Preparation and characterization of self-assembled nanoparticles of the novel carboxymethyl pachyman-deoxycholic acid conjugates

Various novel carboxymethyl pachyman-deoxycholic acid conjugates (CMPD) were synthesized using carboxymethylated pachyman (CMP) as a hydrophilic segment and Deoxycholic Acid (DOCA) as a hydrophobic segment. The degree of DOCA substitution (DS) in CMPD conjugates, which was determined by elemental analysis, can reach to 30.0, 49.2, or 54.9 DOCA groups per hundred sugar residues of CMP. Structural characteristics of these CMPD conjugates were investigated by using H-1 NMR, dynamic light scattering, zeta potential, transmission electron microscopy (TEM) and fluorescence spectroscopy. The CMPD conjugates provided apparently smaller monodispersed self-aggregates in water. with mean diameters decreasing with increasing of DOCA DS in the range of 98-158 nm. Zeta potentials of the CMPD self-aggregated nanoparticles indicated that the nanoparticles were covered with negatively charged CMP shells. TEM images demonstrated that the nanoparticles were spherical in shape. The critical aggregation concentration (cac) of the CMPD nanoparticles (1.55 x 10(-2)-5.89 x 10(-3) mg/mL) was comparatively low which implies that the CMPD self-assembled nanoparticles form at low concentration in aqueous solution. (C) 2008 Elsevier Ltd. All rights reserved.