CHEMO AND PHOTOTACTIC NANO/MICROBOTS
Ayusman Sen
Department of Chemistry,
The Pennsylvania State University
University Park, PA
Tuesday March 1, 2011
11:00 am – 12:00 pm
Fung Auditorium
Abstract:
One of the most interesting scientific challenges is the design of autonomous synthetic nano/micromotors which can be used for drug delivery, self-assembly of superstructures, roving sensors, and other emerging applications. We have demonstrated that one can build nanomotors “from scratch” that mimic biological motors by using catalytic reactions to create forces based on chemical gradients. In biological systems, microorganisms not only move autonomously, but also respond to their environment via the phenomenon of taxis: the movement towards or away from a chemical (chemotaxis) or light (phototaxis). We have recently observed the first examples of non-biological chemo and phototaxis. For example, when placed in a gradient of fuel, the motors spontaneously migrate up the concentration gradient. This behavior provides a novel way to direct particle movement towards specific targets. We have also explored self-diffusiophoresis as an alternative mechanism to power synthetic micro/nanomotors,. We have shown that particles that release ions under UV illumination exhibit the phenomenon of phototaxis. Further, the gradients produced by adjacent particles interact and the particles began to swarm into schools. Thus, the particles are reminiscent of quorum sensing organisms that swarm in response to a minimum threshold concentration of a signaling chemical.
Biosketch:
Ayusman Sen was born in Calcutta, India and holds a Ph. D. from the University of Chicago where he was first introduced to catalysis. Following a year of postdoctoral work at the California Institute of Technology, he joined the Chemistry Department of the Pennsylvania State University where is currently a Distinguished Professor. He is a Fellow of the American Association for the Advancement of Science. His research interests encompass catalysis, organometallic and polymer chemistry, and nanotechnology. He is the author of approximately 290 scientific publications and holds 23 patents.