Autoagregados de lecitina e sais de bile na presença de carboximetilquitosana

Abstract

The modulation of self-associated systems by polymers plays a fundamental role in the development of colloidal formulations, enabling control over their rheological and structural properties. This work investigated the influence of carboxymethyl chitosan (CMQ) on systems formed by lecithin and the bile salts, sodium cholate (NaC), sodium deoxycholate (NaDC) or sodium taurodeoxycholate (NaTDC), in aqueous medium. CMQ was synthesized by three methodologies and characterized by Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). The CMQ-M1 sample was selected for presenting the highest yield (52.75%), more intense bands associated with carboxymethyl groups, and higher crystallinity (55.60%). Binary bile salt/lecithin systems were prepared at 1:1 and 1:2 ratios, followed by the addition of CMQ-M1 at concentrations of 0.5, 1.0, and 2.0% (w/w). The influence of the polymer was evaluated by dynamic light scattering (DLS), zeta potential, and rheological assays. The results showed that CMQ interacts in a manner dependent on the chemical nature of the bile salt and the ratio between the components. The results demonstrated that the behavior of these systems is strongly dependent on the structural differences among the bile salts. In systems containing NaC, CMQ increased the magnitude of the zeta potential and altered aggregate size, indicating greater colloidal stability. In systems containing NaDC, it reduced the zeta potential, favoring aggregation and disruption of the viscoelastic network. In systems containing NaTDC, it resulted in high zeta potential values, structural reorganizations, and increased viscosity, especially at the 1:1 ratio, where 2% CMQ led to phase separation. Overall, the results demonstrate that CMQ is an efficient polymer for modulating the structural, rheological, and stability properties of lecithin- and bile salt-based colloidal systems. These findings indicate the potential of these systems for pharmaceutical applications, such as formulations and controlled drug delivery systems.