NanoScienceWorks

Catherine Murphy

Guy F Lipscomb Professor of Chemistry

Research Interests:

Metal and semiconductor nanomaterials; luminescent probes of DNA structure and dynamics; nanocomposite materials; inorganic coordination complexes for optical sensing.

We make inorganic nanomaterials for optical sensors. One overall goal is to incorporate our sensor materials into fiber optics with Prof. S. Michael Angel and his group to do remote detection of species such as water, protons, and ions in complex environments.

We have developed seed-mediated growth procedures to make metallic nanorods of controlled size and shape in aqueous solution. These nanorods, and nanowires, are brightly colored, and the wavelengths of light that they absorb and scatter depend on nanoparticle shape. We are developing improved methods to make these materials and are exploring biological sensing applications and other optical applications with them.

We characterize particle size by transmission electron microscopy in the USC Electron Microscopy Center.

Transmission electron micrograph of gold nanorods that are 20 nm wide and 80 nm long on average..

Darkfield microscopic image of white light elastically scattered by gold nanorods (bright spots) in a collagen gel (misty blues and browns). Field of view is approximately 1 mm.

We also think about DNA as a "nanomaterial" in terms of its local structure and dynamics. We have used our inorganic nanoparticles as optical probes of DNA structure. In addition, fluorescence resonance energy transfer experiments, in which organic donor and acceptor molecules are covalently attached to the ends of DNA, also provide information about DNA bending in solution, in the absence of particles. We are collaborating with R.S. Coleman (Ohio State University) and Prof. Mark Berg (here at USC) to explore the ultrafast dynamics of DNA within the base stack, by monitoring time-resolved Stokes shifts of a fluorescent base-pair analog, which ultimately will tell us about intrinsic sequence-dependent DNA flexibility. This is an example of the rich scientific, collaborative environment at USC that makes the scientific experience here so rewarding.

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Education

Catherine Murphy obtained her B.S. in 1986 at the University of Illinois-Urbana; her Ph.D. in 1990 from the University of Wisconsin-Madison.

Awards

She has been awarded with several awards, the National Science Foundation CAREER Award, 1995–1998; Cottrell Scholar Award, 1996–2001; Alfred P. Sloan Foundation Research Fellow, 1997–1999; Camille Dreyfus Teacher-Scholar Award, 1998–2000; Golden Key Faculty Award for the Integration of Research and Undergraduate Teaching, 1998; Michael J. Mungo Award for Excellence in Undergraduate Teaching, University of South Carolina, 2001; Outstanding Undergraduate Research Mentor Award, University of South Carolina, 2003; USC Russell Research Award for Science, Mathematics and Engineering, 2005.

Important Articles

Publications:

Berry, V.; Gole, A.; Kundu, S.; Murphy, C.J.; Saraf, R.F. "Deposition of CTAB Terminated Nanorods on Bacteria to Form Highly Conducting Hybrid Systems," J. Am. Chem. Soc. 2005, 127, 17600-17601.

Orendorff, C.J.; Baxter, S.C.; Goldsmith, E.C.; Murphy, C.J. "Light Scattering from Gold Nanorods: Tracking Material Deformation," Nanotechnology 2005, 16, 2601-2605

Murphy, C.J.; Orendorff, C.J. "Alignment of Gold Nanorods in Polymer Composites and on Polymer Surfaces," Adv. Mater. 2005, 17, 2173-2177.

Murphy, C.J.; Sau, T.K.; Gole, A.; Orendorff, C.J.; Gao, J.; Gou, L.; Hunyadi, S.Li, T. "Anisotropic Metal Nanoparticles: Synthesis, Assembly, and Optical Applications," J. Phys. Chem. B 2005, 109 13857-13870.

Gou, L.; Murphy, C.J. "Fine-Tuning the Shape of Gold Nanorods,"Chem. Mater. 2005, 17, 3668-3672.

Andreatta, D.; Perez Lustres, J.L.; Kovalenko, S.A.; Ernsting, N.K.; Murphy, C.J.; Coleman, R.S.; Berg, M.A. "Power-Law Solvation Dynamics in DNA from Measurements over Six Decades in Time," J. Am. Chem. Soc. 2005, 127, 7270-7271.

Orendorff, C.J.; Gole, A.; Sau, T.K.; Murphy, C.J. "Surface Enhanced Raman Spectroscopy of Self-Assembled Monolayers: Sandwich Architecture and Nanoparticle Shape Dependence," Anal. Chem. 2005, 77, 3261-3266

Murphy, C.J.; Sau, T.K.; Gole, A.; Orendorff, C.J. "Surfactant-Directed Synthesis and Optical Properties of One-Dimensional Plasmonic Nanostructures," MRS Bulletin. 2005, 30, 349-355.

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