Báo Cáo pH AND TEMPERATURE SENSITIVE BIODEGRADABLE BLOCK COPOLYMER HYDROGELS AND MICELLES FOR BIOMEDICAL APP

1. INTRODUCTION
The stimuli-sensitive hydrogels and micelles have attracted considerable attention as intelligent materials in the biochemical and biomedical field, since they can environmental changes and induce structural changes by themselves. Among the stimuli-sensitive materials, the block copolymer hydrogels composed of poly(ethylene glycol)(PEG) as hydrophilic part and biodegradable polyester as hydrophobic part, such as poly(L-lactic acid)(PLLA), poly(D,L-lactic acid)(PDLLA), poly(D,L-lactic acid-co-glycolic acid)(PLGA) were studied as controlled-release drug carriers, because the hydrogels need not to be removed by surgical treatment owing to their biodegradability after injecting to body. Kim and coworkers reported the PLGA-PEG-PLGA block copolymer hydrogel has been used as an injectable drug delivery system, owing to its remaining in the gel form for a long time in the body.
However, these hydrogels have several unresolved drawbacks, which make them difficult to use in injectable drug delivery systems. When temperature reversible hydrogels are injected into the body by using a syringe, they tend to change into the gel in the wormed needle by the body temperature. These appearances make it difficult to inject them into the body.
In this presentation, we would like to review our recent works on the novel pH & temperature sensitive block copolymer hydrogels and micelles to overcome these
above unresolved problems.