Joan E. Curry

Associate Professor

Ph.D., Chemistry, 1992,
University of California, Davis
B.S., Chemistry, 1982,
United States Naval Academy

Office: Family and Consumer Resources, Rm. 310
Tucson, AZ 85721

Phone: (520) 626-5081
Fax: (520) 621-1647

Email: curry@ag.arizona.edu

RESEARCH INTERESTS

Chemistry at Interfaces Important in Lubrication and Adhesion, Biomacromolecular Interactions, Organized Molecular Assemblies, and Environmental Systems

My field of research is interfacial chemistry, which is a focus within physical chemistry. Within interfacial chemistry, I focus on chemistry of molecules at the interfaces where solids and liquids come together. The term solid here includes mineral and bacterial surfaces found in soils and sediments, metal and oxide machine surfaces and cell surfaces found in the human body. Molecules can be water and ions that bathe soil surfaces, organics that lubricate machine parts and large biomacromolecules, such as proteins and lipopolysaccharides, attached to cells that mediate cell adhesion. My specific interests are (1) determining the effect of confinement on liquids in general and lubricants in particular and (2) characterizing the adhesive properties of cell surface biomacromolecules.

Research

Computer Simulation of Lubricants and Confined Fluids

It is important to understand the molecular basis of lubrication and flow in thin films in order to improve the simulation of naturally occurring porous media and to design more efficient and environmentally friendly lubricants. When a liquid is confined between two closely spaced surfaces whose separation is comparable to molecular dimensions as in a soil micropore or in an ultrathin lubricant film the liquid no longer has the same properties and behavior it would have in the bulk. The molecular nature of the liquid becomes important and anomalous properties such as solidlike behavior and stick-slip sliding emerge. Theories reliable for large pores and thick lubricant films break down making it very difficult to predict how liquids will behave when confined. Hence, confined liquids are poorly understood. We study lubricant films from the molecular point of view by simulating the individual molecules of the lubricant film on a computer using molecular dynamics and Monte Carlo computer programs developed in our laboratory.

Characterization of the adhesive properties of cell surface biomacromolecules

The primary goal of this work is to understand how biomacromolecules that cover cell surfaces influence the interaction and adhesion of cells with other cells and with solid surfaces. Cells can be either bacteria or human cells. It is important to understand bacterial adhesion because it is the first step in biofilm formation, which has numerous undesirable consequences ranging from heat exchanger fouling to medical implant infections. Currently, very little is known about how bacterial surface biomacromolecules mediate adhesion and therefore it is still not possible to control or manipulate the process. Human cell adhesion is also mediated by biomacromolecules, in particular proteins that bind to one another through specific lock and key mechanisms. The structure of many cell adhesion proteins is well known but their function is still poorly understood. In collaboration with Ronald Heimark (Surgery) we are working to understand how heavy metals such as cadmium affect the binding of cell adhesion proteins called cadherins. This work will help us understand better how heavy metals may lead to birth defects and in adults could accelerate cardiovascular disease. This work is experimental and involves direct force measurements between biomembrane covered mica surfaces with the Surface Forces Apparatus (SFA). With the SFA it is possible to measure the magnitude and distance dependence of molecular forces acting between two flat surfaces with angstrom and nanonewton resolution. The instrument is shown below.