46. [J. Polym. Res.] A pH-triggered charge reversal and self-fluorescent micelle as a smart nanocarrier for doxorubicin controlled release
writer：Shan Xia, Yang Gao, Zhe Yu, Lijie Duan, Guang Hui Gao
keywords：Charge reversal , Self-fluorescent , pH-sensitive , Micelles
source：期刊
specific source：J Polym Res
Issue time：2017年
A novel pH-sensitive charge reversal and selffluorescent polymeric micelle is designed and synthesized successfully. The smart micelle is prepared based on MPEGpolyurethane multi-block copolymer, which is synthesized by polycondensation, with 1, 4-bis (hydroxyethyl) piperazine (HEP) and hydroxyl-sulfamethazine (Hydroxyl-SM) as pHsensitive molecules and fluorescein isothiocyanate (FITC) as fluorescent segment. The resulting MPEG-polyurethane multi-block copolymer is examined by 1H–NMR, UV-vis spectra, fluorescence spectra and an acid-base titration. Moreover, the diameter, morphology and cytotoxicity of obtained polymer micelle are measured by dynamic light scattering (DLS), transmission electron microscopy (TEM) and MTT assay. The results indicate that the micelle has a small diameter of less than 200 nm and can remain unchanged within two weeks. Zeta-potential measurement shows that the negative charge of micelle can switch into positive charge as the pH value decreasing from 9.0 to 3.0. Subsequently, the fluorescence intensity decreases significantly with the reducing of pH values. The MTT assay shows the low cytotoxicity and good biocompatibility of the MPEG-polyurethane polymeric micelles. Finally, doxorubicin (DOX) is loaded into micelles to detect in vitro release behavior. The drug loaded micelles show a faster release behavior at pH 5.0 than that at pH 7.4. Therefore, the pH-sensitive charge reversal and selffluorescent micelle can be a potential smart carrier for delivery and controlled release of protein drug.