Preparation And Properties Of Catechol-functionalized Chitosan/oyster Peptide Thermosensitive Hydrogel

Trauma is the most common disease in modern society and has a high incidence rate and disability rate.So far,various causes of bleeding and skin trauma still seriously threaten human health and life quality.China is rich in marine biological resources.Developing marine biological resources as new biomedical materials is an important approach to promote the rapid development of marine economy,which has great scientific significance,economic value and social benefits.In this paper,catechol functionalized chitosan(CS-C)was synthesized with chitosan(CS)as the starting materials.And then the thermosensitive hydrogels with hemostatic and wound healing efficacies were prepared by the combination of beta glycerin phosphate(?-GP)as a thermosensitive agent and marine active peptide.The main contents and results were as follows:1.Though coupling reaction,3,4-dihydroxyphenylpropionic acid(HCA)was grafted onto the main chain of CS to synthesize catechol functionalized chitosan(CS-C).The chemical structure of CS-C was characterized by UV,IR and NMR.The grafting rate of CS-C was 17.3%.The water solubility,thermal stability and antioxidant capacity of CS-C were studied.The results showed that the water solubility of CS-C was more than 5 g/100 m L,and the thermal stability was good.The DPPH radical scavenging rate was 92.8% when CS-C concentration was 35 ?g/m L,and the hydroxyl radical scavenging rate was 97.4% when CS-C concentration was1.5 mg/m L.The results of cell proliferation,apoptosis and hemolysis showed that CS-C had no cytotoxicity,and the hemolysis ratio was lower than that of the national standard,indicating good biocompatibility.2.The CS-C/?-GP thermosensitive hydrogels were fabrictaed and characterized.Studies showed that the mixture of CS-C(2%)and ?-GP(30%)with a volume ratio of8:2 gelatinized with 16 min at 37 ?.SEM results showed that the freeze-driedhydrogels showed a porous network structure,which was conducive to free passage of water and small molecule drugs,and could be used for hemostasis,wound healing and drug release.3.The oyster peptide(OP)was analyzed and chitosan/Oyster peptide microspheres(CSMO)were prepared by emulsification and crosslinking.The results showed that 95.48% of OP components had molecular weight below 1000 Da,possessing good water solubility.The prepared CSMO was spherical and the particle size ranged from 1 to 10 ?m.The encapsulation rate was 72.8% and the OP loading rate was 11.9%.,and the sustained-release effect of OP was good.4.The physical properties of thermosensitive hydrogels were tested and their effects on cell biology were studied.The results showed that CS-C/?-GP,CS-C/OP/?-GP and CS-C/CSMO/?-GP hydrogels had porous structure with uniform pore size,and the water absorption rate was above 550%,which could maintain the moist environment of wound.The results of cell viability and apoptosis showed that the three hydrogels had no cytotoxicity on L929 cells.The cell migration rates of CS-C/CSMO/?-GP and CS-C/OP/?-GP within 48 h were above 90%,which were significantly different from that of the blank control group,indicating that the hydrogels had the effect of promoting L929 cell migration.Under the concentration of1000 ?g/m L,the hemolysis rate of the hydrogels was lower than 5%,indicating that the hydrogel materials were harmless.5.The effects of hydrogels on hemostasis and wound repair were studied by establishing hemostasis and skin wound repair models.The results of whole blood coagulation index,coagulation time,platelet adhesion and erythrocyte adsorption showed that the hydrogels could promote effectively coagulation.Liver and tail bleeding models in mice showed that the hydrogels could accelerate hemostasis,which was comparable to that of commercial gelatin sponge.In the skin wound healing experiments,the pathological changes of the skin were observed,the pathological changes of the skin were observed,the contents of total protein,TNF-?and IL-6 in the tissues were detected,and the expression of Ki-67 and VEGF was analyzed by immunohistochemistry.The results showed that the hydrogels could reduce the accumulation of inflammatory cells in wound wounds,accelerate the generation of collagen fibers and new vessels,promote the synthesis of total protein in granulation tissue,up-regulate the expression of Ki-67 and VEGF in the wound surface,and accelerating wound healing.