Seminar: "Stimulated Raman: Building Better Biosensors,
Making Medical Discoveries, and Understanding Fundamental Biophysics" by
Dr. Ryan M. Gelfand
Thursday, May 28, 2015 11:00 AM to 12:00 PM
CREOL Room 102
CREOL Room 102
Celebrating the International Year of Light 2015
Dr. Ryan M. Gelfand
Abstract:
For over a century optical spectroscopy has been an integral
tool for determining the structure, composition, and function of biological
molecules. When small molecules bind together to form macromolecules the
intermolecular resonances are found between 0.3 to 10 THz: the terahertz gap.
Current sources and detectors at these frequencies are impractical for large
scale, fast, sensitive and inexpensive molecular studies. By using the beat
frequency between two laser sources one can perform high resolution
spectroscopy across a very large frequency range (including the THz regime)
while still using readily available visible and NIR optical components. This
frequency difference creates a strong electrostriction force that excites
Raman active vibrational modes. Once excited, the increased motion of the
particle influences the optical signal which can be recorded by using a lock-in
amplifier. To increase the efficiency and sensitivity of this technique it is
coupled to a single nanoparticle optical aperture trap. Within this trap one
can study the structure of proteins without tethers and in their native
environment; comparing how different therapies impact the behavior of these
important biological molecules. Development of this technique will enable
researchers to gain insight into both protein-protein and protein-small
molecule interactions leading to advances in disease treatments, potentially
for neurodegenerative disorders. Furthermore, because the setups are versatile
they can be used to study other nanoparticle systems as well (for example:
semiconductors, carbon materials, florescent molecules, etc).
These stimulated Raman methods are not only simply limited
to optical traps. By using them in conjunction with an AFM, this spectroscopic
functionality can be added to force microscopy measurements. By looking at the
effect of an excited particle near a plasmonic hotspot fabricated onto the
facet of one of the lasers, sensitive and selective optical detection can be
achieved by looking at the change in differential resistance of the laser. This
would eliminate the need for bulky, cooled photodetectors and enable compact,
portable, and potentially disposable biosensor devices. Two photon stimulated
Raman techniques will allow us to more easily access the THz region, add extra spectroscopic
functionality to already existing methods, and provide researchers with a new
tool to study fundamental sciences.
Biography:
Dr. Ryan M. Gelfand is an NSF funded postdoctoral researcher
in electrical engineering at the University of Victoria with Prof. Reuven
Gordon and Northwestern University. He received his Ph.D. in electrical
engineering (solid state and photonics division) from Northwestern with Prof.
Hooman Mohseni, and his B.S. in physics from Carnegie Mellon. Between those
degrees he worked as a pharmaceutical chemist for Abbot Labs in Chicago. Ryan
was awarded an NSF Fellowship in Biology in 2013 for a program entitled:
Intersections of Biology and Mathematical and Physical Sciences and
Engineering. His research interests and experiences have always been at the
intersection between the physical sciences and biology.
For additional information:
Dr. Aristide Dogariu
407-823-6839
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