Friday, September 14 at 4:00pm
A. Paul Schaap Science Center, 1000
35 East 12th Street, Holland, MI 49423-3605
Dr. Scott Thorgaard; Grand Valley State University - Electrochemical Collisions: Interrogating Nanoparticles and Bacteria One at a Time
Abstract: Electroanalytical methods based on electrochemical collisions have enabled the time-resolved monitoring of single nano- and micro-scale objects. In these experiments, individual nanoparticles or biologicals are detected by their ability to enhance or inhibit electron transfer reactions
occurring at an ultramicroelectrode (UME) when they strike the electrode surface. Electrochemical collisions have shown promise for investigations of nanomaterials at pM to fM concentrations, and have recently been applied to numerous systems including the characterization of metal or semiconductor
nanoparticles and the monitoring of individual viruses and bacteria.
In my research group at Grand Valley State University, we are applying electrochemical collisions in multiple projects, which will be highlighted in my talk. One project has focused on the detection of single metal nanoparticles using a variant of electrochemical collisions based on catalytic amplification.
This project aims to probe differences in catalytic activity for different nanoparticle materials on a single particle basis. Our experiments to date have monitored electrochemistry occurring at single Pt, Rh, Ir, and Au nanoparticles. A second project has focused on the detection of electrically insulating particles by their ability to inhibit (block) diffusive mass transport at a UME. We have been successful in applying blocking collisions for the detection of several different bacteria species at fM concentrations.
Incorporation of simultaneous fluorescence imaging to the electrochemical experiments allowed elucidation of single bacteria adsorption (or repulsion) events at UMEs. Species-dependent differences found in the collision experiments suggest applications of this method in devices for selective bacteria sensing.
Biography: Dr. Thorgaard is a faculty member in analytical chemistry at GVSU. He got his Ph.D. from the University of Minnesota in 2010 and then did a two-year postdoc at the University of Texas at Austin. Following that he spent two years as a visiting professor at Winona State University before finally landing at GVSU in 2014. His background is primarily in electroanalytical chemistry, with an emphasis on developing fundamental physical chemical understanding of electrochemical phenomena.