Preparation of pH/Light dual-responsive biocompatible polymer micelles: Application to curcumin delivery

Polymer micelles play an important role in the research of drug delivery system because of their nano-size, unique "core-shell" structure and surface modifiability. A pH/photosensitive drug carrier, PEG-PDMAEMA-PNBAE, was synthesized by atom transfer radical polymerization (ATRP) using hydrophilic poly (N, N dimethylaminoethyl methacrylate) (PDMAEMA) as the pH-responsive chain segment and hydrophobic poly (o-nitrobenzyl acrylate) (PNBAE) as the light-responsive chain segment. The molecular and structural characteristics of the polymer were spectroscopically characterized with Fourier transform infrared spectrometer (FT-IR), Nuclear magnetic resonance hydrogen spectrum (1H NMR) and Gel permeation chromatography column (GPC). The morphology and size of micelles were observed by Scanning electron microscope (SEM) and Transmission electron microscope (TEM). The stability of micelles was detected by Laser particle size analyzer (DLS). The Critical micelle concentration (CMC) of the polymer was analyzed by Fluorescence spectrophotometer (Flu), and the photosensitivity of the micelles was determined by Ultraviolet–visible spectrophotometer (UV). The results showed that the synthesized polymers could self-assemble into homogeneous and stable spherical micelles and their particle size was about 100 nm with effective light sensitivity. Curcumin (Cur) was used as a model drug to investigate the adsorption and release abilities of the micelles. The adsorption performance test of the polymeric micelles showed an encapsulation rate of 77.82% and a drug loading capacity of 13.46%. In vitro drug release results showed cumulative drug release rates of 31.79% and 46.55% at pH 5.5 and pH 5.5+UV, indicating the dual pH and light responsiveness of the synthesized carrier. The in vitro hemolysis and cytotoxicity test demonstrated that the carrier has good biosafety.