Self-aggregates of cholesterol-modified carboxymethyl konjac glucomannan conjugate: Preparation, characterization, and preliminary assessment as a carrier of etoposide

Various cholesterol (CH) bearing carboxymethyl konjac glucomannan (CKGM) amphiphilic conjugates (denoted CHCKGM) were synthesized using CKGM as hydrophilic segments and CH as hydrophobic parts. Structural characteristics of these CHCKGM conjugates were investigated using FTIR, (1)H NMR and thermogravimetric analysis (TGA). The properties of these self-aggregates were analysed by dynamic laser light-scattering (DLS), zeta potential, transmission electron microscopy (TEM) and the fluorescence probe technologies. The critical aggregation concentration (cac) of CHCKGM conjugates (2.59 x 10(-3) to 5.89 x 10(-3) mg/mL) was comparatively low, suggesting that the cholesterol fragment was very effective for forming aggregates. Etoposide was physically entrapped into the CHCKGM nanoparticles by sonication method. The in vitro release behavior of etoposide from CHCKGM nanoparticles revealed a sustained release property. Furthermore, these self-aggregated nanoparticles showed pH- and ionic strength-dependent properties which caused a considerable change in their radius. (C) 2011 Elsevier Ltd. All rights reserved.