Polyion Complex Micelles Composed of All-Trans Retinoic Acid and Poly (Ethylene Glycol)-Grafted-Chitosan YOUNG-IL JEONG, 1 SANG-HYO KIM, 2 TAE-YOUNG JUNG, 2 IN-YOUNG KIM, 2 SAM-SUK KANG, 2 YONG-HAO JIN, 1 HYANG-HWA RYU, 1 HEUNG-SUK SUN, 1 SHUGUANG JIN, 1 KYUNG-KEUN KIM, 3 KYU-YOUN AHN, 3 SHIN JUNG 1,2 1 Brain Tumor Research Laboratory, The Research Institute of Medical Science, Chonnam National University Medical School, Gwangju 501-746, Republic of Korea 2 Department of Neurosurgery, Chonnam National University Hwasun Hospital, 160, Ilsim-ri, Hwasun-eup, Hwasun-gun, Jeollanam-do, 519-809, Republic of Korea 3 Research Institute of Medical Sciences, Chonnam National University, Gwangju, Republic of Korea Received 14 May 2005; revised 6 December 2005; accepted 24 December 2005 Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/jps.20586 ABSTRACT: 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  200 nm. The loading efficiency of micelle was higher than 80% (w/w) for all formulations. 1 H nuclear magnetic resonance (NMR) spectra confirmed the formation of polymeric micelles. The CP graft copolymer and ATRA have distinguishing peaks in their 1 H NMR spectra. The specific peaks of ATRA disappeared in D 2 O or DMSO while it appeared at mixtures of D 2 O/ 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. ß 2006 Wiley-Liss, Inc. and the American Pharmacists Association J Pharm Sci 95:2348–2360, 2006 Keywords: PEG-grafted chitosan; all-trans retinoic acid; ion complex; polymeric micelle; brain tumor cell INTRODUCTION Chitosan is a natural polymer derived from chitin by deacetylation. Since chitosan is regarded as biocompatible, biodegradable, and nontoxic, it is an interesting biomaterial because of its ability to be used as a drug carrying material and its ease of modification. 1 Furthermore, chitosan has been reported to enhance drug delivery across the nasal or mucosal layer without any damage being incurred by the drug. 2,3 Despite its superiority as a biomaterial, chitosan has the disadvantage of not being fully soluble in water and only being soluble in acidic solution. The fact that chitosan is only soluble in acidic aqueous solution limits its use as a bioactive agent in such applications as gene, peptide, and drug delivery. However, water-soluble chitosan which can be easily dis- solved in neutral aqueous solution have recently been reported by several authors. 4,5 The advan- tage of these water-soluble chitosan is their ease of modification and utility as carriers for gene, peptide drugs, or other types of drugs. 6 Retinoic acid (RA) and its analog, the retinoids, regulate cell behavior during development and play key roles in cell fate determination, cell division, and cell differentiation. 7 RA has been observed to promote neuronal survival, drive 2348 JOURNAL OF PHARMACEUTICAL SCIENCES, VOL. 95, NO. 11, NOVEMBER 2006 Correspondence to: Shin Jung (Telephone: þ82-61-379- 7666; Fax: þ82-61-379-7673; E-mail: sjung@chonnam.ac.kr) Journal of Pharmaceutical Sciences, Vol. 95, 2348–2360 (2006) ß 2006 Wiley-Liss, Inc. and the American Pharmacists Association