Alenka Luzar, Ph.D.
Ph.D., University of Ljubljana, Slovenia
Sabbatical leaves: University of Puerto Rico (1984), State University of New York at Stony Brook (1985), University of California at Berkeley (1990-1992), Princeton University (2013)
Fellow, American Physical Society, since 2008
Fellow, American Association of Advancement of Science, since 2010
VCU College of Humanities and Sciences Distinguished Scholar Award, 2012
International steering committee member of the ICSC (International Conference on Solution Chemistry sponsored by IUPAC), 2013 – 2021
Elected Vice-Chair, Gordon Research Conference of Water and Aqueous Solutions, 2016
Elected Chair, Gordon Research Conference of Water and Aqueous Solutions, 2018
Physical and theoretical chemistry, biophysics, materials by design, condensed phase chemical dynamics. Multiscale modeling and Statistical mechanics. Neutron scattering experiments in liquid condensed matter.
- Applications to structure and dynamics of polyatomic liquids, phase transitions and interfacial chemistry: water and aqueous solutions, theoretical chemical kinetics and reactivity, liquids at interfaces (including colloidal, surfactant and biological interfaces), confined and metastable liquids, supercritical fluids,
- Applications to molecular biophysics and biophysical chemistry: intermolecular forces, conformational dynamics and folding kinetics, biomacromolecular solvation, hydration in drug design, self-assemblies, protein-protein interactions,
- Applications to materials science: wetting/dewetting, adhesion, manipulation of surface properties and surface force studies, soft materials.
Our research is focused on understanding the dynamics and structure of molecular liquids, in particular interfacial and confined water, hydrogen-bonded mixtures, and inter-surface forces in biological and materials systems. Understanding the basic mechanisms involved in hydration processes in biology and nanotechnology is taking us a step closer to creating new biomimetic materials, harvesting energy from nature and storing energy. To do this we combine theoretical approaches and computations at multiple length and time scales. We emphasize realistic atomistic descriptions of complex molecular systems, as well as development of simple analytical models that are able to capture the essential physical properties of a system in question. We do both equilibrium and non-equilibrium statistical mechanics. Our computational efforts involve the development of algorithms. An important feature of our work is the close contact we pursue between theory and experiment. Current applications are briefly outlined below, together with recent representative publications:
Electrowetting in nanoscale systems
Electrowetting, which renders surfaces more hydrophilic, has useful applications in ink-jet printing, microfluidics, and might enable voltage-gating of flow through nanochannels. Electrowetting over nanoscale dimensions presents significant departures from the conventional picture known from macroscopic systems. Orientational anisotropy of water molecules, associated with interfacial hydrogen bonding, introduces a notable dependence of wetting propensity and polarization dynamics on the direction and polarity of the external electric field. Our modeling studies explore this dependence and the resulting trend toward the interface alignment with the field as a novel mechanism to order nanomaterials. Control of surface hydrophilicity by the applied field provides opportunities for the design of miniature optical lenses comprised of nanosized droplets, where the lens power can be maintained under precise electric control. Our research of electrowetting by nanodroplets on dielectric (EWOD) concerns optimization of the dynamic response of these devices and their suitability in electro-optical applications
Dynamic Response in Nanoelectrowetting on a Dielectric, J. R. Choudhuri, D. Vanzo, P. A. Madden, M. Salanne, D. Bratko and A. Luzar, ACS Nano, 10, 000 (2016), DOI: 10.1021/acsnano.6b03753
Nanoconfined water under electric field at constant chemical potential undergoes electrostriction, D. Vanzo, D. Bratko and A. Luzar, Journal of Chemical Physics 140, 074710 (2014)
Dynamics at a Janus Interface, M. von Domaros, D. Bratko, B. Kirchner and A. Luzar, Journal of Physical Chemistry C 117, 4561 (2013)
Nanoscale wetting under electric field by molecular simulations, C. D. Daub, D. Bratko and A. Luzar, Topics in Current Chemistry 103, 155 (2012)
Electric control of wetting properties by salty nanodrops: molecular dynamics simulations, C. D. Daub and D. Bratko and A. Luzar, Journal of Physical Chemistry C 115, 22393 (2011)
Microscopic dynamics of hydrated nanoparticle orientation in an electric field, C. D. Daub, D. Bratko, T. Ali and A. Luzar, Physical Review Letters 103, 207801 (2009)
Water-mediated ordering of nanoparticles in an electric field, D. Bratko, C. D. Daub and A. Luzar, Faraday Discussions 141, 55 (2009)
Field-exposed water in a nanopore: liquid or vapour? D. Bratko, C. D. Daub and A. Luzar, Physical Chemistry Chemical Physics 10, 6807 (2008)
Effect of Field Direction on Electro-wetting in a Nanopore, D. Bratko, C. D. Daub, K. Leung and A. Luzar, Journal of the American Chemical Society 129, 2504 (2007)
Electrowetting at the Nanoscale, C. D. Daub, D. Bratko, K. Leung and A. Luzar, Journal of Physical Chemistry C (Letter) 111, 505 (2007)
Smart and Bio-inspired Surfaces
Nanoscale patterning of surface topography offers a powerful way to tune surface wetting without altering the surface chemistry. Through molecular modeling, we are designing surfaces with extreme resistance to wetting (superhydrophobic) akin to lotus leaf in nature, which show a promise for passive drag reduction. We are also interested in the design of novel switchable surfaces whose properties are actively under control (smart surfaces). By molecular modeling we are exploring actuation rates of surface tension, contact angle, and nanodroplets shape under external stimuli. These are critical dynamic properties for designing efficient switchable nanofluidic and optical devices.
Wetting transparency of graphene in water, J. Driskill, D. Vanzo, D. Bratko and A. Luzar, Journal of Chemical Physics 140, 18C517 (2014)
Metastable sessile nanodroplets on nanopatterned surfaces, J. Ritchie, J. Seyed Yazdi, D. Bratko and A. Luzar, Journal of Physical Chemistry C 116, 8634 (2012)
The influence of molecular-scale roughness on the surface spreading of an aqueous nanodrop, C. D. Daub, J. Wang, S. Kudesia, D. Bratko and A. Luzar, Faraday Discussions 146 (2010)
Energy and Nano-Materials
Emerging nanoparticle technologies require new techniques to control surface properties of a material. Surface thermodynamics and interactions between nanoparticle surfaces are often determined by solvation in electrolyte solutions. Our goal is to develop molecular level understanding of energetics, kinetics and hydration of nanoparticle dispersions in water and ionic solutions, and to introduce novel separation techniques. Through molecular modeling studies, we are learning how to design new media for surface energy storage, tune nanomaterial’s wetting properties either permanently (by functionalization) or transiently (by applied fields), and how to sequester ions or drive water against concentration gradient. Electrowetting by, and spontaneous expulsion of aqueous solution from, hydrophobic pores provides a mechanism for switchable wetting/dewetting processes for applications in surface energy storage and nanofluidic devices manipulated by external electric field. The development of novel open ensemble algorithms is an essential component of these activities.
Salt and water uptake in nanoconfinement under applied electric field: an open ensemble Monte Carlo study, F. Moucka, D. Bratko and A. Luzar, Journal of Physical Chemistry C 119, 20416 (2015)
Electrolyte pore/solution partitioning by Expanded Grand Canonical Ensemble Monte Carlo simulation, Moucka, D. Bratko and A. Luzar, Journal of Chemical Physics 142, 124705 (2015)
Dynamic control of nanopore wetting in water and saline solutions under an electric field, D. Vanzo, D. Bratko and A. Luzar, Journal of Physical Chemistry B 119, 8890 (2015)
Wetting free-energy dependence on the density of ionic functionalities, D. Vanzo, D. Bratko and A. Luzar, Journal of Physical Chemistry C 116,15467 (2012)
Wettability of pristine and alkyl-functionalized graphane, D. Vanzo, D. Bratko and A. Luzar, Journal of Chemical Physics 137, 034707 (2012)
Computational Probes of Water in Biological Systems
To identify the role of water in biology is a hot, but still controversial topic. The cell water determines how macromolecules interacts with one another, how they move. Yet we still do know little about what cell water is like. Here are a few outstanding questions our lab is contributing to answer: What are the conditions for wet and dry hydrophobic protein cavities? What is the structure of water around various amino acids, small building blocks of proteins? What it’s dynamics like? How does the hydrophobic force, most universal of forces controlling biological assembly, work? How is it affected by dissolved gas? How is it affected by the solute curvature?
Universal repulsive contribution to the solvent-induced interaction between sizable, curved hydrophobes, B. S. Jabes, D. Bratko and A. Luzar, J. Phys. Chem. Lett. 7, 3158 (2016).
Computational probe of cavitation events in protein systems, J. H. Wang, S. Kudesia, D. Bratko and A. Luzar, Physical Chemistry Chemical Physics 13, 19902 (2011)
Length-scale dependence of hydration free energy: effect of solute charge, J. H. Wang, D. Bratko and A. Luzar, Journal of Statistical Physics (Special Issue on Water and Associated Liquids) 145, 253 (2011)
Probing surface tension additivity on heterogenous surfaces by a molecular approach, J. H. Wang, D. Bratko and A. Luzar, Proceedings of the National Academy of Sciences of the United States of America 108, 6374 (2011)
Structure of aqueous solutions of monosodium glutamate, C. D. Daub, K. Leung and A. Luzar, Journal of Physical Chemistry B 113, 7687 (2009)
Attractive surface force in the presence of dissolved gas: a molecular approach, D. Bratko and A. Luzar, Langmuir 24, 1247 (2008)
Neutron Scattering in Condense Phase Systems
We initiated and continue to maintain collaboration with the world’s leading experimental groups in the United Kingdom and France on neutron diffraction with isotope contract variation and dynamic neutron scattering to investigate the molecular rearrangements that occur when water responds to organic molecules with or without significant polarity, and its hydrogen bond dynamics.
Investigations on the structure of dimethyl sulfoxide and acetone in aqueous solutions, S. E. McLain and A. K. Soper and A. Luzar, Journal of Chemical Physics 127, 174515 (2007)
Dynamics of Hydrogen Bonds: How to probe their role in the unusual properties of liquid water, J. Teixeira and S. Longeville and A. Luzar, Journal of Physics: Condensed Matter 18, S2353 (2006)
Orientational Correlations in Liquid Acetone and DMSO: A Comparative Study, S. E. McLain and A. K. Soper, Journal of Chemical Physics 124, 074502 (2006)