cm⁻¹. -1 A strong absorption peak for CO groups appeared at 1145 cm⁻¹. -1 The absorption peak at the point is mainly due to the generation of CO in the polyethylene glycol structure. As can be seen from the above results, a medical polymer that can catalytically release NO was prepared through Example 1.

[0097] The medical polymer that catalytically releases NO, prepared in Example 1, was characterized by XPS, and the results are as follows: Figure 3 As shown, the XPS full spectrum revealed the presence of characteristic elements N and Se on the surface, proving that Example 1 successfully prepared a medical polymer capable of catalytically releasing NO.

[0098] Example 3

[0099] The NO catalytic release behavior of polyethylene glycol-modified sodium alginate (SA-PEG) prepared in Example 1(1) and the catalytically releasing NO medical polymer (SA-PEG-NO) prepared in Example 1(2) was measured. Physiological concentrations of nitrosoglutathione (10 μmol / L) and glutathione (10 μmol / L) were added to 5 mL of simulated human body fluid. The catalytic NO release behavior was determined using a chemiluminescence NO analyzer. The results are as follows: Figure 4As shown, SA-PEG, lacking the grafted selenocysteine, exhibits almost no catalytic NO release characteristic, while SA-PEG-NO demonstrates a significant catalytic NO release, with a release amount of approximately 2.5 mol·cm⁻¹. -2 .min -1 It is within the normal release range of human endothelial cells (0.5~4×10). -10 mol.cm -2 .min -1 ).

[0100] Example 4

[0101] Platelet adhesion and activation experiments were conducted on the polyethylene glycol-modified sodium alginate (SA-PEG) prepared in Example 1 (1) and the medical polymer (SA-PEG-NO) that catalytically releases NO prepared in Example 1 (2). SA-PEG and SA-PEG-NO were spin-coated onto a polystyrene matrix to prepare polymeric thin films. Polystyrene (PS) was used as a control material. In vitro platelet adhesion experiments were conducted with and without NO donor, and with 20 μL of NO donor added. The NO donors were 10 μmol / L glutathione subunit and 10 μmol / L glutathione.

[0102] Fresh human whole blood was centrifuged for 15 min to obtain platelet-rich plasma. 200 μL of this plasma was dropped onto the surface of each sample and incubated at 37°C for 2 h. The samples were then washed with 0.1 mol / L PBS buffer (pH = 7.4), fixed with 2.5% glutaraldehyde solution for 24 h, washed again with PBS buffer, and dehydrated using an ethanol gradient (ethanol concentrations of 50%, 50%, 75%, 90%, 100%, 10 minutes each time). After drying, the adhesion, number, and morphology of platelets were observed using scanning electron microscopy. The results are as follows: Figure 5 As shown.

[0103] Depend on Figure 5 It can be seen that, compared with PS, the number of platelets adhering to the surface of SA-PEG and SA-PEG-NO is very small, while SA-PEG-NO has almost no platelet adhesion on its surface because it can catalyze the release of NO in the presence of the donor.

[0104] GMP140 activated by adherent platelets was measured using enzyme-linked immunosorbent assay (ELISA), and the results are as follows: Figure 6 As shown, the platelet activation level decreased significantly due to the improved anticoagulant properties of the material. For the SA-PEG-NO sample, the activation level of NO decreased significantly in the presence of NO donor due to the catalytic release of NO, indicating that the blood compatibility of the obtained target polymer material was significantly improved.

[0105] Example 5

[0106] Endothelial cell adhesion and endothelial cell proliferation experiments were conducted on the polyethylene glycol modified sodium alginate (SA-PEG) prepared in Example 1 (1) and the medical polymer (SA-PEG-NO) that can catalyze the release of NO prepared in Example 1 (2).

[0107] Endothelial cell adhesion assay: Polymer films were prepared on a polystyrene matrix using a spin-coating method with SA-PEG-NO, SA-PEG, and sodium alginate (SA). Polystyrene (PS) was used as a control. Endothelial cell adhesion assays were performed with and without NO donors (10 μM nitrosoglutathione and glutathione). Samples were placed in 24-well culture plates and irradiated overnight under UV light. The plates were washed twice with physiological saline. Each sample surface was then treated with 1.5 ml of culture medium (DMEM F12 + 5% FBS + 1% Penicillin Streptomycin) and 0.5 ml of endothelial cells (5 × 10⁶ cells / well). 4 Cells (cells / ml) were incubated for 2 days in a 5% CO2 incubator at a constant temperature of 37°C. The culture medium was removed, and the cells were washed twice with physiological saline. The cells were then fixed with 2.5% glutaraldehyde (prepared with physiological saline) at 4°C for 1.5 h. After washing twice more with physiological saline, the cells were stained with rhodamine (prepared with PBS, 10 μg / ml) and DAPI (prepared with UP water, 500 ng / ml). Fluorescent staining images of the cells were captured using a fluorescence microscope (Zeiss, inverted A2) in the dark. Results are as follows: Figure 7 As shown, in the presence of NO donors, the SA-PEG-NO material significantly increases the number of endothelial cells adhering to its surface due to the catalytic release of NO. The target polymer material on the surface can catalyze the release of NO from the NO donors, thereby promoting the adhesion of endothelial cells.

[0108] Endothelial cell proliferation assay: Polymer films were prepared on a polystyrene matrix using a spin-coating method with SA-PEG-NO, SA-PEG, and sodium alginate (SA). Polystyrene (PS) was used as a control. Endothelial cell proliferation was studied using the CCK-8 assay. Samples were placed in culture plates, with 1.5 ml of cell culture medium and 0.5 ml of endothelial cells (5 × 10⁶ cells / well) added to each well. 4Cells / ml) were then incubated for 1 day and 3 days in an incubator with a CO2 concentration of 5% and a constant temperature of 37°C. 0.5 ml of 10% CCK-8 solution (prepared with DMEM F12) was added to each well, and the plate was incubated for 3.5 h. Then, 200 μL of CCK-8 solution was taken from each well, and three parallel samples were taken. The absorbance was measured at 450 nm using a 96-well plate. The results are as follows: Figure 8 As shown, Figure 8 a represents the endothelial cell proliferation status after 1 day of culture. Figure 8 b shows the endothelial cell proliferation after 3 days of culture. It can be seen that for all samples, the proliferation on 3 days was better than that on 1 day. Since PEG has a certain degree of inhibitory effect on cell adhesion, the cell proliferation of PEG grafted into the SA chain segment decreased slightly. However, after the introduction of selenocysteine, since it can catalyze the release of NO from the NO donor to promote the adhesion and proliferation of endothelial cells, regardless of whether it was 1 day or 3 days, the SA-PEG-NO sample showed significant cell proliferation under the catalytic release of NO, indicating that the material that catalyzes the release of NO has a significant effect on promoting cell proliferation.

[0109] The experimental results of Examples 4 and 5 show that SA-PEG-NO has excellent anticoagulant properties and promotes endothelial cell proliferation, making it suitable for use in artificial blood vessel materials and medical device coatings.

[0110] The above description is merely an exemplary embodiment used to illustrate the principles of the present invention and is not intended to limit the scope of protection of the present invention. For those skilled in the art, various modifications and improvements can be made without departing from the spirit and essence of the present invention, and these modifications and improvements are also within the scope of protection of the present invention.

Claims

1. A medical polymer, characterized in that, Having the structural formula shown in equation (1), ， Equation (1) In formula (1), ~~~ represents the sodium alginate chain segment, X represents the linking structure, and -(CH2CH2O)- n The polyethylene glycol repeating structural unit is a polyethylene glycol repeating structural unit, and the viscosity-average molecular weight of the polyethylene glycol segment corresponding to the polyethylene glycol repeating structural unit is 2000~20000; Y represents the structure shown in equation (2). ， Equation (2) In equation (2), Z is the connecting structure and R is a carboxyl group or a hydrogen atom.

2. The medical polymer according to claim 1, characterized in that, Having the structure shown in equation (3), equation (4) or equation (5), ， Equation (3) Equation (4) Equation (5) In formula (3), R1 is methylene or ethylene; in formula (4), R2 is methylene or ethylene.

3. The medical polymer according to claim 1, characterized in that, Having the structure shown in equation (6), equation (7) or equation (8), ， Equation (6) Equation (7) Equation (8) In formula (6), R3 is a methylene, ethylene, or a linking bond; In formula (7), R4 is methylene, ethylene, or a linking bond.

4. The medical polymer according to claim 1, characterized in that, It has the structure shown in equation (9), ， Equation (9) In formula (9), R5 is a methylene group or a linker bond.

5. A method for preparing a medical polymer as described in any one of claims 1 to 4, characterized in that, The steps include: grafting polyethylene glycol onto sodium alginate to prepare polyethylene glycol-modified sodium alginate.

6. The method for preparing the medical polymer according to claim 5, characterized in that, include: Sodium alginate, carbodiimide, and N-hydroxysuccinimide were added to deionized water and stirred thoroughly to react. Then, excess polyethylene glycol was added, and the reaction was continued at room temperature with thorough stirring. After dialyzing, the mixture was freeze-dried to obtain polyethylene glycol-modified sodium alginate.

7. The method for preparing the medical polymer according to claim 5, characterized in that, The polyethylene glycol is a functionalized polyethylene glycol, which is diamino polyethylene glycol, dicarboxylated polyethylene glycol, or aminocarboxylated polyethylene glycol, and the viscosity-average molecular weight of the functionalized polyethylene glycol is 2000~20000.

8. The method for preparing the medical polymer according to claim 7, characterized in that, The functionalized polyethylene glycol has a viscosity-average molecular weight of 5000~10000.

9. The method for preparing the medical polymer according to any one of claims 5 to 8, characterized in that, The viscosity-average molecular weight of the sodium alginate is 100,000 to 300,000.

10. The method for preparing the medical polymer according to any one of claims 6 to 8, characterized in that, The mass ratio of sodium alginate to polyethylene glycol is less than 1:5, the concentration of sodium alginate is 0.01~1g / mL, and the concentration of polyethylene glycol is 0.01~1g / mL; the reaction time at room temperature with thorough stirring is 4~24h.

11. The method for preparing the medical polymer according to any one of claims 5 to 8, characterized in that, The procedure includes the following steps: grafting selenocysteine ​​or L-selenocysteine ​​onto the polyethylene glycol-modified sodium alginate to prepare the medical polymer.

12. The method for preparing the medical polymer according to claim 11, characterized in that, include: The polyethylene glycol-modified sodium alginate was added to a tetrahydrofuran solution and stirred to dissolve. Selenocysteine ​​or L-selenocysteine ​​was added and stirred to react. An aqueous solution of carbodiimide and an aqueous solution of N-hydroxysuccinimide were added and stirred to continue the reaction. Water was evaporated, and ice-cold ethanol was added to form a precipitate. The precipitate was filtered and dried under vacuum to obtain the medical polymer.

13. The method for preparing the medical polymer according to claim 12, characterized in that, The mass ratio of polyethylene glycol-modified sodium alginate to L-selenocysteine ​​or selenocystamine is 1:1 to 5:1, the concentration of polyethylene glycol-modified sodium alginate is 0.1 to 1 g / mL, the concentration of selenocystamine or L-selenocysteine ​​is 0.1 to 0.5 g / mL, and the stirring reaction time is 4 to 24 hours.

14. An artificial blood vessel, characterized in that, Including the medical polymer as described in any one of claims 1 to 4.

15. A medical device coating, characterized in that, Including the medical polymer as described in any one of claims 1 to 4.

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