Temperature-sensitive sustained-release medical adjuvant and preparation method thereof

Abstract

The application discloses a temperature-sensitive sustained-release medical auxiliary material and a preparation method thereof, and belongs to the technical field of medical auxiliary materials.The temperature-sensitive sustained-release medical auxiliary material according to the application contains the following components in percentage by mass: 1-2% w / v of acrylamidated hydroxyethyl chitosan, 5-15% w / v of polyethylene glycol diacrylate, 1-6% w / v of N-methyl acrylate caprolactam, 0.05-2% w / v of an initiator, 0.01-0.5% w / v of a crosslinking agent, and the balance of a PBS solution; the acrylamidated hydroxyethyl chitosan is chitosan modified by hydroxy and modified by ethyl; the N-methyl acrylate caprolactam monomer provided by the application effectively improves the temperature sensitivity of the temperature-sensitive polymer auxiliary material; the acrylamidated hydroxyethyl chitosan can reduce the swelling ratio and slow down the drug release; the polyethylene glycol diacrylate can be a crosslinking monomer of the temperature-sensitive polymer auxiliary material, and can simultaneously introduce an ether bond to improve the biocompatibility; and the three components are combined to prepare a temperature-sensitive sustained-release medical auxiliary material which has a low drug release rate and responds to the human body temperature.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of medical adjuvant, in particular to a temperature-sensitive sustained-release medical adjuvant and a preparation method thereof. BACKGROUND

[0002] Wound healing is a dynamic and complex process, and the microenvironment of the wound site plays an important role in it. As a commonly used material for wound healing, medical adjuvant can maintain a moist environment for the wound, accelerate wound healing, and prevent external wound infection. Hydrogel is a polymer with a three-dimensional network structure composed of hydrophilic segments, which has the advantages of high water content, good biocompatibility, and adjustable physicochemical properties, and has become a research hotspot in the field of wound adjuvant. Intelligent hydrogel adjuvant has attracted widespread attention due to its excellent environmental responsiveness. As a kind of intelligent polymer hydrogel, temperature-sensitive hydrogel can respond to small changes in the environment. When the temperature is lower than the gelation temperature, such as room temperature, it is in a flowable sol state. When the temperature is at the gelation temperature, such as body temperature, it quickly gels into a semi-solid gel, regulates drug release, and realizes time and space controllable on-demand drug delivery, which is an intelligent hydrogel adjuvant. The temperature-sensitive medical hydrogel applied to the wound should have antibacterial or anti-inflammatory properties, biocompatibility, temperature response sensitivity, and appropriate adhesion and mechanical properties. Natural polysaccharide chitosan has good biocompatibility and antibacterial properties, but its temperature-sensitive response characteristics are poor, and the prepared hydrogel is loose and porous, and the drug release rate is fast. SUMMARY

[0003] In order to overcome the deficiencies of the prior art, the present application provides a temperature-sensitive sustained-release medical adjuvant and a preparation method thereof. The temperature-sensitive sustained-release medical adjuvant is a hydrogel network copolymerized by N-methyl acrylate caprolactam (NVC), modified acrylated hydroxyethyl chitosan (EtCS) and polyethylene glycol diacrylate. N-methyl acrylate caprolactam (NVC) imparts excellent temperature sensitivity to the gel; the modification of ethyl on the hydroxyl group of chitosan appropriately increases the hydrophobicity and reduces the drug release rate; polyethylene glycol diacrylate is used as a crosslinking agent to introduce ether bonds and increase the biocompatibility of the polymer.

[0004] The present application aims to provide a temperature-sensitive sustained-release medical adjuvant and a preparation method thereof.

[0005] The present application is achieved by the following technical solutions:

[0006] A temperature-sensitive sustained-release medical adjuvant, which comprises the following components by mass in solution: acrylamidized hydroxyethyl chitosan 1-2% w / v, polyethylene glycol diacrylate 5-15% w / v, N-methyl acrylate caprolactam 1-6% w / v, initiator 0.05-2% w / v, crosslinking agent 0.01-0.5% w / v, and the balance is PBS solution.

[0007] In one specific embodiment, the method for preparing N-methyl acrylate caprolactam (NVC) comprises the following steps:

[0008] Under a nitrogen atmosphere, 3-bromo methyl acrylate, caprolactam, inorganic base and ligand Ruphos are placed in a dry container, catalyst Pd2(dba)3 is added, and the temperature is raised to 80-100°C. After stirring for 12-24 hours, the reaction is complete. The reaction mixture is cooled to room temperature, purified, and the product N-methyl acrylate caprolactam is obtained.

[0009] In one specific embodiment, the amount of 3-bromo methyl acrylate is 1-1.5 equivalents of caprolactam; the inorganic base is one of potassium phosphate or cesium carbonate; and the amount of ligand Ruphos is 0.1-0.5 wt% of caprolactam.

[0010] In one specific embodiment, the method for preparing acrylated hydroxyethyl chitosan (EtCS) comprises the following steps:

[0011] S1. Chitosan is dissolved in a 1% acetic acid solution, triethylamine is added to adjust the pH, phthalic anhydride is added, and the temperature is raised to react for 12 hours. After the reaction is complete, dialysis (MWCO 3500 Da, 2-3 days) is performed with deionized water, and freeze-drying is performed to obtain phthalated chitosan.

[0012] S2. Under a nitrogen atmosphere, anhydrous DMF is added to a 250 mL three-necked flask containing phthalated chitosan, and stirring is performed at room temperature to dissolve; dry inorganic base powder (6 equivalents per hydroxyl group) is added, stirring is performed for 0.5 hours to activate the hydroxyl group; halogenated alkane such as iodoethane is added, and the temperature is raised to react for 7 hours; after the reaction is complete, filtration is performed, the filtrate is poured into ice water (containing 1% acetic acid) to precipitate, centrifugation is performed to collect the solid, and ethanol is used for washing and purification; dialysis (MWCO 3500 Da, water / methanol mixed solvent) is performed, and freeze-drying is performed to obtain phthalated hydroxyethyl chitosan.

[0013] S3. 80% Hydrazine hydrate (excess), ethanol / water mixed solvent is added to the ethylated phthalated chitosan, and reaction is performed at 60°C; after the reaction is complete, dialysis purification is performed, and freeze-drying is performed to obtain hydroxyethyl chitosan.

[0014] S4. Under a nitrogen atmosphere, hydroxyethyl chitosan is dissolved in anhydrous THF, and stirring is performed in an ice bath for 30 minutes; a mixture of acryloyl chloride and triethylamine (0.8 equivalents) is slowly added dropwise, and reaction is performed at 0°C for 2 hours; after the reaction is complete, ice ethyl ether is poured into the reaction liquid, the precipitate is filtered, dialysis (MWCO 3500 Da) is performed, and freeze-drying is performed to obtain acrylamidated hydroxyethyl chitosan.

[0015] In one specific embodiment, the pH in step S1 is 4-6, the amount of phthalic anhydride is 1-1.5 equivalents of chitosan, and the temperature is 40-60°C.

[0016] In one specific embodiment, the inorganic base in step S2 is one of potassium hydroxide, potassium carbonate, cesium carbonate or potassium phosphate, the amount of the inorganic base is 3-6 equivalents of the hydroxyl groups contained in the phthalated chitosan, the haloalkane is one of methyl iodide or ethyl iodide or propyl iodide, the amount of the haloalkane is 1-1.1 equivalents of the hydroxyl groups contained in the phthalated chitosan, and the temperature is 40-60°C.

[0017] In one specific embodiment, the reaction time in step S3 is 24-48 hours.

[0018] In one specific embodiment, the amount of acryloyl chloride in step S4 is 0.8-1.2 equivalents of the hydroxyethyl chitosan, and the amount of triethylamine is 0.5-1 equivalent.

[0019] In one specific embodiment, the initiator is selected from ammonium persulfate (APS), and the crosslinking agent is selected from N,N,N',N'-tetramethyl ethylenediamine (TEMED).

[0020] Another object of the present application is to protect a preparation method of a temperature-sensitive sustained-release medical adjuvant, comprising the following steps:

[0021] S1. Preparation of a pre-gel solution: the specific steps are as follows: pass the acrylamidated hydroxyethyl chitosan powder through an 80-mesh sieve to remove agglomerated particles; dissolve the acrylamidated hydroxyethyl chitosan in a preheated PBS solution and magnetically stir until completely dissolved; add polyethylene glycol diacrylate to the solution and stir until uniform; then add N-methyl acrylamide caprolactam dissolved in a small amount of DMSO to the above solution, stir in the dark; add the initiator and stir, then add TEMED and mix quickly;

[0022] S2. Thermal initiation of polymerization: the specific steps are as follows,

[0023] Inject the pre-gel solution into a mold, in one specific embodiment, the mold is a silica gel cylindrical mold, and remove the bubbles by gently shaking; cover the sealing film and react in a 37°C water bath for 30-60 min;

[0024] S3. Post-treatment: the specific steps are as follows,

[0025] After the reaction is completed, the gelled product is washed with PBS for 3 times to remove the unreacted monomers, and then the hydrogel is immersed in a PBS solution containing 10% ethanol, and the water is changed every 12 hours for 72 hours to remove the organic solvent DMSO, TEMED and inorganic salt APS; the ethanol is removed by vacuum drying to obtain a dried gel sample, thereby obtaining the temperature-sensitive sustained-release medical adjuvant.

[0026] Advantages

[0027] The present application provides a temperature-sensitive sustained-release medical adjuvant and a preparation method thereof. The temperature-sensitive sustained-release medical adjuvant is prepared by dissolving acrylamidated hydroxyethyl chitosan, polyethylene glycol diacrylate and N-methyl acrylamide caprolactam in a PBS solution, and then free radical polymerization, cross-linking and purification under the condition of an initiator to form a hydrogel, thereby obtaining the temperature-sensitive sustained-release medical adjuvant. N-methyl acrylamide caprolactam (NVC) endows the gel with excellent temperature sensitivity, so that the hydrogel remains in a sol state at room temperature, and can present a semi-solidified gel when applied on a wound as an adjuvant, adhere to the skin and release drugs. The modification of alkyl such as ethyl on the hydroxyl group of chitosan appropriately increases the hydrophobicity, reduces the swelling performance and the pore size, thereby effectively reducing the drug release rate and prolonging the drug action time. Polyethylene glycol diacrylate acts as a cross-linking agent to promote the copolymerization of the three components, and simultaneously introduces an ether bond to increase the biocompatibility of the polymer for application on a living body. BRIEF DESCRIPTION OF DRAWINGS

[0028] Figure 1 Synthetic route of the temperature-sensitive medical adjuvant;

[0029] Figure 2 NMR spectrum of N-methyl acrylamide caprolactam;

[0030] Figure 3 Infrared spectra of pure chitosan, acrylamidated hydroxyethyl chitosan and the temperature-sensitive medical adjuvant polymer. DETAILED DESCRIPTION

[0031] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0032] In the embodiments, the experimental methods used are conventional methods if no special instructions are given, and the materials, reagents and the like used can be obtained from commercial channels if no special instructions are given.

[0033] The raw materials used in the examples and comparative examples will be described as follows.

[0034] Caprolactam: 99.5%, Cat. No. B02025199, purchased from Shanghai Annjei Chemical Co., Ltd;

[0035] 3-Bromomethyl acrylate: 95%, Cat. No. BD306828, purchased from Shanghai Biode Chemical Technology Co., Ltd;

[0036] Catalyst: Tris(dibenzylideneacetone)dipalladium(0) (Pd2(dba)3), 98%, Cat. No. BD21135, purchased from Shanghai Biode Chemical Technology Co., Ltd;

[0037] Ligand: 2-Dicyclohexylphosphino-2',6'-diisopropoxy-1,1'-biphenyl (Ruphos), 97%, Cat. No. BD74362, purchased from Shanghai Biode Chemical Technology Co., Ltd;

[0038] Chitosan: Degree of deacetylation ≥ 95%, MW 50000-60000, Cat. No. C766421, purchased from Shanghai Macklin Biochemical Technology Co., Ltd;

[0039] Phthalic anhydride: 99.7%, Cat. No. P816733, purchased from Shanghai Macklin Biochemical Technology Co., Ltd;

[0040] Acetic acid: 99.5%, Cat. No. A801295, purchased from Shanghai Macklin Biochemical Technology Co., Ltd;

[0041] Triethylamine: 99.5%, Cat. No. T818774, purchased from Shanghai Macklin Biochemical Technology Co., Ltd;

[0042] N,N-Dimethylformamide: 99.8%, Cat. No. N821474, purchased from Shanghai Macklin Biochemical Technology Co., Ltd;

[0043] Iodoethane: 99%, Cat. No. I811648, purchased from Shanghai Macklin Biochemical Technology Co., Ltd;

[0044] Hydrazine hydrate: Cat. No. C19671, purchased from Shanghai Annjei Chemical Co., Ltd;

[0045] Acryloyl chloride: 96%, Cat. No. A800376, purchased from Shanghai Macklin Biochemical Technology Co., Ltd;

[0046] Initiator: Ammonium persulfate, 99.99%, Shanghai Aldrich Biochemical Technology Co., Ltd;

[0047] N,N,N,N-Tetramethylethylenediamine (TEMED): 99%, Cat. No. N818999, purchased from Shanghai Macklin Biochemical Technology Co., Ltd;

[0048] PBS solution: pH 7.4, Cat. No. P787575, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.

[0049] Polyethylene glycol-based double-end crosslinking monomer: polyethylene glycol diacrylate (PEGDA); Mn 700, Cat. No. P816111, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.

[0050] Adriamycin (Adriamycin, DOX): 97%, Cat. No. A864033, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.

[0051] N-methyl acrylate caprolactam (NVC): self-made, the preparation method is as follows: under a nitrogen atmosphere, 3-methyl acrylate bromide (1.1 equivalents), caprolactam (1 equivalent), potassium phosphate (5 equivalents) and ligand Ruphos (0.1 wt%) are placed in a dry 10 mL Schlenk tube, and bubbled for 30 minutes; Pd2(dba)3 catalyst is added and bubbled for another 10 minutes, and then heated to 100°C; after stirring for 24 hours, the reaction is completed; the reaction mixture is cooled to room temperature, diluted with dichloromethane, filtered, and the filtrate is concentrated and purified by flash chromatography on a short silica gel column (dichloromethane / n-hexane) to obtain the product N-methyl acrylate caprolactam;

[0052] Acrylated hydroxyethyl chitosan (EtCS): self-made, the preparation method is as follows:

[0053] S1. Chitosan (1 g) is dissolved in 1% acetic acid solution (100 mL), and triethylamine is added to adjust the pH to 4-6; phthalic anhydride (1.5 equivalents, dissolved in a small amount of acetone) is added, and the reaction is carried out at 60°C for 12 hours; after the reaction is completed, dialysis (MWCO 3500 Da, 2-3 days) is carried out with deionized water, and freeze-drying is carried out to obtain phthalated chitosan;

[0054] S2. Under a nitrogen atmosphere, anhydrous DMF is added to a 250 mL three-necked flask containing phthalated chitosan, and stirred to dissolve at room temperature; dry potassium hydroxide powder (6 equivalents / hydroxyl) is added, and stirred for 0.5 hours to activate the hydroxyl groups; iodomethane (1.1 equivalents / hydroxyl) is added, and the reaction is carried out at 45°C for 7 hours; after the reaction is completed, filtration is carried out, and the filtrate is poured into ice water (containing 1% acetic acid) to precipitate, and centrifugation is carried out to collect the solid, which is washed with ethanol for purification; dialysis (MWCO 3500 Da, water / methanol mixed solvent) is carried out, and freeze-drying is carried out to obtain phthalated hydroxyethyl chitosan;

[0055] S3. Hydrazine hydrate (excess) and an ethanol / water mixed solvent are added to the ethylated phthalated chitosan, and refluxed for 4 hours; after the reaction is completed, dialysis purification is carried out, and freeze-drying is carried out to obtain hydroxyethyl chitosan;

[0056] S4. Under nitrogen atmosphere, hydroxyethyl chitosan (1 eq) was dissolved in anhydrous THF and stirred in ice bath for 30 min; a mixture of acryloyl chloride (1.1 eq) and triethylamine (0.8 eq) was added dropwise slowly at 0 °C and reacted for 2 h; after the reaction was completed, ice ethyl ether was poured into the reaction solution, the precipitate was filtered, dialyzed (MWCO 3500 Da), and lyophilized to obtain acrylamidated hydroxyethyl chitosan; the acrylamidation degree DS was 70%-90%, and the yield was between 85%-90%, and the results were as follows:

[0057] Table 1. Synthesis results of EtCS

[0058] Sample name Molar ratio Degree of substitution / % (DS) Yield / % EtCS-1 0.81 70 86 EtCS-2 0.96 85 89 EtCS-3 1.06 90 85

[0059] Examples and comparative examples

[0060] A temperature-sensitive sustained-release medical material: self-made, and the preparation method is as follows:

[0061] S1. Preparation of pre-gel solution: the specific steps are as follows: the acrylamidated hydroxyethyl chitosan powder is sieved through an 80-mesh sieve to remove agglomerated particles; acrylamidated hydroxyethyl chitosan (1.17% w / v) is dissolved in a preheated 86 mL PBS (37 °C) solution, and magnetically stirred for 2-4 h until completely dissolved; polyethylene glycol diacrylate (10% w / v) is added to the solution, and stirred for 30 min until uniform; N-methyl acrylamide caprolactam (2.75% w / v) dissolved in a small amount of DMSO is added to the above solution, and stirred in the dark for 20 min; first, APS (such as 0.05% w / v) is added and stirred for 5 min, and then TEMED (0.05% w / v) is added, and quickly mixed;

[0062] S2. Thermal initiation polymerization: the specific steps are as follows,

[0063] The pre-gel solution is injected into a silicone gel cylindrical mold, and the bubbles are removed by gently shaking; a sealing film is covered and reacted in a 37 °C water bath for 30-60 min;

[0064] S3. Post-treatment: the specific steps are as follows,

[0065] After the reaction is completed, the gel is washed with PBS for 3 times to remove unreacted monomers; then the hydrogel is immersed in a 10% ethanol-containing phosphate buffer PBS solution, and the water is changed every 12 h for 72 h to remove the organic solvents DMSO and TEMED and inorganic salt APS; vacuum drying is performed to remove ethanol, and PNVC-EtCS-PEGDA dry gel samples are obtained, i.e., the temperature-sensitive sustained-release medical material is obtained;

[0066] A temperature-sensitive drug-loaded hydrogel acrylamidated hydroxyethyl chitosan and polyethylene glycol diacrylate and N-methyl acrylamide caprolactam hydrogel (DOX-PNVC-EtCS-PEGDA): self-made, the preparation method is as follows:

[0067] The preparation method is different from the pure hydrogel in that 1g of a drug such as doxorubicin (DOX) is added to the PBS solution in S1 to prepare the hydrogel.

[0068] The component raw materials used in each embodiment and comparative example of the present application are commercially available raw materials unless otherwise specified, and the component raw materials used in each parallel experiment are the same.

[0069] Table 2 Temperature-sensitive sustained-release medical adjuvant (mass fraction, supplemented with PBS to 100g)

[0070]

[0071]

[0072] A temperature-sensitive sustained-release medical adjuvant prepared in the examples and comparative examples was subjected to the following performance tests, and the results are shown in the accompanying drawings and Table 2, respectively.

[0073] 1. Nuclear magnetic resonance spectrum: The synthesized N-methyl acrylamide caprolactam sample was dissolved in deuterated chloroform to prepare a solution with a concentration of 1.0wt%, and the nuclear magnetic spectrum of the sample was determined by a nuclear magnetic resonance hydrogen spectrometer, with a test condition of 400MHz, and the results are shown in Figure 2 .

[0074] 2. Infrared spectrum: N-methyl acrylamide caprolactam and acrylamidated hydroxyethyl chitosan and dry gel after polymerization were mixed with potassium bromide at a ratio of 1:50 to prepare a tablet. This test used an Avatar380 spectrometer, and the sample was pressed into a tablet with potassium bromide. Before testing, the blank background was scanned, and then the tablet sample was placed for testing. The scanning range was 500-4000cm -1 , and the results are shown in Figure 3 .

[0075] 3. Rheological test: The rheological properties of the hydrogel were tested by a rotational rheometer, and the rotational rheometer used was model RS6000. The hydrogel sample was placed between parallel plates with a diameter of 20mm, and the plate spacing was adjusted to 1.0mm. First, the sample was dissolved in PBS buffer to prepare a PNVC-EtCS-PDGA solution (5wt%). The relationship between the storage modulus (G') and the loss modulus (G") and the temperature change (5-50℃) was determined, and the test condition was a frequency of 1Hz and a strain of 0.1%. The intersection of the G' and G" curves was T gel .

[0076] 4. Swelling property: Swelling property is related to crosslinking degree and hydrophobicity / hydrophilicity, suitable swelling property is beneficial to drug loading and application in vivo. The swelling property of hydrogel was determined by weighing method, first, a certain mass (Wd) of PNVC-EtCS-PDGA dry gel was weighed, then it was immersed in PBS solution, placed in 37°C environment for a period of time, then taken out, the PBS solution on the surface of the gel was removed and weighed (Wt), the swelling ratio (SR) of the hydrogel was calculated according to the following formula:

[0077]

[0078] 5. Encapsulation efficiency (EE%) test: The instrument type TDZ4-WS instrument table low-speed automatic balance centrifuge was used to centrifuge the prepared drug-loaded hydrogel (3,000 rpm, 15 min), the supernatant was collected, and the free drug concentration C was tested by HPLC free , combined with the initial drug concentration Co to obtain. The encapsulation efficiency was calculated by the following formula:

[0079]

[0080] 6. Drug release performance test: UV-Vis was used to test the in vitro drug release performance of hydrogel to doxorubicin. The drug hydrogel (5.0wt%) was dissolved in 30mL PBS buffer at 4°C, and the DOX-PNVC-EtCS-PEGDA drug-loaded gel was prepared after dissolution, and was placed in a constant temperature water bath shaker at 37°C, and the shaking speed was 20r / min. According to the predetermined time, 1mL PBS solution was taken in a small test tube, 2mL fresh PBS solution was added, and the same volume of fresh PBS solution was added. Finally, the drug concentration in 1mL PBS solution was measured by HPLC, and the total concentration in 30mL PBS solution was calculated, and the release rate of the drug on the 5th day was tested. The cumulative drug release rate (Ar) can be calculated by the following formula:

[0081]

[0082] Where V0 is the total volume of PBS; c t is the concentration of doxorubicin in PBS measured at a certain time point; V is the volume of PBS taken each time; m is the initial drug loading amount of DOX-PNVC-EtCS-PEGDA hydrogel.

[0083] Table 3 Test results of the performance of temperature-sensitive sustained-release hydrogel

[0084]

[0085] From the attached Figure 2The integral number of hydrogen spectrum is consistent with the number of hydrogen in the molecule, and the displacement of each hydrogen atom in the spectrum is consistent with the chemical environment, indicating that the target compound N-methyl acrylate caprolactam is successfully synthesized.

[0086] From the attached Figure 3 It can be seen that in the spectrum, the peak value appears at 1720-1755cm -1 The stretching vibration of C=O belonging to ester carbonyl and amide carbonyl appears at 1640-1680cm -1 Belonging to C=C vibration. In the spectrum of modified chitosan, the peak value appears at 1750cm -1 The stretching vibration of C=O belonging to amide group appears at 1680cm -1 The stretching vibration of C=C double bond belonging to acrylate appears at 1596cm -1 The stretching vibration of amino group disappears, indicating that the acrylate is successfully introduced into the amino group of chitosan; at the same time, the peak value appears at 2972-2872cm -1 The new absorption peak of methyl and methylene belonging to the introduced ethyl indicates that the hydroxyl group is successfully replaced by ethyl. In the spectrum of hydrogel, the peak value appears at 1640-1680cm -1 The peak belonging to C=C vibration disappears, and the characteristic groups of the three monomers are possessed, proving that the PNVC-EtCS-PEGDA polymer has been successfully copolymerized to prepare the hydrogel.

[0087] As can be seen from Table 3, with the increase of crosslinking degree, T gel shows a downward trend, indicating that PNVC-EtCS-PEGDA has temperature sensitivity, and the temperature in Example 4 is close to the temperature of human skin, which will gel in situ when applied to human skin, forming a wound protection layer, suitable for biomedical applications; when there is no temperature-sensitive monomer, as shown in Comparative Example 2, the hydrogel shows almost no temperature sensitivity, and due to the high crosslinking density, the drug is difficult to release completely.

[0088] As can be seen from Table 3, the encapsulation efficiency of the prepared hydrogel is between 41-97%, and for the drug-loaded hydrogel with high crosslinking degree, Examples 4 and 5 are more than 80%, indicating that the prepared hydrogel is suitable for drug release carriers.

[0089] As can be seen from Table 3, the release time of doxorubicin drug can reach 5 days, and when reaching equilibrium, the release rate is generally more than 65%, indicating that the PNVC-EtCS-PEGDA hydrogel has the effect of slowing down the release of the drug, and is an excellent temperature-sensitive drug release carrier.

[0090] The preferred embodiments of the application disclosed above are only to facilitate the elucidation of the application. The preferred embodiments do not describe all the details of the application and limit the application to the specific embodiments described. Obviously, many modifications and variations can be made in light of the teachings above. The description is chosen and described in order to best explain the principles of the application and its practical application to thereby enable others skilled in the art to best utilize the application and get the best results from the application. The application is only limited by the claims and their full scope and equivalents.

Claims

1. A temperature-sensitive sustained-release medical adjuvant, characterized by, By mass percentage, it comprises the following components: acrylamidated hydroxyethyl chitosan 1-2% w / v, polyethylene glycol diacrylate 5-15% w / v, N-methyl acrylamide caprolactam 1-6% w / v, initiator 0.05-2% w / v, crosslinking agent 0.01-0.5% w / v, and the rest is PBS solution; The preparation method of the N-methyl acrylamide caprolactam comprises the following steps: Under a nitrogen atmosphere, 3-bromomethyl acrylate, caprolactam, inorganic base and ligand Ruphos are placed in a dry container, catalyst Pd2(dba)3 is added, and the temperature is raised to 80-100 ℃, and after stirring for 12-24 hours, the reaction is completed; the reaction mixture is cooled to room temperature, purified to obtain the product N-methyl acrylamide caprolactam; The preparation method of the acrylamidated hydroxyethyl chitosan comprises the following steps: S1. Dissolve chitosan in acetic acid solution, add triethylamine to adjust the pH value to 4-6; add phthalic anhydride, and react at elevated temperature for 10-20 hours; after the reaction is completed, dialyze with deionized water, freeze-dry to obtain phthaloylated chitosan; S2. Under a nitrogen atmosphere, add anhydrous DMF to the phthaloylated chitosan, and stir to dissolve at room temperature; add 4-8 equivalents of dry inorganic base powder to the hydroxyl group of the phthaloylated chitosan, and stir to activate the hydroxyl group; add halogenated alkane, and react at elevated temperature for 5-10 hours; after the reaction is completed, filter, pour the filtrate into ice water containing acetic acid to precipitate, centrifuge to collect the solid, and purify by washing with ethanol; dialyze, freeze-dry to obtain phthaloylated hydroxyethyl chitosan; S3. Add excess hydrazine hydrate and ethanol / water mixed solvent to the phthaloylated hydroxyethyl chitosan, and react at 60-75 ℃; after the reaction is completed, dialyze and purify, freeze-dry to obtain hydroxyethyl chitosan; S4. Under a nitrogen atmosphere, dissolve the hydroxyethyl chitosan in anhydrous THF, and stir in an ice bath; slowly add a mixture of acryloyl chloride and triethylamine, and react at 0-5°C for 2 hours; after the reaction is completed, pour ice ether into the reaction solution, filter the precipitate, dialyze, and freeze-dry to obtain acrylamidated hydroxyethyl chitosan.

2. The thermosensitive sustained-release medical excipient as described in claim 1, characterized in that, In the preparation method of the N-methyl acrylamide caprolactam, the amount of 3-bromomethyl acrylate is 1-1.5 equivalents of caprolactam; the inorganic base is one of potassium phosphate or cesium carbonate; and the amount of ligand Ruphos is 0.1-0.5 wt% of caprolactam.

3. The thermosensitive sustained-release medical excipient as described in claim 1, characterized in that, In step S1, the amount of phthalic anhydride is 1-1.5 equivalents of chitosan, and the reaction temperature is 40-60 ℃.

4. The thermosensitive sustained-release medical excipient as described in claim 1, characterized in that, In step S2, the inorganic base is selected from one or more of potassium hydroxide, potassium carbonate, cesium carbonate and potassium phosphate, the amount of the inorganic base is 3-6 equivalents of the hydroxyl group contained in the phthaloylated chitosan, the halogenated alkane is selected from one or more of methyl iodide, ethyl iodide and propyl iodide, the amount of the halogenated alkane is 1-1.1 equivalents of the hydroxyl group contained in the phthaloylated chitosan, and the reaction temperature is 40-60 ℃.

5. A temperature-sensitive sustained-release medical adjuvant according to claim 1, wherein the hydrophilic polymer is polyethylene glycol. The reaction time in step S3 is 24-48 hours; the acryloyl chloride dosage in step S4 is 0.8-1.2 equivalents of hydroxyethyl chitosan, and the triethylamine dosage is 0.5-1 equivalent.

6. A temperature-sensitive sustained-release medical adjuvant according to claim 1, wherein the hydrophilic polymer is polyethylene glycol. The initiator is selected from ammonium persulfate; the crosslinking agent is selected from N,N,N',N'-tetramethyl ethylenediamine.

7. A method for preparing a temperature-sensitive sustained-release medical adjuvant according to any one of claims 1 to 6, characterized in that, The method comprises the following steps: S1. Pre-gel solution preparation: the specific steps are as follows, the acrylamidated hydroxyethyl chitosan powder is sieved through an 80-mesh screen to remove agglomerated particles; the acrylamidated hydroxyethyl chitosan is dissolved in a preheated PBS solution and magnetically stirred until completely dissolved; polyethylene glycol diacrylate is added to the solution and stirred uniformly; N-methyl acrylate caprolactam dissolved in a small amount of DMSO is added to the above solution and stirred in the dark; the initiator is added, and then the crosslinking agent is added and quickly mixed; S2. Thermal initiation of polymerization: the specific steps are as follows, The pre-gel solution is injected into a mold, and the mold is gently shaken to remove air bubbles; a sealing film is covered, and the reaction is carried out in a 37 °C water bath for 30-60 min; S3. Post-treatment: the specific steps are as follows, After the reaction is completed, the gel is rinsed with PBS to remove unreacted monomers; then the hydrogel is immersed in a 10% ethanol-containing phosphate buffer PBS solution, and a dry gel sample is obtained after purification to prepare a temperature-sensitive sustained-release medical adjuvant.

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