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Brian Todd

Assistant Professor of Physics

E-mail: batodd@purdue.edu
Office: PHYS 68  Telephone: (765) 494-3004  

Education

B.ChE. Chemical Engineering, Georgia Institute of Technology, 1997
Ph.D., Biomedical Engineering, Case Western Reserve University, 2003

Research Interests

Single-molecule biophysics
Intermolecular forces and biological recognition
DNA gymnastics and gene regulation

Professional Experience

Assistant Professor, Purdue University, 2008-Present
Postdoctoral Fellow, National Institutes of Health, 2004-2008

Positions Open

Students interested in single-molecule instrumentation, experimental biophysics, and wet-mesoscale-room-temperature physics are encouraged to contact me regarding open RA positions.

Current Projects

DNA Gymnastics

In the course of storing and accessing genetic information, biological cells contort, mangle, stuff, and wiggle DNA about. The physical forces involved in this have a dramatic influence on the biology of gene regulation (how a cell knows WHAT gene to turn on WHEN). To understand this process at a statistical mechanical level, we grab onto DNA, do some contorting of our own, and measure the forces involved. This is accomplished via single-molecule sensitive force-measuring devices, such as, optical tweezers.

Single-molecule measurements

Our approach to understanding the molecular mechanics of biology is to sink to the molecule's level. This is accomplished by means of a focused laser or a microscopic magnet that allows us to literally grab onto a single molecule and feel the forces that it feels during the course of a biochemical reaction. From this we are building a statistical mechanical understanding of the the regulation of gene expression.

Fluorescence correlation spectroscopy

More recently, we've gotten interested in the dynamics of moving genetic information around the cell nucleus. We are working our way up by first measuring the conformational dynamics of DNA using fluorescence correlation spectroscopy (FCS). This allows us to probe the time scale for fluctuations in DNAs shape from the movement of fluorescent probes in and out of a small sample volume.

Selected Publications

  1. B.A. Todd, N.Y. Sidorova, D.C. Rau, C. Stanley Hydration Forces, Wiley Encyclopedia of Chemical Biology, doi:10.1002/9780470048672.wecb230
  2. B.A. Todd, V.A. Parsegian, A. Shirahata, T.J. Thomas, D.C. Rau Attractive Forces between Cation Condensed DNA Double Helices, Biophysical Journal, 94: 4775-4782, doi:10.1529/biophysj.107.127332 (2008)
  3. B.A. Todd, D.C. Rau Interplay of Ion Binding and Attraction in DNA Condensed by Multivalent Cations, Nucleic Acids Research, 36: 501-510 (2008)
  4. B.A. Todd, S.J. Eppell Probing the Limits of the Derjaguin Approximation with Scanning Force Microscopy, Langmuir, 20: 12, 4892-4897 (2004)