Temperature-responsive hemoperfusion adsorption resin, preparation method thereof and hemoperfusion device

Abstract

This invention belongs to the field of blood purification technology, and relates to a temperature-responsive hemoperfusion adsorption resin, its preparation method, and a hemoperfusion device. The adsorption resin consists of porous polystyrene-divinylbenzene microspheres and poly(polyethylene glycol methyl ether methacrylate) brushes grafted onto their outer surface and / or the inner wall of the pores. The grafting rate of the polymer brushes is 5-25%, and the adsorption capacity ratio at 20-37℃ to 45-55℃ is >10. The preparation method involves first introducing an initiator containing a benzene ring spacer group onto the surface of the microspheres using 4-(chloromethyl)benzoyl chloride, followed by grafting a temperature-sensitive monomer through polymerization. This resin can achieve reversible regeneration through room temperature adsorption and gentle heating desorption, with a hemolysis rate of <2% and a retention rate of >90% after 10 cycles, thus reducing treatment costs.

Description

Technical Field

[0001] This invention belongs to the field of blood purification technology, and relates to a temperature-responsive blood perfusion adsorption resin, its preparation method, and a blood perfusion device. Background Technology

[0002] Hemoperfusion is a blood purification technique that involves introducing a patient's blood into a perfusion device containing a solid adsorbent, thereby removing endogenous or exogenous toxins through adsorption. Currently, the adsorbent resins used clinically are mostly polystyrene-divinylbenzene type macroporous resins, which have drawbacks such as single-use, high treatment costs, and lack of regeneration.

[0003] In recent years, temperature-responsive adsorbent materials have provided new solutions to the aforementioned problems. For example, patent document CN120695792A discloses a method for preparing a cell inflammatory factor adsorbent, comprising: mixing styrene, divinylbenzene, and hydroxyethyl acrylate, adding a porogen and mesoporous SiO2 nanoparticles to prepare a porous microsphere carrier; mixing chitosan and poly(N-isopropylacrylamide) (PNIPAAm) in acetic acid solution to obtain a temperature-sensitive chitosan hydrogel precursor solution; activating the surface of the porous microsphere carrier with 1-ethyl-(3-dimethylaminopropyl)carbodiimide and N-hydroxysuccinimide; mixing the activated porous microsphere carrier and the temperature-sensitive chitosan hydrogel precursor solution to obtain an aqueous phase; assembling in an oil phase; washing; and drying to obtain the cell inflammatory factor adsorbent. However, there is still room for improvement in the biocompatibility and anticoagulant properties of PNIPAAm.

[0004] In addition, there are existing reports of grafting temperature-sensitive polymer brushes onto the surface of microspheres for the separation and purification of biological substances. These technologies are designed from the outset as optimized biological separation media; their carrier parameters, reaction conditions, functional monomers, and performance indicators are not specifically designed for the requirements of hemoperfusion, and therefore cannot be directly applied to the field of hemoperfusion.

[0005] Therefore, developing a novel temperature-responsive adsorption resin with a wide range of low critical solution temperature (LCST) regulation, structural stability, high clinical convenience, and excellent blood compatibility is of great clinical significance. Summary of the Invention

[0006] Therefore, the present invention aims to provide a temperature-responsive hemoperfusion adsorption resin, which addresses the technical problems of existing hemoperfusion resins being unreusable, difficult to regenerate, and having poor performance in hemoperfusion applications. This resin achieves reversible regeneration through a reversible conformational change of a temperature-sensitive polymer brush, resulting in "room temperature adsorption - gentle heating desorption." This allows for precise control of the resin's adsorption and release of toxins from the blood, thereby enabling resin recycling and providing a clinically friendly hemoperfusion resin regeneration solution.

[0007] The present invention also provides a method for preparing the above-mentioned temperature-responsive blood perfusion adsorption resin. The method introduces an initiator containing a benzene ring spacer group on the surface of polystyrene-divinylbenzene microspheres (PS-DVB) through an acyl chloride reaction under mild conditions. Then, in the presence of a catalyst and ligand, polyethylene glycol methyl ether methacrylate (OEGMA) monomer is polymerized on the surface of the microspheres to form a temperature-sensitive polymer brush, and its grafting rate, chain length and side chain structure are precisely controlled.

[0008] In a first aspect, the present invention further provides a hemoperfusion device containing the above-mentioned temperature-responsive hemoperfusion adsorption resin, which is reusable.

[0009] To achieve the above objectives, the present invention adopts the following technical solution: This invention provides a temperature-responsive blood perfusion adsorption resin, comprising a porous carrier substrate sphere and a temperature-sensitive polymer brush grafted onto the outer surface and / or the inner wall surface of the pores of the porous carrier substrate sphere; the porous carrier substrate sphere is a polystyrene-divinylbenzene microsphere; the temperature-sensitive polymer brush is a poly(polyethylene glycol methyl ether methacrylate) (POEGMA) brush.

[0010] Furthermore, the ratio of the adsorption capacity of the adsorption resin for the target toxin at 20~37℃ to the adsorption capacity at 45~55℃ is greater than 10.

[0011] Furthermore, the polystyrene-divinylbenzene microspheres have a particle size of 300~800μm and a pore size of 10~50nm.

[0012] Furthermore, the poly(polyethylene glycol methyl ether methacrylate) brush is formed by the polymerization of polyethylene glycol methyl ether methacrylate monomer on the surface of microspheres in the presence of a catalyst and ligands.

[0013] Furthermore, the poly(polyethylene glycol methyl ether methacrylate) brush has 2 to 9 ethoxy units in its side chain, corresponding to a LCST of 26 to 90°C.

[0014] Furthermore, the poly(polyethylene glycol methyl ether methacrylate) brush has 4 to 6 ethoxylated units in its side chains, corresponding to a LCST of 45 to 55°C. This preferred range ensures that the polymer brush fully extends at room temperature / body temperature (20 to 37°C) for efficient adsorption; and that the polymer brush completely collapses under mild heating conditions of 45 to 55°C for complete desorption of toxins, while avoiding damage to blood components or the resin structure from high temperatures.

[0015] Furthermore, the grafting rate of the poly(polyethylene glycol methyl ether methacrylate) brush is 5-25%, and the chain length is 10-100 nm. A grafting rate that is too low (<5%) cannot effectively mask the hydrophobic surface of the carrier, affecting blood compatibility and reducing temperature-sensitive response efficiency; a grafting rate that is too high (>25%) may lead to pore blockage, affecting mass transfer and adsorption capacity. The grafting rate is determined by thermogravimetric analysis, specifically: under a nitrogen atmosphere, heating from 30℃ to 800℃ at a heating rate of 10℃ / min, recording the mass loss curve, and calculating the grafting rate (%) as follows: (mass loss of grafted microspheres at 300-500℃ - mass loss of blank microspheres in the same temperature range) / initial mass of grafted microspheres × 100%.

[0016] Furthermore, the hemolysis rate of the adsorption resin is less than 2%, and the adsorption capacity retention rate is greater than 90% after 10 adsorption-desorption cycles.

[0017] Secondly, the present invention further provides a method for preparing the above-mentioned temperature-responsive blood perfusion adsorption resin, comprising the following steps: S1, porous carrier spheres, acid-binding agent and initiator precursor are added to the first solvent and reacted to obtain activated spheres; S2, the activated base spheres, polyethylene glycol methyl ether methacrylate monomer, catalyst and ligand are added to a second solvent to allow the monomer to polymerize on the surface of the activated base spheres, thereby obtaining the temperature-responsive blood perfusion adsorption resin.

[0018] Furthermore, the preparation process of the activated base spheres described in S1 is as follows: S11, after the porous carrier spheres are added to the first solvent and swollen for 1.5 to 2.5 hours, an acid-binding agent is added; S12, first add the initiator precursor dropwise under ice bath conditions, keep the temperature <5℃ until the dropwise addition is completed, then raise the temperature to 20~30℃, and react for 24±2 hours to obtain the crude activated base spheres; S13, the activated base spheres are obtained by washing and drying the crude activated base spheres; Preferably, the crude activated base spheres in S13 are first washed 2-4 times each with dichloromethane, ethanol, and deionized water, and then vacuum dried at 35-45°C to constant weight to obtain activated base spheres. The surface of the activated base spheres has initiating groups. Preferably, the content of the initiating groups is 0.25-0.35 mmol / g.

[0019] Furthermore, the preparation process of the temperature-responsive blood perfusion adsorption resin described in S2 is as follows: S21, polyethylene glycol methyl ether methacrylate monomer is added to the second solvent, and nitrogen gas is introduced into the system to remove oxygen; S22, the catalyst and ligand are added to the system, and nitrogen is continued to be introduced to remove oxygen; S23, after adding the activated base spheres to the system and sealing it, the polymerization reaction was carried out at 20~30℃ for 2~24 hours to obtain the crude product of temperature-responsive blood perfusion adsorption resin; S24, the temperature-responsive blood perfusion adsorption resin crude product is washed and dried to obtain the temperature-responsive blood perfusion adsorption resin. Preferably, the crude temperature-responsive blood perfusion adsorption resin described in S24 is first washed thoroughly with methanol, 50 mmol / L ethylenediaminetetraacetic acid (EDTA) solution, and deionized water until the washing solution is colorless and free of ion residue, and then vacuum dried at 35~45℃ for 24±1 hours to obtain the final product.

[0020] Further, the mass ratio of the porous support spheres, the first solvent, the acid-binding agent, and the initiator precursor in S1 is 1:(10~15):(0.25~0.35):(0.4~0.5); the first solvent includes anhydrous dichloromethane, the acid-binding agent includes triethylamine, and the initiator precursor includes 4-(chloromethyl)benzoyl chloride.

[0021] Further, in S2, the mass ratio of the activated spheres to polyethylene glycol methyl ether methacrylate monomer, catalyst, ligand, and second solvent is 1:(0.8~1.2):(0.01~0.03):(0.04~0.06):(8~10); the catalyst includes cuprous bromide (CuBr), the ligand includes pentamethyldiethylenetriamine (PMDETA), and the second solvent includes a mixed solution of methanol and water, wherein the volume ratio of methanol to water is preferably 1:1.

[0022] Thirdly, the present invention provides a hemoperfusion device containing the above-mentioned temperature-responsive hemoperfusion adsorption resin, and the hemoperfusion device is a reusable hemoperfusion device.

[0023] The beneficial effects of this invention are: 1. In this invention, 4-(chloromethyl)benzoyl chloride is used for the surface immobilization reaction of polystyrene-divinylbenzene microspheres. This reagent contains a benzene ring spacer group (-C6H4-), which has similar aromaticity to the benzene ring structure of the polystyrene support. The covalent bond formed between the two through electrophilic substitution reaction is more stable and has better interfacial compatibility. The benzene ring spacer group increases the length of the connecting arm between the initiator and the support, giving the subsequently grafted polymer brush a higher degree of freedom of movement. This is beneficial for the temperature-sensitive polymer brush to fully extend and collapse when the temperature changes, thereby obtaining a more significant temperature-sensitive switching effect (adsorption ratio >10).

[0024] 2. This invention covalently grafts a POEGMA temperature-sensitive polymer brush onto the surface of polystyrene-divinylbenzene microspheres and has successfully applied it in the field of hemoperfusion. POEGMA has a polyethylene glycol structure, which effectively resists protein adsorption and platelet adhesion. Experiments have shown that its hemolysis rate is less than 2%, meeting the stringent biosafety requirements for blood contact materials.

[0025] 3. This invention utilizes the precise regulation mechanism of the LCST (lowest calorific value) of POEGMA by the number of ethoxy units (n) in its side chain (n=2~9 corresponds to LCST 26~90℃). By optimizing n=4~6, the LCST is precisely controlled at 45~55℃. This design achieves a clinically friendly regeneration scheme with efficient adsorption at 20~37℃ (room temperature / body temperature) and complete desorption at 45~55℃ (mild heating). It avoids the complex refrigeration equipment required for low-temperature (4℃) desorption and eliminates the risk of protein denaturation that may be caused by high temperatures (>55℃), significantly improving the convenience of clinical operation.

[0026] 4. The polymerization method used in this invention enables the POEGMA polymer brush to be firmly bonded to the carrier surface through stable carbon-carbon covalent bonds. Testing showed that the resin retained more than 90% of its adsorption capacity after 10 adsorption-desorption cycles, demonstrating excellent anti-detachment performance and cycle stability.

[0027] 5. This invention, by adjusting parameters such as polymerization time and monomer ratio, can precisely control the grafting rate (5-25%) and chain length (10-100 nm) of the polymer brush, thereby optimizing the resin's adsorption capacity, thermo-switching effect, and mass transfer performance. The method uses readily available raw materials, has a stable process, and is suitable for industrial production.

[0028] 6. The reusable hemoperfusion device provided by this invention can be used multiple times to treat the same patient, or it can be used for different patients after sterilization. It is expected to solve the clinical pain point of existing perfusion devices being "single-use and costly", and has important economic and social value for patients who need long-term regular treatment.

[0029] 7. This invention systematically screened and compared various initiator precursors (chloroacetyl chloride, 2-bromoisobutyryl bromide, 4-chloromethylbenzoic acid) and various thermosensitive monomers (PNIPAAm, PNIPAMA-co-BMA, MEO2MA / OEGMA). The results showed that only by using 4-(chloromethyl)benzoyl chloride as an initiator, POEGMA (n=4~6) as a thermosensitive polymer brush, and with the preferred grafting process, can the comprehensive excellent performance of high adsorption ratio (>10), high cycling stability (>90%) and low hemolysis rate (<2%) be obtained simultaneously. Attached Figure Description

[0030] To more clearly illustrate the technical solution of the present invention, the drawings used in the embodiments 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.

[0031] Figure 1 This is a summary table of the performance indicators of the resin products in Examples 13-18; Figure 2 This is a summary table of key performance indicators of the resin products in Examples 1-12 and Comparative Examples 1-11; Figure 3 This is a schematic diagram of the stretching and collapse of poly(polyethylene glycol methyl ether methacrylate) brushes on the surface of a temperature-responsive blood perfusion adsorption resin. The left side shows the stretching state at a low temperature of 20-37℃, and the right side shows the collapse state at a high temperature of 45-55℃. Figure 4 Schematic diagram illustrating the introduction of active sites through the reaction of 4-(chloromethyl)benzoyl chloride with polystyrene-divinylbenzene microspheres; Figure 5 This is a schematic diagram of POEGMA grafted onto microspheres; Figure 6 The structural formula is polyethylene glycol methyl ether methacrylate; Figure 7 It has the structural formula of 4-(chloromethyl)benzoyl chloride. Detailed Implementation

[0032] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. All mentioned embodiments are implemented based on the technical solutions of the present invention, and detailed implementation processes are given. However, it should be stated that the scope of protection of the present invention is not limited to the following embodiments.

[0033] The following embodiments provide detailed implementation procedures for the technical solutions of the present invention. Unless otherwise specified, the experimental methods used in the following experimental examples are conventional methods; unless otherwise specified, the materials and reagents used are commercially available.

[0034] Example 1

[0035] Preparation of an adsorption resin for POEGMA with n=2 ethoxy units in the side chain (adsorption 20℃ / desorption 48℃) 1. Preparation of porous carrier-based spheres: Polystyrene-divinylbenzene microspheres were prepared by suspension polymerization. In a 1000 mL reactor, 400 mL of water, 5 g of gelatin, 1.25 g of carboxymethyl cellulose, and 3.3 mL of 0.1% methylene blue were added to the aqueous phase; 181 g of styrene, 19 g of divinylbenzene, 200 g of xylene, and 2 g of benzoyl peroxide were added to the oil phase. The oil phase was poured into the aqueous phase, and the particle size was adjusted to 0.4-0.8 mm. The temperature program was as follows: 80 °C for 3.5 hours → 90 °C for 3 hours → 95 °C for 6 hours. After the reaction, the temperature was lowered. The porogen was extracted with methylal, and the microspheres were boiled, washed, and dried to obtain porous polystyrene-divinylbenzene microspheres with a particle size of 400-600 μm and an average pore size of 25 nm.

[0036] 2. Surface activation of porous polystyrene-divinylbenzene microspheres: 10 g of the dried microspheres prepared in step 1 were added to 100 mL of anhydrous dichloromethane and swollen for 2 hours. 4 mL of triethylamine was added, and the mixture was cooled to 0°C in an ice bath. 4.5 g of 4-(chloromethyl)benzoyl chloride was slowly added dropwise, maintaining the temperature <5°C during the addition process. After the addition was complete, the reaction was allowed to proceed at room temperature for 24 hours. The reaction product was washed three times each with dichloromethane, ethanol, and deionized water, and dried under vacuum at 40°C to constant weight to obtain 4-(chloromethyl)benzoyl functionalized microspheres. Elemental analysis showed that the content of surface initiating groups (calculated as chlorine) was 0.30 mmol / g.

[0037] 3. Polymerization reaction of POEGMA grafting on the microsphere surface: In a 250 mL Schranke flask, add 10 g of OEGMA (n=2 side chain ethoxy units, number-average molecular weight Mn=188; CAS No. 26915-72-0, supplier Sigma-Aldrich, product model / catalog number 447935) and 100 mL of methanol / water mixture (1:1 v / v), and purge with nitrogen for 30 minutes. Quickly add 0.2 g of cuprous bromide and 0.6 mL of PMDETA, and continue purging with nitrogen for 15 minutes. Add 10 g of the microspheres prepared in step 2, seal, and polymerize at 25 °C for 12 hours. After the reaction, wash the microspheres thoroughly with methanol, 50 mmol / L EDTA solution, and deionized water sequentially until the washing solution is colorless and free of copper ion residue. Vacuum dry at 40 °C for 24 hours to obtain POEGMA-grafted polystyrene microspheres, i.e., temperature-responsive blood perfusion adsorption resin.

[0038] 4. Grafting rate determination: Thermogravimetric analysis (TGA) was used. Under a nitrogen atmosphere, the temperature was increased from 30℃ to 800℃ at a rate of 10℃ / min, and the mass loss curve was recorded. Grafting rate (%) = (Mass loss of grafted microspheres at 300~500℃ - Mass loss of blank microspheres in the same temperature range) / Initial mass of grafted microspheres × 100%. The calculated grafting rate in this example was 8.2%.

[0039] 5. Chain length determination: X-ray photoelectron spectroscopy (XPS) combined with elemental analysis was used for estimation. Based on the relative contents of C, O, and Br elements on the surface, and combined with the structural characteristics of the POEGMA repeating units, the average chain length of the polymer brush was estimated to be 15 nm.

[0040] 6. LCST determination: The phase transition temperature of the resin was determined by differential scanning calorimetry (DSC) to be 26.8℃.

[0041] 7. Adsorption performance test: Using bovine serum albumin-bound bilirubin as a model toxin, the static adsorption capacity was 45.2 mg / g at 20℃ for 2 hours; the adsorption capacity was 4.1 mg / g at 48℃, and the adsorption ratio at 20℃ / 48℃ was 11.0.

[0042] 8. Cyclic stability test: The resin saturated with adsorption at 20℃ was placed in phosphate buffered saline (PBS) at 48℃ for 2 hours for desorption, and the desorption rate reached 90.5%. After 10 adsorption-desorption cycles, the adsorption capacity remained at 90.8% of the initial value.

[0043] 9. Blood compatibility test: Hemolysis rate 1.8%, platelet adhesion significantly inhibited, and clotting time prolonged.

[0044] Example 2

[0045] Preparation of an adsorption resin for POEGMA with 3 ethoxy units in the side chain (adsorption 22℃ / desorption 45℃) The monomer was changed to OEGMA with 3 side chain ethoxy units (number average molecular weight Mn=244), and other conditions were the same as in Example 1.

[0046] Performance testing: LCST 35.6℃; adsorption capacity at 22℃ 51.3 mg / g, adsorption capacity at 45℃ 4.8 mg / g, adsorption ratio 10.7; adsorption capacity retention after 10 cycles 91.2%; grafting rate 8.5%, chain length 18 nm; hemolysis rate 1.7%.

[0047] Example 3

[0048] Preparation of an adsorption resin for POEGMA with 4 ethoxy units in the side chain (adsorption 20℃ / desorption 48℃) The monomer used was OEGMA (number average molecular weight Mn=300) with 4 ethoxy units in the side chain. The polymerization time was 12 hours, and other conditions were the same as in Example 1.

[0049] Performance testing: LCST 48.5℃; adsorption capacity at 20℃ 58.7mg / g, adsorption capacity at 48℃ 5.4mg / g, adsorption ratio 10.9; adsorption capacity retention after 10 cycles 91.3%; grafting rate 9.1%, chain length 22nm; hemolysis rate 1.6%.

[0050] Example 4

[0051] Preparation of an adsorption resin with n=4 ethoxy units in the POEGMA side chain (adsorption 25℃ / desorption 50℃) The monomer used was OEGMA (number average molecular weight Mn=300) with 4 ethoxy units in the side chain. The polymerization time was 14 hours, and other conditions were the same as in Example 1.

[0052] Performance testing: LCST 48.5℃; adsorption capacity at 25℃ 62.1 mg / g, adsorption capacity at 50℃ 5.6 mg / g, adsorption ratio 11.1; adsorption capacity retention after 10 cycles 91.5%; grafting rate 10.2%, chain length 28 nm; hemolysis rate 1.6%.

[0053] Example 5

[0054] Preparation of an adsorption resin for POEGMA with 5 ethoxy units in the side chain (adsorption 22℃ / desorption 46℃) The monomer used was OEGMA (number average molecular weight Mn=500) with 5 ethoxy units in the side chain, and the polymerization time was 10 hours. Other conditions were the same as in Example 1.

[0055] Performance testing: LCST 51.2℃; adsorption capacity at 22℃ 60.1 mg / g, adsorption capacity at 46℃ 5.6 mg / g, adsorption ratio 10.7; adsorption capacity retention after 10 cycles 91.0%; grafting rate 9.5%, chain length 25 nm; hemolysis rate 1.6%.

[0056] Example 6

[0057] Preparation of an adsorption resin for POEGMA with 5 ethoxy units in the side chain (adsorption 25℃ / desorption 50℃) The monomer used was OEGMA (number average molecular weight Mn=500) with 5 ethoxy units in the side chain. The polymerization time was 12 hours, and other conditions were the same as in Example 1.

[0058] Performance testing: LCST 51.2℃; adsorption capacity at 25℃ 63.5mg / g, adsorption capacity at 50℃ 5.3mg / g, adsorption ratio 12.0; adsorption capacity retention after 10 cycles 92.5%; grafting rate 11.8%, chain length 32nm; hemolysis rate 1.5%.

[0059] Example 7

[0060] Preparation of an adsorption resin for POEGMA with 5 ethoxy units in the side chain (adsorption 28℃ / desorption 52℃) The monomer used was OEGMA (number average molecular weight Mn=500) with 5 ethoxy units in the side chain. The polymerization time was 16 hours, and other conditions were the same as in Example 1.

[0061] Performance testing: LCST 51.2℃; adsorption capacity at 28℃ 61.8 mg / g, adsorption capacity at 52℃ 5.1 mg / g, adsorption ratio 12.1; adsorption capacity retention after 10 cycles 91.8%; grafting rate 13.5%, chain length 38 nm; hemolysis rate 1.5%.

[0062] Example 8

[0063] Preparation of an adsorption resin for POEGMA with 6 ethoxy units in the side chain (adsorption 24℃ / desorption 49℃) The monomer used was OEGMA (number average molecular weight Mn=800) with 6 ethoxy units in the side chain. The polymerization time was 12 hours, and other conditions were the same as in Example 1.

[0064] Performance testing: LCST 54.8℃; adsorption capacity at 24℃ 58.5mg / g, adsorption capacity at 49℃ 5.2mg / g, adsorption ratio 11.3; adsorption capacity retention after 10 cycles 91.1%; grafting rate 10.5%, chain length 30nm; hemolysis rate 1.6%.

[0065] Example 9

[0066] Preparation of an adsorption resin for POEGMA with 6 ethoxy units in the side chain (adsorption 30℃ / desorption 53℃) The monomer used was OEGMA (number average molecular weight Mn=800) with 6 ethoxy units in the side chain. The polymerization time was 12 hours, and other conditions were the same as in Example 1.

[0067] Performance testing: LCST 54.8℃; adsorption capacity at 30℃ 59.8 mg / g, adsorption capacity at 53℃ 5.1 mg / g, adsorption ratio 11.7; adsorption capacity retention after 10 cycles 91.8%; grafting rate 10.8%, chain length 31 nm; hemolysis rate 1.5%.

[0068] Example 10

[0069] Preparation of an adsorption resin for POEGMA with 6 ethoxy units in the side chain (adsorption 35℃ / desorption 55℃) The monomer used was OEGMA (number average molecular weight Mn=800) with 6 ethoxy units in the side chain. The polymerization time was 12 hours, and other conditions were the same as in Example 1.

[0070] Performance testing: LCST 54.8℃; adsorption capacity at 35℃ 57.6 mg / g, adsorption capacity at 55℃ 4.8 mg / g, adsorption ratio 12.0; adsorption capacity retention after 10 cycles 91.3%; grafting rate 10.2%, chain length 29 nm; hemolysis rate 1.6%.

[0071] Example 11

[0072] Preparation of an adsorption resin with 8 ethoxy units in the POEGMA side chain (adsorption 26℃ / desorption 51℃) The monomer used was OEGMA (number average molecular weight Mn=950) with 8 ethoxy units in the side chain. The polymerization time was 12 hours, and other conditions were the same as in Example 1.

[0073] Performance testing: LCST 69.2℃; adsorption capacity at 26℃ 52.4 mg / g, adsorption capacity at 51℃ 4.6 mg / g, adsorption ratio 11.4; adsorption capacity retention after 10 cycles 90.5%; grafting rate 9.2%, chain length 24 nm; hemolysis rate 1.7%.

[0074] Example 12

[0075] Preparation of an adsorption resin with POEGMA side chain ethoxy units n=9 (adsorption 32℃ / desorption 54℃) The monomer used was OEGMA with 9 side chain ethoxy units (number average molecular weight Mn=1100), the polymerization time was 12 hours, and other conditions were the same as in Example 1.

[0076] Performance testing: LCST 86.5℃; adsorption capacity at 32℃ 49.8 mg / g, adsorption capacity at 54℃ 4.3 mg / g, adsorption ratio 11.6; adsorption capacity retention after 10 cycles 90.2%; grafting rate 8.8%, chain length 21 nm; hemolysis rate 1.8%.

[0077] Examples 13-18 (Effect of polymerization time on grafting rate and performance) Using the formulation of Example 6 (n=5), polymerization was carried out for 4 hours (Example 13), 8 hours (Example 14), 12 hours (Example 15), 16 hours (Example 16), 20 hours (Example 17), and 24 hours (Example 18), respectively, to investigate the effect of grafting rate on performance. The performance indicators of the resin products in Examples 13-18 are summarized as follows: Figure 1 As shown.

[0078] Depend on Figure 1Data shows that the adsorption ratio is highest (and the switching effect is most pronounced) during polymerization at 12-16 hours, and the overall performance is optimal when the grafting rate is in the range of 11.8-15.2%. When the grafting rate is below 5% (Example 13), the temperature-sensitive switching effect is weak, and the adsorption ratio is only 3.1; when the grafting rate is above 25% (Example 18), the adsorption ratio drops to 9.5, and the cycle stability decreases slightly. Therefore, a grafting rate of 5-25% is preferred, and 10-20% is more preferred.

[0079] Comparative Example 1 (Blank polystyrene-divinylbenzene microspheres) The polystyrene-divinylbenzene microspheres prepared in step 1 of Example 1 were used directly as adsorption resins for testing without surface activation and graft polymerization.

[0080] Performance testing: Adsorption capacity at 25℃: 18.5 mg / g Adsorption capacity at 50℃: 17.2 mg / g Adsorption ratio: 1.08 (no temperature-sensitive switching effect) Recycling: No temperature-sensitive properties Hemolysis rate: 3.2%, with significant platelet adhesion. Comparative Example 2 (PNIPAAm copolymer modified resin) Polystyrene-divinylbenzene-PNIPAAm copolymer microspheres were prepared by suspension polymerization. 15 g of N-isopropylacrylamide (NIPAAm) monomer was added to the oil phase, and other conditions were the same as in step 1 of Example 1. PNIPAAm was introduced into the resin backbone through copolymerization.

[0081] Performance testing: LCST: 34.2℃ Adsorption capacity at 25℃: 38.2 mg / g; adsorption capacity at 40℃: 24.5 mg / g; adsorption ratio at 25℃ / 40℃: 1.56 After 10 adsorption-desorption cycles (adsorption at 25℃, desorption at 40℃), the adsorption capacity decreased to 24.6 mg / g (retention rate 64.4%). Hemolysis rate: 3.5%, with significant platelet adhesion. Comparative Example 3 (PEGMA conventional free radical grafted resin) Surface grafting was performed using a traditional free radical polymerization method. 10g of dried polystyrene-divinylbenzene microspheres were swollen in 100ml of ethanol, followed by the addition of 0.3g of azobisisobutyronitrile (AIBN) and 5g of PEGMA monomer (n=5, Mn=500). The reaction was carried out at 70℃ for 12 hours. After the reaction, the microspheres were washed and dried.

[0082] Performance testing: No clear LCST Adsorption capacity at 25℃: 32.5 mg / g; adsorption capacity at 50℃: 22.8 mg / g; adsorption ratio: 1.43 After 10 adsorption-desorption cycles (adsorption at 25℃, desorption at 50℃), the adsorption capacity decreased to 19.8 mg / g (retention rate 60.9%). Hemolysis rate: 2.8% Comparative Example 4 (PHEMA Copolymer Resin) Polystyrene-divinylbenzene-hydroxyethyl methacrylate (HEMA) copolymer microspheres were prepared by suspension polymerization. 15 g of HEMA monomer was added to the oil phase, and other conditions were the same as in step 1 of Example 1.

[0083] Performance testing: No obvious LCST Adsorption capacity at 25℃: 30.2 mg / g; adsorption capacity at 50℃: 29.5 mg / g; adsorption ratio: 1.02 Lacking temperature-sensitive properties, it cannot perform temperature-responsive regeneration. Hemolysis rate: 2.5% Comparative Example 5 (Macroporous silica gel-based POEGMA grafted resin) Macroporous silica microspheres (particle size 400-600 μm, pore size 25 nm) were used as a carrier. Surface activation and grafting (n=5) were carried out according to steps 2-3 of Example 1. However, in the activation step, a conventional silane coupling agent (3-aminopropyltriethoxysilane) was used to connect bromoisobutyryl bromide.

[0084] Performance testing: LCST: 51.5℃ Adsorption capacity at 25℃: 15.6 mg / g; adsorption capacity at 50℃: 8.2 mg / g; adsorption ratio: 1.90 Adsorption capacity retention after 10 cycles: 72.3% Hemolysis rate: 3.2%, with significant platelet adhesion. Comparative Example 6 (using chloroacetyl chloride as an initiator precursor) Referring to Example 6, the initiator precursor in S1 was replaced with chloroacetyl chloride instead of 4-(chloromethyl)benzoyl chloride, and the amount was adjusted to 2.5g, while other conditions remained unchanged.

[0085] Performance testing: Surface chlorine content: 0.28 mmol / g Grafting rate: 10.5% LCST: 51.0℃ Adsorption capacity at 25℃: 58.2 mg / g; adsorption capacity at 50℃: 9.8 mg / g; adsorption ratio: 5.9 Retention rate after 10 cycles: 78.5% Hemolysis rate: 2.3% Note: When using chloroacetyl chloride, the polymer brush has limited freedom of movement due to the absence of benzene ring spacer groups, resulting in significantly lower temperature-sensitive switching effect and cycle stability compared to the preferred embodiment of this invention.

[0086] Comparative Example 7 (using 2-bromoisobutyryl bromide as an initiator precursor) Referring to Example 6, the initiator precursor in S1 was replaced with 2-bromoisobutyryl bromide instead of 4-(chloromethyl)benzoyl chloride, and the amount was adjusted to 4.0 g, while other conditions remained unchanged.

[0087] Performance testing: Surface bromine content: 0.32 mmol / g Grafting rate: 11.2% LCST: 51.2℃ Adsorption capacity at 25℃: 59.5 mg / g; adsorption capacity at 50℃: 11.2 mg / g; adsorption ratio: 5.3 Retention rate after 10 cycles: 72.8% Hemolysis rate: 2.6% Note: When using 2-bromoisobutyryl bromide, the reaction activity is high, the controllability is poor, and there is no benzene ring spacer group. The temperature-sensitive switching effect and cycle stability are significantly lower than those of the preferred embodiment of this invention.

[0088] Comparative Example 8 (using 4-chloromethylbenzoic acid as an initiator precursor) Referring to Example 6, the initiator precursor in S1 was replaced with 4-chloromethylbenzoic acid instead of 4-chloromethylbenzoic acid, and 1-ethyl-(3-dimethylaminopropyl)carbodiimide (EDC) was added as a condensing agent, while other conditions remained unchanged.

[0089] Performance testing: Surface chlorine content: 0.15 mmol / g Grafting rate: 4.8% LCST: 50.5℃ Adsorption capacity at 25℃: 38.5 mg / g; adsorption capacity at 50℃: 14.2 mg / g; adsorption ratio: 2.7 Retention rate after 10 cycles: 58.2% Hemolysis rate: 3.0% Note: When using 4-chloromethylbenzoic acid (non-acyl chloride), the grafting efficiency is low, the surface initiation sites are few, resulting in low grafting rate, insufficient polymer brush coverage, weak temperature-sensitive switching effect, and poor circulatory stability and blood compatibility.

[0090] Comparative Example 9 (using PNIPAAm as the temperature-sensitive monomer) Referring to Example 6, the temperature-sensitive monomer in S2 was replaced by N-isopropylacrylamide (NIPAM) instead of OEGMA (n=5), and the amount was adjusted to an equimolar amount, while other conditions remained unchanged.

[0091] Performance testing: Grafting rate: 10.8% LCST: 32.5℃ Adsorption capacity at 25℃: 52.3 mg / g; adsorption capacity at 40℃: 31.5 mg / g; adsorption ratio: 1.66 Retention rate after 10 cycles: 68.5% (adsorption at 25℃, desorption at 40℃) Hemolysis rate: 3.2% Note: PNIPAAm has an LCST of approximately 32°C, making it unable to desorb above 45°C. It also exhibits a weak temperature-sensitive switching effect, poor circulatory stability, and poor blood compatibility.

[0092] Comparative Example 10 (using PNIPAAm-co-BMA copolymer as temperature-sensitive monomer) Referring to Example 6, the temperature-sensitive monomer in S2 was replaced with a mixture of N-isopropylacrylamide (NIPAM) and butyl methacrylate (BMA) (molar ratio 95:5), with the total molar amount being the same as OEGMA in Example 6, and other conditions remaining unchanged.

[0093] Performance testing: Grafting rate: 11.5% LCST: 34.2℃ Adsorption capacity at 25℃: 54.8 mg / g; adsorption capacity at 40℃: 33.2 mg / g; adsorption ratio: 1.65 Retention rate after 10 cycles: 66.8% Hemolysis rate: 3.5% Note: Although copolymerization can fine-tune LCST, the range is limited and it still cannot reach the 45~55℃ desorption range; after introducing the hydrophobic monomer BMA, blood compatibility is further reduced.

[0094] Comparative Example 11 (using a mixture of MEO2MA and OEGMA as a temperature-sensitive monomer) Referring to Example 6, the thermosensitive monomer in S2 was replaced with a mixture of 2-(2-methoxyethoxy)methacrylate (MEO2MA) and OEGMA (n=5) (molar ratio 85:15), with the total molar amount being the same as that of OEGMA in Example 6, and other conditions remaining unchanged.

[0095] Performance testing: Grafting rate: 11.2% LCST: 38.5℃ Adsorption capacity at 25℃: 56.2 mg / g; adsorption capacity at 45℃: 32.5 mg / g; adsorption ratio: 1.73 Retention rate after 10 cycles: 75.2% Hemolysis rate: 2.2% Note: Although the LCST can be adjusted by copolymerizing MEO2MA and OEGMA, it is difficult to accurately reach the target range of 45~55℃. Moreover, the copolymer chain structure is complex, the temperature-sensitive response is not consistent, and the temperature-sensitive switching effect and cycle stability are lower than those of the pure POEGMA system of this invention.

[0096] The key performance indicators of Examples 1-12 and Comparative Examples 1-11 are summarized as follows: Figure 2 As shown. Detailed results analysis is as follows: 1. Comparative Analysis of Thermosensitive Switching Effect from Figure 2 As can be seen from the data, the adsorption ratios of Examples 1 to 12 of the present invention are all between 10.7 and 12.1, all greater than 10, exhibiting excellent temperature-sensitive switching effect. Among them, Example 6 (n=5, 25℃ / 50℃) has an adsorption ratio of 12.0, Example 7 (n=5, 28℃ / 52℃) has an adsorption ratio of 12.1, and Example 10 (n=6, 35℃ / 55℃) has an adsorption ratio of 12.0, showing the most significant switching effect.

[0097] Comparative Example 1: The adsorption ratio of the blank microspheres was only 1.08, with no temperature-sensitive switching effect. Comparative Example 2: The adsorption ratio of the PNIPAAm copolymer resin was only 1.56; Comparative Example 3: The adsorption ratio of the traditional free radical grafted resin was 1.43; Comparative Example 4: The adsorption ratio of the PHEMA resin was 1.02; Comparative Example 5: The adsorption ratio of the silica gel carrier resin was 1.90, all of which are far lower than those of the preferred embodiment of the present invention.

[0098] As can be seen from Comparative Examples 6-8, when other initiator precursors (chloroacetyl chloride, bromoisobutyryl bromide, 4-chloromethylbenzoic acid) are used, the adsorption ratio is only 2.7-5.9, which is much lower than that of the preferred embodiment (12.0) of the present invention. This indicates that the 4-(chloromethyl)benzoyl chloride selected in the present invention is the key to achieving a high switching effect due to its benzene ring spacer structure and mild reaction characteristics.

[0099] As can be seen from Comparative Examples 9-11, when using other temperature-sensitive monomers (PNIPAAm, PNIPAMA-co-BMA, MEO2MA / OEGMA), the adsorption ratio is only 1.65-1.73, which is much lower than that of the present invention. This indicates that POEGMA (n=5) is the preferred material for achieving high switching effect due to its precise LCST control capability and regular polymer brush structure.

[0100] 2. Adsorption capacity comparison analysis Examples 1-12 of this invention exhibit adsorption capacities ranging from 45.2 to 63.5 mg / g within an adsorption temperature range of 20-37°C. Examples with 4-6 ethoxy units in the side chain generally showed higher adsorption capacities, with Example 6 showing the highest adsorption capacity (63.5 mg / g). The highest adsorption capacity among the comparative examples was 54.8 mg / g in Comparative Example 10, which is still significantly lower than the preferred embodiments of this invention.

[0101] 3. Cyclic Stability Comparison Analysis After 10 adsorption-desorption cycles, the adsorption capacity retention rates of Examples 1-12 of this invention were all between 90.2% and 92.5%. The cycle retention rates of Comparative Examples 6-8 were only 58.2% to 78.5%, and those of Comparative Examples 9-11 were 66.8% to 75.2%, all significantly lower than those of the preferred embodiments of this invention. This indicates that only by using a combination of 4-(chloromethyl)benzoyl chloride and POEGMA, along with a preferred process, can excellent cycle stability be obtained.

[0102] 4. Blood compatibility comparative analysis The hemolysis rates of Examples 1-12 of this invention are all between 1.5% and 1.8%, which is far lower than the requirements for medical materials (<5%). The lowest hemolysis rate among the comparative examples is 2.2% in Comparative Example 11, which is still higher than the preferred embodiment of this invention (1.5%). The hemolysis rates of Comparative Examples 9-10 are as high as 3.2% to 3.5%, indicating that the blood compatibility of PNIPAAm-type materials is poor.

[0103] 5. Comparative Analysis of LCST Control Range This invention achieves precise control of LCST within the range of 26–90°C by changing the number of ethoxy units (n) in the side chain. Preferably, when n = 4–6, the LCST falls precisely within the target range of 45–55°C. The LCSTs of Comparative Examples 9–11 are all below 40°C, failing to achieve the gentle desorption at 45–55°C.

[0104] 6. Overall Effect Analysis pass Figure 2 Data comparison shows that the preferred technical solution of the present invention (Example 6) exhibits the best performance in five aspects: thermosensitive switching effect, adsorption capacity, cyclic stability, blood compatibility, and LCST regulation. Data from Comparative Examples 6-11 indicate that changing the initiator type or the thermosensitive monomer type leads to a significant decrease in at least one key performance characteristic, failing to achieve the comprehensive effect of the preferred solution of the present invention. For example, using different initiators in Comparative Examples 6-8 resulted in an adsorption ratio decrease of over 50% and a cyclic retention rate decrease of 10-30 percentage points; using different thermosensitive monomers in Comparative Examples 9-11 resulted in an adsorption ratio decrease of over 85%, a cyclic retention rate decrease of 17-26 percentage points, and a hemolysis rate increase of 46-133%.

[0105] Among them, Example 6 (n=5 side chain ethoxy units, adsorption 25℃ / desorption 50℃) has the best overall performance, with an adsorption capacity of 63.5 mg / g, an adsorption ratio of 12.0, a retention rate of 92.5% after 10 cycles, and a hemolysis rate of 1.5%, which is the preferred embodiment of the present invention.

[0106] In summary, the POEGMA used in this invention is a typical thermosensitive polymer. Its molecular structure consists of a hydrophobic polymethyl methacrylate backbone and hydrophilic oligoethylene glycol side chains. The number of ethoxy units (n) in the side chains determines the hydrophilic / hydrophobic balance of the polymer. Under low-temperature conditions, a large number of hydrogen bonds are formed between the ethoxy units of the POEGMA side chains and water molecules. Water molecules are arranged in an orderly manner around the polymer chains to form a hydration layer. This hydrogen bonding makes the polymer chains tend to fully extend to expose more hydrophilic sites, and the system is in a stable state with low energy. When the temperature rises above the lower critical solution temperature (LCST), the energy provided by thermal motion is sufficient to break the hydrogen bonds between the ethoxy units and water molecules, causing bound water to be expelled and the polymer chains to dehydrate. At this time, hydrophobic interactions replace hydrogen bonds as the dominant factor. The hydrophobic polymer backbone and the dehydrated side chains aggregate to reduce contact with water, causing the polymer chains to change from an extended state to a collapsed state. Figure 3 This phase transition is entropy-driven—water molecules bound around the polymer chains are released into free water, gaining greater degrees of freedom of motion, increasing the total entropy of the system, and the phase transition occurs spontaneously according to the Gibbs free energy principle. The LCST of POEGMA can be precisely controlled by the number of ethoxy units n in the side chains: a smaller n (2-3) results in shorter side chains, weaker hydrophilicity, and a lower LCST; a moderate n (4-6) provides the optimal hydrophilic / hydrophobic balance, with the LCST precisely falling within the target range; and a larger n (7-9) results in longer side chains, enhanced hydrophilicity, and a higher LCST. Based on this reversible conformational change mechanism, this invention achieves the "low-temperature adsorption-high-temperature desorption" function of the adsorption resin—under specific conditions, the polymer brush extends to expose adsorption sites, efficiently capturing toxin molecules in the blood; under specific conditions, the polymer brush collapses to release toxins, achieving online regeneration of the adsorbent, and this process can be repeated without damaging the material structure.

[0107] This invention uses 4-(chloromethyl)benzoyl chloride ( Figure 7 Using POEGMA as an initiator precursor, covalent grafting of POEGMA onto the surface of polystyrene-divinylbenzene (PS-DVB) porous microspheres was achieved via the above polymerization method. First, during surface activation, 4-(chloromethyl)benzoyl chloride molecules undergo an electrophilic substitution reaction with the benzene ring on the PS microsphere surface in the presence of an acid-binding agent (triethylamine), covalently linking the chloromethylbenzoyl group containing the benzene ring spacer to the microsphere surface, forming initiation sites. Figure 4Subsequently, in the polymerization system, cuprous bromide (CuBr) forms a catalytically active complex with the ligand pentamethyldiethylenetriamine (PMDETA). This complex induces the generation of active species at the initiation sites on the microsphere surface, initiating the polymerization of OEGMA monomer (…). Figure 6 Polymerization occurs on the surface of microspheres, ultimately forming POEGMA polymer brushes. Figure 5 After the polymerization reaction is complete, one end of the POEGMA polymer brush is firmly attached to the surface of the PS microspheres through stable carbon-carbon covalent bonds, ensuring that the polymer brush will not fall off under repeated temperature changes and blood flow.

[0108] The above description is merely a preferred embodiment of the present invention and is not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A temperature-responsive blood perfusion adsorption resin, characterized in that, It includes a porous carrier substrate sphere and a temperature-sensitive polymer brush grafted onto the outer surface and / or inner wall surface of the pores of the porous carrier substrate sphere; the porous carrier substrate sphere is a polystyrene-divinylbenzene microsphere; the temperature-sensitive polymer brush is a poly(polyethylene glycol methyl ether methacrylate) brush.

2. The temperature-responsive blood perfusion adsorption resin according to claim 1, characterized in that, The porous carrier-based spheres have a particle size of 300~800μm and a pore size of 10~50nm.

3. The temperature-responsive blood perfusion adsorption resin according to claim 1, characterized in that, The poly(polyethylene glycol methyl ether methacrylate) brush has 2 to 9 ethoxy units in its side chain.

4. The temperature-responsive blood perfusion adsorption resin according to claim 1, characterized in that, The grafting rate of the poly(polyethylene glycol methyl ether methacrylate) brush is 5-25%, and the chain length is 10-100 nm.

5. A method for preparing the temperature-responsive blood perfusion adsorption resin according to any one of claims 1 to 4, characterized in that, Includes the following steps: S1, porous carrier spheres, acid-binding agent and initiator precursor are added to the first solvent and reacted to obtain activated spheres; S2, the activated spheres, polyethylene glycol methyl ether methacrylate monomer, catalyst and ligand are added to a second solvent to carry out a polymerization reaction to obtain the temperature-responsive blood perfusion adsorption resin.

6. The preparation method according to claim 5, characterized in that, The preparation process of the activated base spheres described in S1 is as follows: S11, after the porous carrier spheres are added to the first solvent and swollen for 1.5 to 2.5 hours, an acid-binding agent is added; S12, first add the initiator precursor dropwise under ice bath conditions, keep the temperature <5℃ until the dropwise addition is completed, then raise the temperature to 20~30℃, and react for 24±2 hours to obtain the crude activated base spheres; S13, the activated base spheres are obtained by washing and drying the crude activated base spheres.

7. The preparation method according to claim 5, characterized in that, The preparation process of the temperature-responsive blood perfusion adsorption resin described in S2 is as follows: S21, polyethylene glycol methyl ether methacrylate monomer is added to the second solvent, and nitrogen gas is introduced into the system to remove oxygen; S22, the catalyst and ligand are added to the system, and nitrogen is continued to be introduced to remove oxygen; S23, after adding the activated base spheres to the system and sealing it, the polymerization reaction was carried out at 20~30℃ for 2~24 hours to obtain the crude product of temperature-responsive blood perfusion adsorption resin; S24, the temperature-responsive blood perfusion adsorption resin crude product is obtained by washing and drying.

8. The preparation method according to claim 5, characterized in that, The mass ratio of the porous support spheres, the first solvent, the acid-binding agent, and the initiator precursor in S1 is 1:(10~15):(0.25~0.35):(0.4~0.5); the first solvent includes anhydrous dichloromethane, the acid-binding agent includes triethylamine, and the initiator precursor includes 4-(chloromethyl)benzoyl chloride.

9. The preparation method according to claim 5, characterized in that, The mass ratio of the activated spheres to polyethylene glycol methyl ether methacrylate monomer, catalyst, ligand, and second solvent in S2 is 1:(0.8~1.2):(0.01~0.03):(0.04~0.06):(8~10); the catalyst includes cuprous bromide, the ligand includes pentamethyldiethylenetriamine, and the second solvent includes a mixed solution of methanol and water.

10. A blood perfusion device, characterized in that, The hemoperfusion device contains the temperature-responsive hemoperfusion adsorption resin as described in any one of claims 1 to 4.

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