Chemistry Project Abstract
BILE SALTS AND CHOLESTEROL NUCLEATION
Presenter:
Annie Ko, Illinois Mathematics and Science Academy, 1500 West Sullivan Road, Aurora, IL, 60506; annik7@imsa.edu
Mentor:
Dr. Steven Wrenn, Drexel University, College of Engineering, 3141 Chestnut Street, Philadelphia, PA, 19104; 215-895-6694; wrenn@drexel.edu
Abstract:
Gallstone disease – a widespread human disease that involves crystallization of cholesterol – is caused by accumulation of macroscopic cholesterol crystals that precipitate from biliary vesicles (50-100 nm in diameter). Vesicles, in which cholesterol resides, are thermodynamically unstable, and cholesterol eventually precipitates from the vesicle when equilibrium is obtained. However, humans are not at equilibrium, and the question of who develops gallstones depends heavily on the rate at which cholesterol leaves vesicles to yield crystals; several chemical species in bile are known to influence this rate. The objective of this research was to examine the process by which cholesterol crystals form in a model bile system. Synthetic vesicles exposed to bile salts NaTDC, NaTUDC, and NaTC were examined. Using dynamic light scattering and UV spectroscopy, the micro-structural transition from vesicles to micelles was observed. Four distinct zones characterized this transition, depending on the bile salt concentration, giving rise to varying levels of vesicle aggregation and micellization. No significant correlation was seen between the interaction of vesicles with these various bile salts.