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Research Overview
Our research focuses on measuring and manipulating colloidal and macromolecular interactions, dynamics, and structures on macroscopic substrates. This has broad relevance to traditional complex fluid applications (coatings, ceramics, foods) and emerging nanotechnologies related to fabrication of devices (sensors, diagnostics, microfluidics) and materials (photonic, biomimetic). The objective is to develop experimental and analytical tools to rationally manipulate material properties and process characteristics with explicit consideration of thermodynamic and kinetic factors inherent to the colloidal domain. In our group, colloidal interactions are measured with exquisite sensitivity by monitoring equilibrium and non-equilibrium structures using optical microscopy and scattering methods. To interpret and predict the control parameters in interfacial colloidal systems, we employ analytical and simulation techniques to rigorously model many-body, low Reynolds number hydrodynamics and particle interactions on the order of kT.
Within this broad framework, we have several immediate areas of interest. We are developing novel combinations of total internal reflection, video, and confocal microscopy techniques to allow direct, real space measurement of three dimensional colloidal trajectories in interfacial ensembles. These methods are being used to investigate colloidal photonic crystal assembly on templated substrates, the use of colloids as novel probes of biomolecular microarrays, measurements of metal nanoparticle-surface interactions, and "imaging" of potential energy landscapes on heterogeneous surfaces. Our initial work has focused on a stepwise escalation of experimental and analytical complexity from single-particle/wall problems to multi-particle/wall problems, which provides a foundation for understanding increasingly complex interfacial colloidal and macromolecular systems.
Current areas of focus
Stokesian dynamic simulations of interfacial and confined colloidal systems.
Multi-body & multi-dimensional interfacial colloidal forces and hydrodynamics.
Patterned potential and free energy landscapes interrogated using diffusing
colloidal probes.
Colloidal self assembly on chemically and physically patterned substrates.
Colloidal directed assembly using external applied fields.
Phase behavior tuned via temperature & specific ion dependent polymeric
forces.
Equilibrium & non-equilibrium colloidal structure characterization
and manipulation.
Protein-protein & protein-synthetic macromolecule interactions using nanoparticle
probes.
Personnel
Recent Ph.D. Graduates
Samartha Anekal - Stokesian
Dynamics of Interfacial and Confined Colloidal Systems
Hung-Jen Wu - Mapping Energy
Landscapes with Diffusing Colloidal Probes
Doctoral Students
Pradipkumar Bahukudumbi - Controlling
Interfacial Electrical Properties via Colloidal Microfluidic Circuits
Richard Beckham - Multidimensional
Interfacial Colloidal Crystallization on Patterns
Shannon Eichmann - Diffusing
Colloidal Probes of Mutant Protein-Protein Potentials of Mean Force
Neil Everett - Biomolecular
Interactions on Combinatorial Arrays using Quantum Dots
Gregory Fernandes -
Colloidal Assembly via Solvent Quality Dependent van der Waals and Depletion
Potentials
Mingqing Lu - Connecting
Interfacial Colloidal Microstructure and Potentials via Density Functional Theory
Undergraduate Research Students
Blake Bennett - Crystallization
from Attractive Sub-Monolayer Colloidal Fluids
Tracie Book - Equilibrium Partitioning
and Dynamics of Colloids on Patterned Surfaces
Visiting Researcher
Daniel Beltran - Inverse Analyses of Sub-Monolayer
Colloidal Fluids
Equipment
Zeiss inverted confocal scanning laser microscope - 3D dynamic imaging
Zeiss inverted fluorescence microscope with CCD camera - fluorescence and
general imaging
Zeiss upright microscope with PMT & CCD camera - single particle and
ensemble TIRM
Brookhaven static/dynamics light scattering goniometer/autocorrelator - particle
shape, size, and interactions
Brookhaven ZetaPALS - particle sizing and electrophoresis
Paar Physica MCR 300 rheometer - rheological measurements
Funding
American Chemical Society Petroleum Research Fund
Defense Advanced Research Projects Agency
National Science Foundation
The Welch Foundation
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