Photo-cross-linked mPEG-poly(γ-cinnamyl-l-glutamate) micelles as stable drug carriers†
A functionalized L-glutamate N-carboxyanhydride monomer containing a cinnamyl moiety, γ-cinnamyl-L-glutamate N-carboxyanhydride (CLG-NCA), was prepared. Ring-opening polymerization (ROP) of CLG-NCA initiated by n-hexylamine and amino-terminated poly(ethylene glycol) (mPEG-NH2) was successfully performed with controlled polymer molecular weight and molecular weight distribution. The structures of the obtained monomer and polymers were confirmed by 1H NMR, 13C NMR and FTIR. The block copolymer mPEG-b-PCLG could self-assemble into micelles in aqueous solution which consist of a hydrophobic PCLG core and a hydrophilic mPEG shell. Under UV-irradiation at 254 nm, the photo-cross-linking process of the cinnamyl-carrying block copolymer micelles was tracked by UV-Vis spectra, 1H NMR, dynamic light scattering (DLS) and transmission electron microscopy (TEM). In vitro MTT assay demonstrated that the micelles were biocompatible to L929 cells. Paclitaxel was loaded into the micelles as a model drug. The in vitro paclitaxel release behaviors indicated that cross-linking of the micelle cores results in a slow drug release in comparison with the non-cross-linked micelles. These results indicated that the photo cross-linked mPEG-b-PCLG micelles can be used as drug carriers for intelligent drug delivery.