Preparation and characterizations of a novel deoxycholic acid-O-carboxymethylated chitosan-folic acid conjugates and self-aggregates

O-carboxymethylated chitosan (OCMC) was firstly hydrophobically modified with various deoxycholic acid (DOCA) to obtain a novel kind of amphiphilic polymer, and then covalently bound with folic acid (FA) to develop a new potential cancer-targeted drug delivery system. Structural characterizations of the conjugates were investigated using FTIR, H-1 NMR and XRD. The physicochemical properties of self-aggregates in aqueous media were studied by H-1 NMR, zetasizer, zeta potential, fluorescence spectroscopy, and transmission electron microscopy (TEM). The mean diameter of self-aggregates in PBS solution (pH 7.4) decreased with the degree of substitution (DS) of DOCA increasing. Zeta potential of self-aggregates exhibited near -20 mV in PBS solution (pH 7.4), indicating these nanoparticles were covered with negatively charged OCMC shells. The critical aggregation concentrations (cac) of the conjugates were dependent on the DS of DOCA and were significantly lower than those of low molecular weight surfactants. TEM images demonstrated that the shape of self-aggregates was spherical. Crown Copyright (C) 2011 Published by Elsevier Ltd. All rights reserved.