Lorenz De Neve
Ghent University, Belgium
Title: Influence of molecular structure and temperature on the adsorption behavior of PEO-PPOPEO surfactants: A QCM-D study
Biography
Biography: Lorenz De Neve
Abstract
Poly(ethylene oxide)-poly(propylene oxide)-poly(ethylene oxide) block copolymer surfactants (poloxamers or pluronics) are used as stabilizer in various nanosuspensions, e.g. of rilpivirine, danazol, diclofenac, asulacrine and itraconazole. In order to have a stabilizing effect on hydrophobic particles, these PEO-PPO-PEO surfactants should adsorb to the particle surface. In this research, the adsorption behavior of pluronics with two different ethylene oxide contents (50% and 80%) and three different molecular weights of the propylene oxide part (i.e. 950, 1750 and 3250 g/mol) was studied at 20°C and 37°C onto gold sensors coated with 1-undecanethiol using a quartz crystal microbalance with dissipation (QCM-D). Pluronic solutions with 5 different concentrations were used, ranging from 0.02 mg/ml to 50 mg/ml. Our results indicate a significant (linear) effect of the pluronic concentration on the average adsorption during the adsorption steps. No clear effect could, however, be detected after rinsing of the sensors with ultrapure water. The molecular weight of the PPO part seemed to have a proportional effect on the adsorbed amounts after rinsing, but no clear effect during the adsorption steps. The ethylene oxide content seemed to have an effect during both the adsorption and rinsing steps. Also, our results indicated no significant difference in the average adsorbed amount during both the adsorption and rinsing steps at 20°C and 37°C. The obtained results were useful to gain more insight in the stability differences between nanosuspensions with different pluronic concentrations (and molecular structure).