Preparation And Properties Of Hydrogel Based Biological Adhesives

The ideal hydrogel bioadhesives should have the basic requirements of good biocompatibility,excellent antibacterial and adhesive properties.However,most hydrogels do not satisfy these conditions at the same time.Therefore,it is an urgent task to develop hydrogels that meet the requirements of biological adhesives.The design of this paper is based on the requirements of biological adhesives,starting from the selection of materials.Three kinds of materials with good biological compatibility have been selected to prepare hydrogels,they are chitosan(CS),poly(N-isopropyl acrylamide)(PNIPAM),and polyacrylamide(PAM).The essential properties of biomaterials such as cytotoxicity,adhesion and mechanical properties of hydrogels were studied.The main research content is as follows:1.Preparation of thermo-sensitive catechol modified chitosan(CS-pC)hydrogel with near-infrared controlled release function.CS-pC was synthesized by modifying CS with 3,4-dihydroxybenzoic acid.On this basis,the solution of CS-pC acetic acid aqueous solution was mixed with ?-glycerophosphate aqueous solution to form sol.CS-pC/?-GP hydrogel had non-cytotoxic and excellent antibacterial properties were obtained by heating the sol at a certain temperature.The critical peel strength of the hydrogel adhered to porcine skin was up to 4.9 kPa,which was 8 times higher than the critical peel strength of CS hydrogel(0.6 kPa).Furthermore,the CS-pC/?-GP/DH/AuNR hydrogel with near-infrared controlled release function was obtained by adding the drug doxicycline hydrochloride(DH)and near-infrared photo-thermal agent gold nanorods(AuNR)during the formation of CS-pC/?-GP/DH/AuNR sol.The photo-thermal experiment shows that the composite hydrogel has a good light rapid heating performance,and the loaded DH can be rapidly released under 808 nm near-infrared laser irradiation,with the release rate 6 times of that under no light.2.PNIPAM hydrogel containing N-vinylimidazole copolymer unit was prepared by y-ray radiation in one step.The experimental method of preparing PNIPAM hydrogel by radiation method was simpler than that of chemical method.First,N-isopropyl acrylamide,N,N'-methylene diacrylamide and N-vinylimidazole were dissolved in deionized water,and then PNIPAM hydrogel was prepared in one step byy-ray radiation.The results showed that the PNIPAM hydrogel prepared by radiation method was nontoxic and antibacterial.In addition,the hydrogel monomer prepared by radiation reaction is complete without residual monomer(monomer is toxic).The mechanical properties test showed that the hydrogel showed excellent mechanical properties,and the compression strength was up to 1.87 MPa.The critical stripping strength of the hydrogel on porcine skin after the introduction of N-vinylimidazole was up to 1.8 kPa,while the PNIPAM hydrogel without the introduction of N-vinylimidazole had no adhesion.3.Preparation of PAM hydrogel reinforced by PAA-b-PS microspheres of amphiphilic block copolymer.PAA-b-PS microsphere suspension was synthesized by'living' polymerization.Ethylene glycol dimethacrylate(EGDMA),acrylamide(AM),ammonium persulfate(APS),and N-vinylimidazole were added into the suspension system.The system is heated to form PAM hydrogel at a certain temperature.The results show that PAM hydrogel had good biocompatibility and antibacterial properties.EGDMA crosslinked PAA-b-PS microspheres as crosslinking points greatly enhanced the compression strength of PAM hydrogel(0.16 MPa).The critical peel strength of the hydrogel on porcine skin can reach 0.3 kPa due to the co-polymerization of N-vinylimidazole,while PAM hydrogel without N-vinylimidazole has no adhesion.These three kinds of hydrogels meet the requirements of the paper in terms of biocompatibility,antibacterial and adhesion properties.The simple operation and high repeatability of the experimental results provide a more specific way for the preparation of hydrogel bioadhesive.