Novel pH Switchable Micelle/Polymerosome Vehicles For Controlled Release Of Anticancer Drugs.

A novel pH sensitive monomer, 2- (methacryloyloxy)ethyl-3-chloro-4-hydroxybenzoate (MCH), was synthesized and co-polymerized with mPEG475MA by RAFT polymerization yielding an amphiphilic block copolymer. At physiological pH the copolymer spontaneously assembled in micelles of about 30 mm in size, while at pH 6.5 rearranged in 80 nm vesicles. The micelles were loaded with the anticancer drug tamoxifen at 10 wt%. At pH 6.5, the drug was released 1.6 times more rapidly than at pH 7.4.. Accordingly, the in vitro anticancer activity against MCF-7 cells was higher at pH 6.8 compared to pH 7.4. Pharmacokinetic studies in mice showed that the colloidal system improves the permanence of the anticancer drug in the bloodstream.