| Gelatin extracted from animal skin has unique biomimetic properties and biological activity because of its natural spatial conformation and composition,it makes the research based on gelatin become one of the hot spots in biomedical materials.Biological adhesives achieves the hemostasis effect by adhesive and sealing the wound,which possess a good biocompatibility at the same time.At present,most of the hydrogel adhesives on the market are only suitable for the adhesive under dry conditions,but the adhesive strength is relatively low in the wet physiological environment,which limits the practical application of biological adhesives in the wet environment.In this thesis,the composition and structure of biomimetic extracellular matrix(ECM)were simulated.Using gelatin and hyaluronic acid as the main raw materials,a functional hydrogel adhesive based on gelatin with three-dimensional network structure was constructed,which could be applied in wet environment.And the structure,adhesion property and hemostasis property were analyzed and studied.The main research contents include:(1)Preparation and characterization of gelatin-dopamine bonding hydrogel(Gel-DA).Gel-DA was prepared by introducing dopamine(DA)into gelatin molecules through biological crosslinking agent-genipin(GP).The grafting rate of DA was determined by UV-Spectrometer(UV).The structure of Gel-DA hydrogel materials was characterized by Fourier transform infrared spectroscopy(FTIR)and X-ray photoelectron spectroscopy(XPS).The effect of the amount of DA on the adhesive strength of hydrogel was investigated.And the surface morphology,hydrophilic properties,mechanical properties and cytotoxicity of the Gel-DA hydrogel were characterized.The results showed that the optimal preparation conditions were as follows:the dosage of GP was 3%(in term of the mass of Gel),the dosage of DA was 12.5%(in term of the mass of Gel),and the mass fraction of hydrogel system was 10%(in term of the mass solvent).Gel-DA hydrogel prepared under these conditions had a compact three-dimensional porous network structure.The wet adhesive strength was(336±25)KPa which was more 119.6%than that of Gel,and the weight bearing of biological tissue could reach 1500 N,which was more 200%than that of Gel.The results of hydrophilic properties and cytotoxicity tests showed that Gel-DA had good hydrophilicity and biocompatibility,and the WCA was(76.2±3.6)°.Gel-DA could significantly promote the growth and proliferation of cell adhesion,which showed no cytotoxicity.(2)Preparation and characterization of hyaluronic acid/dopamine-gelatin bonding hydrogel(HI/Gel-DA).In order to further improve the mechanical properties of Gel-DA,HI/Gel-DA was constructed by grafting hyaluronic acid(HI)into Gel-DA by double injection method.The chemical structure of HI was characterized by 1H-NMR,and the surface groups of HI/Gel-DA hydrogel were analyzed by XPS and so on,which proved that the modification was successful.The elastic modulus(G’)of hydrogels were measured by dynamic rheometer,and the influence of the content ratio of HI components on the mechanical properties of the hydrogel was systematically studied.When the amount of HI was 8%(in term of the mass of Gel-DA),the reaction temperature was 37℃,and the reaction time was 12 h,the gelation time could be reduced to 56 s,and G’ could reach a maximum of 847.6 Pa.The surface morphology,hydrophilic properties and cytotoxicity of HI/Gel-DA hydrogel were characterized and tested.The results showed that the HI/Gel-DA hydrogel possessed good hydrophilicity and biocompatibility,and the contact Angle was(61.2±2.6)°.HI/Gel-DA could significantly promote the growth and proliferation of cell adhesion,which showed no cytotoxicity.(3)Preparation and characterization of Gelatin-based composite hemostatic hydrogel adhesive(HLC-β-ODAP-HI/Gel-DA).The HI/Gel-DA was physically mixed with the hemostatic component of traditional Chinese medicine notoginseng(β-ODAP)and the Human like collagen(HLC)which can promote tissue repair.The influence of different crosslinking methods on the thermal stability of hydrogel materials was systematically studied,and it was proved that the thermal response and thermal decomposition resistance of HLC-OPAP-HI/Gel-DA were significantly higher than those of Gel,Gel-DA and HI/Gel-DA,and the thermal weight loss process of the three was basically the same.Then,the hydrophilic properties,mechanical properties and cytotoxicity of the hydrogel were characterized,proving that HLC-β-ODAP-HI/Gel-DA hydrogel had excellent hydrophilic properties,mechanical properties,biocompatibility and other properties,which could be used as a potential tissue adhesive for clinical hemostasis.(4)Hemostatic properties and evaluation of gelatin-based functional hemostatic materials in vivo.The hemostasis performance of Gel-DA,HI/Gel-DA and HLC-ODA-HI/Gel-DA in vivo was evaluated by using the rat liver wound as the hemostasis model,the bleeding time and amount as the evaluation indexes.The hemostasis time was 108 s.The macroscopical effects of the above materials on the repair of skin defects in rats were studied by histology(HE,Masson)in the experimental model of rat back skin injury.The healing rate reached about 85%after 12 days.Immunohistochemical method was used to investigate the expression level of vascularization in endothelial skin tissue after repair.The functional advantages of three kinds of gelatin-based functional hemostatic materials in promoting tissue regeneration and repair were verified,which laid a theoretical and practical foundation for the construction of a new generation of gelatin-based biomedical materials based on gelatin. |
