Synthesis, characterization and biocompatibility of poly(2-ethyl-2-oxazoline)–poly(d,l-lactide)–poly(2-ethyl-2-oxazoline) hydrogels

A novel thermoreversible hydrogel based on poly(2-ethyl-2-oxazoline)-derived amphiphilic triblock copolymer, poly(2-ethyl-2-oxazoline)–poly(d,l-lactide)–poly(2-ethyl-2-oxazoline) (PEOz–PLA–PEOz), was developed. The synthesis of PEOz–PLA–PEOz was carried out by coupling monohydroxylated PEOz–PLA diblocks with adipoyl chloride as coupling agent and dimethylamino pyridine as catalyst. The tube inverting and rheological tests showed that triblock copolymers had sol–gel–sol transition behavior with increasing temperature, and the gelation was found to be thermoreversible. The critical gelation concentration, the sol–gel transition temperature at a given concentration depended on the EOz/LA ratio and the molecular weight of PEOz. Scanning electron microscopy observation revealed that the resultant bulky gel exhibited an interconnected porous three-dimensional (3D) microstructure after freeze-drying. In addition, the hydrogels showed good cytocompatibility in vitro. MTT assays revealed that the human skin fibroblast cells encapsulated within the hydrogels were viable and proliferated inside the 3D scaffold. This newly described thermoreversible hydrogel demonstrated attractive properties to serve as cell matrix for a variety of tissue engineering applications or pharmaceutical delivery vehicles.