Preparation And Properties Studies On A Novel Cross-Linked Chondroitin Sulfate Hydrogel

Objective: Chondroitin Sulfate(CS)is a naturally sourced macromolecular polysaccharide that is one of the key substances in regulating skin p Hysiology.In this study,CS was structural modified,chemically cross-linked to prepare an injectable hydrogel for skin tissue filling or cell therapy,and to explore the application prospect of CS hydrogel.Methods: CS was used as raw material to obtain the structural modification of the aldehyde chondroitin sulfate CS-CHO and the amino-chondroitin sulfate CS-ADH.The modification degree was measured by the residual iodine method and the direct titration method,respectively.Two precursors,CS-CHO and CSADH,can be used to prepare hydrogels by means of Schiff base chemical crosslinking.Three kinds of hydrogels with different crosslinking degrees were prepared with volume ratios of 2:1,1:1 and 1:2.According to physical and chemical properties and biological evaluation,the optimal performance ratio of hydrogels was selected.Firstly,the structure of CS,CS-ADH,CS-CHO and CS hydrogels was characterized by Fourier infrared spectrometer,and the morp Hology of three proportional hydrogels was characterized by scanning electron microscopy.The mechanical strength of hydrogels was detected by rotating rheometer,and the water binding capacity of hydrogels was evaluated by water content.The reversible binding property of Schiff base bond was verified by self-healing experiment of hydrogel.In addition,the biocompatibility of hydrogels was also tested and analyzed.In vitro,the biocompatibility of hydrogels was evaluated by cytotoxicity and hemolytic experiments,and the application prospect of hydrogels in cell therapy was explored by cell encapsulation experiments.In vivo,The hydrogel was injected subcutaneously into SD rats,and the bulge model was established.The degradation performance of the hydrogel was evaluated by apparent analysis.The skin tissue of the corresponding part of the filling hydrogel was excised for pathological examination to evaluate the biocompatibility and in vivo degradation performance of the hydrogel.Results: According to the designed synthesis scheme,the structure of Chondroitin sulfate was modified to obtain aminosulfated Chondroitin sulfate CSADH and aldehyde sulfated Chondroitin sulfate CS-CHO.Through the Schiff base reaction,a new type of cross-linked CS hydrogel was prepared.The infrared results showed the modification of the hydrogel precursor and the binding mode of the hydrogel.The results of scanning electron microscopy showed the threedimensional network structure of hydrogels.The water absorption experiment results showed that the three proportional hydrogels had water binding ability primely.The rotational rheology reflects that hydrogels also had adhesion and elastic properties superiorly.Especially in the case of middle and low frequency,the corresponding moduli of the two properties of hydrogels were stable;in the case of high frequency,the elastic modulus and storage modulus increase sharply,and the hydrogels have the tendency of p Hase conversion and might break.However,the dynamic imine bond property of hydrogels can repair the damaged hydrogels in a short time.In vitro,the results of cytotoxicity test showed that the hydrogel extract had no significant inhibitory effect on the activity of HFF-1 cells.The hemolytic test results showed that the hydrogel had no hemolytic effect.Meanwhile,the results of hydrogel encapsulation experiments show that hydrogels have a good development prospect in cell therapy.indicating that the hydrogel had good degradation performance.Pathological results show that although it will cause certain inflammatory reactions within a certain period of time,such inflammatory reactions are very small compared with the wound repair,and the hydrogel itself has anti-inflammatory properties.As the hydrogel degrades,it can act as a palliative treatment during the inflammatory p Hase.Conclusions: In this study,a new crosslinked Chondroitin sulfate hydrogel was prepared successfully,which has excellent injection performance,stability,biocompatibility and degradability,and has broad development and application prospects in cell therapy,tissue engineering and medical beauty filling.