Applied And Basic Study On Novel And Antifouling Hydrogel For Diabetic Ulcers

Diabetes mellitus, as a life-long condition which leads to a great deal of significant complications, has a growing epidemic in all the world, both developed and underdeveloped nations due to the improvement of living standards and lifestyles changing. The diabetic foot ulcer has been a well-known refractory disease with poor prognosis and could lead to gangrene and amputation, affecting the quality of life of patients and subjective well-being seriously. To solve this problem, we design and synthesize a novel hydrogel aimed at promoting the ulcer healing effectively based on the microclimate and extracellular matrix of intractable diabetic ulcer. We had used dextran and chitosan to mimicking the extracellular matrix.Here, we designed and synthesized a series of new hydrogel(CSDM) with and ideal three-dimensional network on the basic of thiolated chitosan and maleic acid-grafted dextran by the Michael addition reaction. The fabrication of CSDM hydrogel was easily available for the mild preparation conditions without any toxic catalyst and initiating agent, making it good cytocompatibility and to be appropriate for biological applications. We got five kinds of CSDM hydrogel by adjusting the molar ratio of thiol group and double bond. CSDM hydrogel with the typical porous structure and ideal three-dimensional network observed by Scanning electron microscope showed a rapid increase in equilibrium of swelling, which was up to 900% after 30 min incubation, making it a potential platform scaffold with controlled drug delivery. Importantly, the viability of NIH 3T3 cells was more than 80% after treatment with CSDM hydrogel(? 4 mg/mL) for 24 h and 48 h measured by MTT assay, displaying good cytocompatibility. For all of the CSDM hydrogels, their G' were greater than G" with the increase in the angular frequency of 0.1 rad/s to 100 rad/s indicating the stable formation of hydrogel. Furthermore, the stable physical properties made it could be moved around normally.Moreover, to conquer the problems of traditional wound dressings' easy adhesion, easy to damage nascent epithelial tissue during dressing changes causing bleeding problems worse, we made the optimization of material proportion to make it antifouling. Antifouling hydrogel could prevent bacterial and cell adhesion effectively. The adhesion of bacteria and cells to hydrogel was detected by Laser scanning confocal microscope and Scanning electron microscope. Compared with normal hydrogel, the adhesion of bacteria and cells to hydrogel surface and inside reduced greatly both in 400 and 2000 magnification, suggesting that the hydrogel could resistant to infection and do not hurt wound tissue. Taking into account the lack of growth factor in ulcer microenvironment, the in vivo study of bFGF-loaded antifouling hydrogel promoting diabetes mellitus SD rats wound healing was carried out. Four full-thickness skin defect wounds with diameter of 1.2 cm had been made to the SD rats. The experiment was divided into four groups, namely hydrogel group, hydrogel + Basic fibroblast growth factor(bFGF) group, bFGF group and normal saline group, respectively. By comparing the wound healing using T test, tissue morphology and immunohistochemical results of Proliferating cell nuclear antigen and Vascular endothelial growth factor between four groups, we found that the wound of hydrogel + bFGF group began to reduce significantly as early as the 5th day, and be healed completely in 13 th day firstly. Taken together, we found that bFGF-loaded hydrogel could Accelerate wound repair by regulating growth factor, forming wound anti-infection protective layer and providing wet environment for cell growth. Hence, the functional CSDM hydrogel provided a new way for the treatment of refractory diabetic ulcers and could be potential wound dressing for clinical application.