| Hydrogels,which are polymeric materials with hydrophilic three-dimensional structures,have been developed for a variety of applications,such as tissue engineering,drug delivery and release and medical diagnostics.Injectable photopolymerizable hydrogels have the advantage of in situ photopolymerization,and the biodegradable hydrogels are also importance in many applications.In this thesis,an injectable,photopolymerizable and biodegradable acrylate-terminated poly(ethylene glycol)-co-poly(xylitol sebacate)hydrogel(PEXS-A)was successfully synthesized from poly(ethylene glycol)(PEG),azelaic acid,xylitol and acryloyl chloride.The main research work and research results are as follows:(1)In order to explore the PEXS-A synthetic route,we studied the prepolymer purification method,PEG monomer weight percentage,acylation reagent selection and dosage and prepolymer dialysis time in the synthesis process.The poly(ethylene glycol)-poly(xylitol sebacate)prepolymer(PEXS)prepolymer purified by N,N-dimethylformamide(DMF)dissolving the prepolymer and then extracted with ice ethanol was purified.The results showed that the PEXS prepolymer with good water solubility obtained when the monomer PEG weight percentage is 60%.When the acylating agent acryloyl chloride increased,the acylation rate of the synthesized PEXS-A material was significantly reduced.The cytotoxicity of PEXS-3A hydrogelwas no significant difference to to positive control material PDLLA when the dialysis time of the PEXS-3A prepolymer reach 48 h.(2)In order to explore the performance of hydrogels formed by different acylation rates of PEXS-A materials,we synthesized three different acylation rates with xylitol: acryloyl chloride of 1:1,1:2 and 1:3,respectively.The photopolymerization time,physical properties,mechanical properties,degradation properties and microstructure of PEXS-2A,PEXS-3A and PEXS-4A hydrogels were characterized.The results showed that 25% wt/v PEXS-3A and PEXS-4A prepolymer can form hydrogel within 1 min.The equilibrium water content of the three hydrogels all about 90% and both have interconnected porous structures,which can provide conditions for the exchange of nutrients and metabolic wastes.The degradation rate of hydrogel decreases with the increase of acylation rate of PEXS-A prepolymer and the degradation accelerated in esterase containing solution.The Young’s modulus of three hydrogels increased with the increase of acylation rate of PEXS-A prepolymer and PEXS-3A hydrogel has the highest maximum strain and stress.The Young’s modulus of PEXS-A hydrogels are between 11 to 163 kPa which are suitable for a variety of tissue regeneration.(3)In order to explore the application of PEXS-A hydrogel material in tissue engineering,the experimental study of the hydrogel material as drug sustained release carrier and 3D printed tissue engineering scaffold were carried out.We first determined cytotoxicity of the three PEXS-A materials,the results showed that the cell viability of PEXS-3A and PEXS-4A hydrogel were relatively high.PEXS-3A hydrogel has better mechanical properties compared to PEXS-4A hydrogel,so we chose PEXS-3A for further study.The results of PEXS-3A hydrogel encapsulated mouse embryonic fibroblasts(NIH-3T3)showed that the cells in PEXS-3A hydrogel had 97.91 ± 0.13% and 93.76 ± 0.51% cell viability after 2 and 7 days,respectively.The number of cells at day 7 was 1.66 ± 0.04 times of day 2 indicating that PEXS-3A hydrogel scaffold has a microenvironment suitable for cell growth and proliferation.The results of PEXS-3A hydrogel as a drug release carrier showed that the bovine serum(BSA)release curve is approximately straight from 1 to 21 days indicating that the PEXS-3A hydrogel has a drug sustained release function.The PEXS-3A hydrogel was also studied as a 3D printing bio-ink printed by extrusion printing to fabricate a three-dimensional structure. |
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