Improved Synthesis Of Cysteine Modified Hyaluronic Acid For In Situ Hydrogel Formation/Preparation And Characterization Of Polyurethane Foam Dressings

Hyaluronic acid (HA) is a natural non-sulfated anionic linear polysaccharide, widely presented in the human body. As a biocompatible, non-immunogenic and anti-inflammatory natural product, HA has been used as cosmetics, medical devices and therapeutics.However, hyaluronic acid has a relatively short half-life in the body, readily degradated by the hyaluronidase in vivo in a range of a few minutes to two or three days, limited its broad use in the field of therapeutics. Chemical modification and cross-linking of HA has been used to obtain longer residence time in vivo while maintaining its biocompatibility and viscoelastic properties.In this study, lyophilization was used and discovered to promote the reaction between the primary hydroxyl groups of HA and the glycidyl ether of allyl glycidyl ether to form an ether bond linkage and generate allyl functionalized HAs while mainly retaining its free carboxyl groups, thus maintaining the active interaction between hyaluronic acid and CD44 receptor. A new thiol compound for cysteine functionalization of HA was synthesized by an improved new method and new strategy for protection of functional groups, reacted with the allyl HAs using thiol-ene click chemistry to generate new hyaluronic acid-cysteine conjugates,further reacted with a four-armed polyethylene glycol oxyester to form hydrogel, indicating that the new hyaluronic acid-cysteine conjugates were chemically reactive.The formation of hyaluronic acid hydrogels and formed hydrogels were characterized by rheological studies and cytotoxicity of the hydrogels was studied by cell culture.Rheological studies showed that the hyaluronic acid hydrogels were injectable and in-situ formed, chemically crosslinked, highly viscoelastic and controllable for gel formation time.Cytotoxicity studies indicated that these hydrogels were not cytotoxic and had no effect on cell proliferation and did not inhibit cell survival.In summary, the injectable and in situ formed hyaluronic acid hydrogels reported here could have broad application prospects in treatment of arthritis, drug delivery, tissue filling,tissue repair and tissue engineering.In the healing process of skin wounds, dressings as temporary substitutes for damaged skin are essential medical products that promote wound healing, Traditional dressings,such as gauze,although can be used for therapeutic purposes, the adhesion and poor moisturizing properties will give patients with uncomfortable and secondary injuries.A foam dressing is a wound dressing consisting of a unique polyurethane foam, This dressing can be made into any desired shape, to a large extent to meet the requirements of different body parts on the dressing shape, Polyurethane foam dressing can be closely covered in the wound skin, for providing the appropriate humidity and temperature to wound surface. What’s more,the polyurethane foam dressing also has good flexibility,moisture absorption and biocompatibility.In this paper, the hydrophilic polyurethane foam dressing was prepared and prepared by crosslinking using toluene diisocyanate (TDI) and polyethylene glycol (PEG) by analyzing the shortcomings of traditional dressings. At the same time, the subject also studied the ratio of raw materials and the amount of catalyst used on the impact of material properties. In order to meet the requirements of dressing performance, the effects of morphology observation, liquid absorption, moisturizing property and coagulation rate on foam dressing were studied. The results show that the final preparation of polyurethane foam dressing can be used as medical dressing materials for further research and development.