LAUSR

A novel liposomal hydrogel with enzyme triggered release of drug as drug carrier was presented for usage of infected wound. The liposomal hydrogel was prepared by an acombined method of thin-film evaporation and supercritical carbon dioxide technique (TE-scCO2) with freeze-drying. In the liposomal hydrogel, curcumin as a model drug was embedded in the bilayer of the liposomes, and the liposomes were encapsulated in the gelatin-chitosan hydrogel. Phospholipase A2 (PLA2) riched in wound exudate was served tactfully as a trigger to hydrolyze lecithin in liposome and destroy the liposomes to release drug. Hydrolysis of phospholipids in liposomes was monitored by fluorescence assay of the released curcumin, and relationship between the hydrolysis of lecithin and the release of drug was discussed. The microstructure changes of the liposome after treated by PLA2 were probed by using florescence probeembedded in the liposomes for the first time. Besides, relationship between the microstructure of liposome and hydrolysis of liposome was revealed. This liposomal hydrogel can not only inhibit the degradation of drug in conveying process and enhance the efficiency of drug release to the infected skin, but also the release of drugs can be on demand by PLA2 biological activity changed with wound exudate in infected tissue.