Preparation And Performance Evaluation Of Two Kinds Of Glycyrrhiza Polysaccharide Hydrogels

Chronic skin ulcers have become a difficult problem in clinical treatment due to their complex etiology,long course of disease and high recurrence rate.It needs to be combined with debridement and drainage,antibiotics,growth factors,therapeutic cells,traditional Chinese medicine ingredients and other factors.Conventional preparations are difficult to load so many active ingredients.Hydrogel dressings can absorb wound exudates,support cell adhesion and migration,and thus have potential applications in chronic skin ulcers.Chitosan and sodium alginate have been used in the preparation of hydrogel dressings for their good biocompatibility and biodegradability.However,the hydrogels prepared by cross-linking chitosan and sodium alginate alone have single biological activity,glycyrrhiza polysaccharide has good immune regulation,anti-inflammatory and anti-bacterial activities.If the composite hydrogels can be prepared with glycyrrhiza polysaccharide and the above materials,it would contibute to chronic ulcer healing.In this research,the chitosan-glycyrrhiza polysaccharide?CS/GP?hydrogel and the sodium alginate/glycyrrhiza polysaccharide?Alg/GP?hydrogel was prepared and characterized.At first,glycyrrhiza polysaccharide was extracted.Then,the glycyrrhiza polysaccharide was mixed with chitosan and sodium alginate respectively,and two kinds of hydrogels were prepared by using genipin and Ca²⁺as crosslinkers respectively.The prepared hydrogels were characterized by fourier transform infrared spectroscopy,scanning electron microscopy,swelling ratio text,in vitro degradation text and rheology experiment.The results show that CS-GP hydrogel has excellent swelling performance,the swelling ratio is 1035.42%-1761.76%;the mechanical strength is 34-783Pa;the highest degradation rate in 28 days is 78.86%.In addition,the hydrogel showed a strong inhibitory effect on Escherichia coli and a relatively weak inhibitory effect on Staphylococcus aureus;It can be clearly seen from the results of scanning electron microscopy that the CS/GP hydrogel has a three-dimensional network internal structure,the size and density of the mesh can be changed by adding an appropriate concentration of glycyrrhiza polysaccharide.According to the results of cytocompatibility experiment,it can be concluded that the addition of glycyrrhiza polysaccharide can increase cell compatibility and even exhibit certain bone marrow mesenchymal stem cells?BMSC?proliferation activity at low cross-linking agent concentration.It can be seen from the swelling results that the Alg/GP hydrogel has an excellent swelling performance.In the buffer solution of pH7.4,the swelling ratio of the hydrogel is 616.51%-978.93%;The mechanical strength of the hydrogel is 92³82Pa;The degradation rate is 81.42%-93.61%,the addition of glycyrrhiza polysaccharide accelerated the degradation rate of Alg/GP hydrogel to some extent.It can be seen from the results of in vitro release that the addition of glycyrrhiza polysaccharide increases the cumulative release of gentamicin sulfate,the rate of release can be altered by adjusting the concentration of the glycyrrhiza polysaccharide.In summary,this study demonstrates that the addition of glycyrrhiza polysaccharides increasing the cell compatibility of genipin-crosslinked chitosan hydrogel and even shows certain BMSC proliferation promoting activity,increasing the antibacterial activity of the hydrogel.The internal structure of Ca²⁺cross-linked sodium alginate hydrogel has been changed with the addition of glycyrrhiza polysaccharides,which accelerates the degradation rate and increases the vitro drug release of the hydrogel to some extent.The two kinds of hydrogels have great potential for the treatment of chronic skin ulcers.