N-isopropylacrylamide (NIPAM) was copolymerized with -acryloyl-L-Lysine (ACRLLY) using N

N-methylenebisacrylamide (BA) as crosslinker through surfactant-free emulsion polymerization to prepare temperature-sensitive microgels containing free amino acid in side chains.Transmission electron microscopy (TEM)

dynamic light scattering (DLS) technique and turbidimetric method were employed to characterize the morphology and the volume-phase transition temperatures (VPTT) of microgels prepared.TEM results shows that the microgels have regular spherical morphology and the size of microgels decreases with the increase of the content of ACRLLY.DLS and turbidimetric analysis indicate that the size of microgels has monodisperse narrow distribution and the size of the microgels decreases with the increase of temperature indicating that the microgels have apparent VPTT.the VPTT of the P(ACRLLY-co-NIPAM) microgels can be successfully tuned by changing the content of the hydrophilic comonomer ACRLLY

and the VPTT of the microgels increases almost linearly with the feed ratio of ACRLLY.The Doxorubicin (DOX) delivery of microgels indicates that the microgels release 56% DOX uptaked at 20℃ and 73% at 37℃ in 12 h.However the microgels release 73% DOX uptaked at 37℃ in 13 h under the pH 7.4 and almost completely release under the pH 4.5.The above-mentioned results shows that the microgels prepared have excellent drug delivery property in different temperature and pH conditions.