Polyion complex micelles composed of all-trans retinoic acid and poly (ethylene glycol)-grafted-chitosan.

The goal of this study is to develop novel types of polyion complex micelles for the drug delivery to brain tumor. Methoxy poly(ethylene glycol) (mPEG)-grafted chitosan (CP) was synthesized in order to make polymeric micelles encapsulating all-trans retinoic acid (ATRA) based on polyion complex formation. Polyion complex micelles were found to have spherical shapes with sizes of about 50 approximately 200 nm. The loading efficiency of micelle was higher than 80% (w/w) for all formulations. 1H nuclear magnetic resonance (NMR) spectra confirmed the formation of polymeric micelles. The CP graft copolymer and ATRA have distinguishing peaks in their 1H NMR spectra. The specific peaks of ATRA disappeared in D2O or DMSO while it appeared at mixtures of D2O/DMSO, indicating that ATRA and chitosan formed ion complex inner-core. In the cell cytotoxicity study using U87MG cells in vitro, polyion complex micelles showed similar cytotoxicity to that of free ATRA. A migration test was performed to investigate the inhibition of tumor cell invasion in vitro. The results suggested that the polyion complex micelles was more effective at inhibiting tumor cell migration than free ATRA. Copyright 2006 Wiley-Liss, Inc. and the American Pharmacists Association