Joan E Curry
Associate Professor, BIO5 Institute
Professor, Environmental Science-Ext
Primary Department
Department Affiliations
(520) 626-5081
Research Interest
Joan Curry, PhD, stands in the field of research related to interfacial chemistry, which is a focus within physical chemistry. Within interfacial chemistry, she focuses 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. Her 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. 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), Dr. Curry is working to understand how heavy metals such as cadmium affect the binding of cell adhesion proteins called cadherins. This work will help scientists 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.

Publications

Kim, S., Cho, K., & Curry, J. E. (2005). Measurements of the thickness compressibility of an N- octadecyltriethoxysilane monolayer self-assembled on mica. Langmuir, 21(18), 8290-8296.

PMID: 16114933;Abstract:

The surface forces apparatus technique and the Johnson-Kendall-Roberts theory were used to study the elastic properties of an n- octadecyltriethoxysilane self-assembled monolayer (OTE-SAM) on both untreated and plasma-treated mica. Our aim was to measure the thickness compressibilities of OTE monolayers on untreated and plasma-treated mica and to estimate their surface densities and phase-states from the film compressibility. The compressibility moduli of OTE are (0.96 ± 0.02) × 10 8 N/m 2 on untreated mica and (1.24 ± 0.06) × 108 N/m 2 on plasma-treated mica. This work suggests that the OTE phase-state is pseudocrystalline. In addition, the results from the compressibility measurements in water vapor suggest that the OTE-SAM on both untreated and plasma-treated mica is not homogeneous but rather contains both crystalline polymerized OTE domains and somewhat hydrophilic gaseous regions. © 2005 American Chemical Society.

Diestler, D. J., Schoen, M., Curry, J. E., & Cushman, J. H. (1994). Thermodynamics of a fluid confined to a slit pore with structured walls. The Journal of Chemical Physics, 100(12), 9140-9146.

Abstract:

In this article we extend our previous thermodynamic analysis of films confined to slit pores with smooth walls (i.e., plane-parallel solid surfaces without molecular structure) to the situation in which the walls themselves possess structure. Structured-wall models are frequently employed to interpret experiments performed with the surface forces apparatus (SFA), in which thin films (1-10 molecular diameters thick) are subjected to shear stress by moving the walls laterally over one another at constant temperature, chemical potential, and normal stress or load. The periodic structure of the walls is reflected in a periodic variation of the shear stress with the lateral alignment (i.e., shear strain) of the walls. We demonstrate by means of a solvable two-dimensional model that the molecular length scale imposed by the structure of the walls precludes the derivation of a simple mechanical expression for the grand potential analogous to that which holds in the smooth-wall case. This conclusion is borne out by the results of a grand-canonical Monte Carlo simulation of the three-dimensional prototypal model consisting of a Leonard-Jones (12,6) fluid confined between fcc (100) walls. Criteria for the thermodynamic stability of thin films confined by structured walls are derived and applied to the SFA. © 1994 American Institute of Physics.

Curry, J. E. (2001). The mica slit-pore as a tool to control the orientation and distortion of simple liquid monolayers. Molecular Physics, 99(9), 745-752.

Abstract:

Grand canonical ensemble Monte Carlo computer simulations have been used to study monolayer octamethylcyclotetrasiloxane (OMCTS) and cyclohexane films confined between mica-like surfaces to determine the effect of the mica surfaces on the orientation and distortion of the films at different surface alignments. The film molecules are packed as a highly ordered lattice. The orientation of the lattice is fixed relative to the mica surfaces and depends on the size of the film molecule. Registry shifts distort the film lattice by effectively stretching it along a particular direction that depends on the size of the film molecule. For a particular registry, OMCTS and cyclohexane monolayers are stretched in perpendicular directions. Coupling between the monolayers and the mica surfaces generates a nonzero shear stress when the surfaces are out of alignment, but the film does not become disordered or melt. It is possible that precisely controlled solid surfaces could be used to create packed arrays of film molecules with desired orientation and degree of distortion that may be useful in nanotechnological applications.

Curry, J. E., & Cushman, J. H. (1995). Mixtures in slit-micropores with pore-walls structured on both the atomic and nanoscale. Materials Research Society Symposium - Proceedings, 366, 141-152.

Abstract:

The grand canonical Monte Carlo method is used to study a binary mixture of Lennard-Jones atoms confined to various corrugated slit-micropores which are in thermodynamic equilibrium with their bulk phase counterpart. The micropore walls have the structure of the (100) face of an fcc lattice. In addition to this atomic scale structure, one wall possesses nanoscale structure in the form of rectilinear grooves (corrugation). The grooved surface divides the confined fluid film into two strip shaped regions. The confined film is studied in each region as a function of groove width, bulk phase composition, and the size of the wall atoms.

Curry, J., Farrell, J., Luo, J., Blowers, P., & Curry, J. E. (2002). Experimental and molecular mechanics and ab initio investigation of activated adsorption and desorption of trichloroethylene in mineral micropores. Environmental science & technology, 36(7).

This research investigated activated adsorption of a hydrophobic organic contaminant(HOC) in mineral micropores using experimental and molecular modeling techniques. Adsorption of trichloroethylene (TCE) on a silica gel adsorbent was measured using a frontal analysis chromatography technique at atmospheric and elevated fluid pressures. Increasing the fluid pressure yielded increased TCE uptake that was not released upon lowering the pressure back to atmospheric conditions. This showed that the increase in pressure was able to rapidly induce the formation of a desorption-resistant fraction that previous investigations have shown requires months to develop at atmospheric pressure. Grand Canonical Monte Carlo (GCMC) modeling was then used to elucidate the nature of water and TCE behavior within silica micropores. The GCMC modeling showed that molecular scale packing restrictions resulted in pore fluid densities that ranged from 0.28 to 0.78 of those in the bulk solution. The modeling also showed that TCE was able to displace water from hydrophilic mineral pores due to molecular scale packing restrictions. Exothermic isosteric heats for TCE adsorption up to -27 kJ/mol were observed and were greatest in pores of 7 and 8 A. This indicated that TCE adsorption was energetically most favorable in pores that were minimally large enough to accommodate a TCE molecule. The pressure-induced uptake appeared to result primarily from an increase in the packing density in the smallest pores. Ab initio calculations showed that small distortions of a TCE molecule from its low energy conformation require high activation energies. Results from this study indicate that activated adsorption requiring bond angle distortions in the adsorbate may be responsible forthe slow attainment of adsorptive equilibrium of HOCs on microporous solids. Likewise, activated desorption from molecular-sized adsorption sites may contribute to the slow release of HOCs from aquifer sediments.