Fabrication,Functional Design And Application On Skin Regeneration Of Chitosan/Sodium Alginate Hydrogel

The skin is the body’s largest physical barrier,responsible for resisting the invasion of external viruses,so it is most vulnerable to various types of damage.Depending on the degree of skin damage,the repair of complex types of damage usually takes a long time in the two stages of hemostasis and anti-infection,which delays the process of tissue repair and results in difficult-to-heal tissue.In view of the above situation,it is very important to achieve wound closure of damaged tissue as soon as possible.Therefore,the gel is often loaded with a variety of growth factors to promote cell growth and tissue repair.In addition,many gel dressings suffer from infection problems and poor cell viability in long-term culture.In order to solve the above problems,this paper prepared a basic gel with both hemostasis and anti-infection based on chitosan(CS)/sodium alginate(SA)/ polyethylene glycol diacrylate(PEGDA).Two factors,fibroblast growth factor)and VE-cadherin(vascular endothelial cadherin),promote the co-culture of multiple skin cells,and are suitable for multiple types of skin lesions.The main work of this paper is as follows:(1)Construct a gel based on three ratios of CS/SA/PEGDA,containing pores inside,and possessing appropriate swelling,rheological and degradation properties.CS and SA were formed into gels by chemical cross-linking and electrostatic binding,and PEGDA was added to improve the rheological properties of the gels.The pore size of the gel after pore making is about 50-120 μm.The C6S4P100 component gel has more obvious infrared characteristic peaks,higher gel crosslinking degree,smaller internal pore size,higher rheological mechanical properties and slower degradation rate.The physicochemical properties of the composite gels with three ratios of CS/SA/PEGDA are suitable for subsequent biological experiments.(2)To explore the hemostasis and antibacterial ability of the composite gel with three ratios of CS/SA/PEGDA.It mainly detects the in vitro blood properties and in vivo hemostatic ability of the gel,as well as the antibacterial ability of the gel against Gram-negative bacteria and positive bacteria in vivo and in vitro.Experiments show that the gel has a certain hemostatic ability in in vitro and in vivo experiments.In terms of antibacterial,the in vitro antibacterial rate of the two bacteria reached more than 95 %,which has antibacterial effect.In vivo antibacterial experiments showed that the skin of animals infected with bacteria covered with gel dressings did not cause infection.The above results indicated that the gel had good hemostatic and antibacterial functions in vitro and in vivo,and provided theoretical support for subsequent experiments.(3)To explore the effect of three ratios of CS/SA/PEGDA composite gel on the growth behavior of SMC,L929 and EC skin cells.In this paper,EC,EPC(endothelial progenitor cells),fibroblast cells and SMC cells were cultured separately by culturing cells on the surface of the gel and encapsulating cells inside the gel to explore the culture method and gel ratio suitable for cell growth.The results show that the method of encapsulating cells with gel is better than that of culturing cells on the surface.Second,unlike cells growing on a two-dimensional plane,cells in the gel component can grow in layers,and most of them grow in clusters.(4)To explore the effect of functionalized modified composite gel on cell coculture growth.The growth factors bFGF and VE-cadherin were introduced to functionalize the gel,and the effect of the functionalized gel on the growth of two or three kinds of cells was explored.The results showed that the functionalized gel could support the cells to grow in a proliferative state for at least 12 days.When L929&EC and SMC&L929&EC were co-cultured with multiple cells,the cell viability could be increased several times,and the cell density was also significantly increased.The effect on multicellular growth activity was that the C8S2 P gel modified by one factor is better than the C8S2 P gel,and the C8S2 P gel modified by two factors has the best cytocompatibility.(5)To explore the repair of the functionalized composite gel on four skin injury models.In order to study the repair of the gel on different injury models,four injury types were constructed in this paper: skin incision wound,full-thickness skin excision wound,shallow scald,and deep scald.The results showed that incisional wounds were repaired in about 4 days,full-thickness skin excision was basically completed in about 8 days,shallow burns were repaired in about 14 days,and deep burns needed to be repaired in 24 days.In addition,when there is no necrotic tissue around the wound,C6S4P-F-V gel is selected for repair;when there is necrotic tissue around the wound,C8S2P-F-V gel is selected for repair.To sum up,this thesis constructed a composite gel based on CS/SA/PEGDA.By comparing the physical and chemical properties of the gel,the appropriate gel ratio was screened for blood,bacteria and cell experiments.Using the optimal gel ratio,the gel was functionalized with bFGF and VE-cadherin,and its effect on the co-culture growth of various skin cells was explored.Finally,animal experiments showed that C6S4P-FV component gel is suitable for repairing skin damage types without necrotic tissue around the mouth,and C8S2P-F-V component gel is suitable for repairing skin damage types with necrotic tissue around the mouth.This paper provides a gel dressing that is easy to prepare,easy to use and suitable for various repair types for complex skin repair.