Controllable release of ibuprofen from thermo-sensitive poly(N-isopropylacrylamide) hydrogel

Thermo-sensitive poly(N-isopropylacrylamide)(PNIPAAm) hydrogel was prepared by free-radical in water.With hydrophobic ibuprofen(IBU) as mode drug,the thermo-sensitive property of PNIPAAm and interaction with IBU were studied.The IBU release behavior was investigated in phosphate buffer solution(PBS,pH 7.4) at different temperatures(25 ℃ and 37 ℃).It was found that a lower critical solution temperature(LCST) of PNIPAAm around 33 ℃ and interacted with IBU by intermolecular hydrogen bond.The IBU released slower at 37 ℃(above LCST) than at 25 ℃ (bellow LCST) in PBS.Therefore,the release of IBU from the thermo-sensitive PNIPAAm hydrogel could be controlled by changing the temperature around LCST.