Effect of Counterions on Micelle Formation for Drug Protection Delivery

Abstract

By Robert Burns, Biological Sciences; Dominic Duponty, Chemistry and Philosophy

Advisor: Clifford Larrabee

Presentation ID: PM_D18

Abstract: Aqueous micelle solutions currently have applications ranging from home cleaning products to drug delivery to environmental remediation. Micelles have been well researched however, one area where the research is less abundant is the fundamental effect of hydrophobic counterions on micelle formation. These counterions have the capacity to form a protective layer around the micelle, which further decreases drug interaction with the environment. Here we show the results of fluorescence experiments and molecular dynamics simulations on the effects of a series of different counterions on undecylenic acid-based micelles. The fluorescence results show two decreasing trends with increasing hydrophobicity: first, decreasing critical micelle concentrations (CMC), second, decreasing micelle aggregation numbers. The molecular dynamics simulations indicate that the micelles are spherical in shape and have an average diameter of 3.0 nm (without the counterions). The least hydrophobic counterions, tetramethylammonium and tetraethylammonium, do not form a distinct layer at the surface of the micelle. In contrast, the more hydrophobic tetrapropylammonium and tetrabutylammonium counterions form two distinct layers at the surface of the micelle. These layers surrounding the micelle, have the capability to further protect encapsulated drugs from interacting with the environment. The applications of this newfound fundamental principle include enhanced vitamin uptake and even reducing the negative side effects of chemotherapy.