Biodegradable microspheres with poly( N-isopropylacrylamide) Enriched surface: Thermo-responsibility, biodegradation and drug release.

Microspheres with thermo-responsible surface were fabricated by PCL- b-PEO- b-PNIPAM triblock copolymers. Thermo-responsible morphological changes of PCL- b-PEO- b-PNIPAM microspheres immersed in aqueous solution at temperatures above the LCST ( e.g. 37 °C) were observed from porous surface structure to compact surface layer. Enzymatic degradation and in vitro drug release results showed that the thermo-responsible surface layer greatly influenced the degradation of microspheres as well as the drug release behavior from microspheres. With the copolymerization of PNIPAM block into PCL- b-PEO copolymers, the drug release could be well regulated by changing temperatures and microspheres composition, which revealed the great potentials of microspheres with thermo-responsible surface for controlled drug release. [ABSTRACT FROM AUTHOR]