Preparation of a drug carrier through α-cyclodextrin-induced micellization of poly(ε-caprolactone-block-4-vinylpyridine) for controlled delivery of doxorubicin

Abstract

A novel method has been used to prepare the self-assembled supramolecular micelles which aid in the delivery of anticancer drugs. α-Cyclodextrin (α-CD) induces a micellization process of poly(e-caprolactone-block-4-vinylpyridine) (PCL-b-P4VP) copolymers through selective inclusion of PCL segments into the cavity of α-CD, resulting in the formation of pseudopolyrotaxane-b-P4VP. Compound pseudopolyrotaxane-b-P4VP forms supramolecular micelles in aqueous medium through self-assembly, which has been characterized using various analytical techniques. The resultant complex micelles consist of pseudopolyrotaxane as the core and P4VP chains in the outer shell, and the micelles possess a well-defined spherical morphology. The self-assembly process can easily be tailor-made by varying the number of PCL and P4VP segments in the PCLx-b-P4VPy copolymer. The arrangement of pseudopolyrotaxane-b-P4VP in the form of “channel-type” crystallites (derived from the supramolecular columns) is confirmed from the wide-angle X-ray diffraction (WAXD) patterns as well as by the composition of the inclusion complexes (ICs) calculated via proton nuclear magnetic resonance (1H NMR) spectral data. The biocompatibility of the micelles was evaluated by a cell viability test and the results revealed excellent cytocompatibility. The prepared micelles were used as carriers for the model anticancer drug doxorubicin (DOX) and successful drug release was observed with a loading content of 14.4 % (w/w) and a loading efficiency of 28.9 %. In vitro drug delivery was evaluated in phosphate-buffered saline (PBS) solution. DOX release from the micelles was considerably faster at pH 5.0 in comparison to a physiological pH of 7.4. The development of supramolecular self-assembled micelles based on partial IC formation between α-CD and compatible block copolymers opens a new, facile and attractive approach for designing novel drug carriers for future pharmaceutical applications.