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Biological Physics

Research is carried out in both experimental and theoretical biological physics. Some current areas of interest are:

The adaptive optics and biophotonics group, directed by Professor Nolte, studies a broad spectrum of problems that range from BioCDs (Biological Compact Disks) that rely on diffraction of lasers from spinning discs supporting antibodies, to real-time video flythroughs of rat bone-cancer tumors using holographic imaging, and microfabrication of microfluidic systems using two-photon polymerization. The BioCD uses high-speed spinning-disc interferometry (SDI) to measure average changes in protein heights with sensitivities down to a picometer. These silicon discs are protein microarrays that have the ability to screen for hundreds of types of molecules across hundreds of samples. Holographic optical coherence imaging (HOCI) has high sensitivity to motion inside of tissues and cells. Using digital holography, we are studying the effects of anti-cancer drugs on the cytoskeleton. Laser machining using two-photon polymerization is a direct-write process that fabricates complex microfluidic systems. These projects use laser interferometry, nonlinear optics, coherent optics, and Fourier optics to study aspects of biological systems from the nanoscale molecular level to the macroscale tissue level.

Fe-dynamics in heme proteins. A new x-ray synchrotron technique is being exploited to measure the vibrational spectrum of iron atoms in the heme group of myoglobin and other proteins. The unique nature of this experiment allows one to isolate the contribution of the heme active site from the rest of the protein. In conjunction with the experimental work, new theoretical and computational approaches are being developed to study dynamics of macromolecules including normal modes of iron centers in proteins (Durbin, Prohofsky).

Ultrafast dynamics and photosynthesis. Using ultrafast laser techniques combined with site-directed mutagenesis, the structure-function relationship is studied in photosynthetic pigment-protein complexes. These studies can aid in the design of artificial photosynthetic systems and may result in efficient and environmentally safe sources of of energy (Savikhin).

Computational neuroscience with a focus on modeling neural networks and, more in general, on understanding how the nervous system works (Giordano).

Computational electronic structure of metalloproteins. The laws of quantum mechanics are applied, in conjunction with high performance supercomputers, to understand the electronic structure, reactivity and function of metal sites in proteins. In particular, density functional theory (DFT) is used to probe intricate electron-electron interactions and model spectroscopic data of antiferromagnetic centers in non-heme diiron-oxo proteins. In addition, genetic algorithms (GAs) are developed and used to perform computer simulations of experimental data (J. H. Rodríguez).

Membrane dynamics in living cells. Using single molecule imaging techniques (single particle and single fluorophore tracking) the motion and interactions of individual membrane molecules (proteins and lipids) are directly observed at video rates up to 100,000 frames/sec. From this, we hope to better understand how the machinery in the membrane is organized to carry out critical tasks, with an eye towards its applicability in medical sciences and in the development of active soft materials (Ritchie).