IIN Frontiers in Nanotechnology Seminar Series – Jennifer Cha

Professor Jennifer Cha

Department of Chemical and Biological Engineering
University of Colorado Boulder

Abstract

With increasing demands for alternative sources of fuel, extensive research has focused on discovering methods to generate renewable energy from earth-abundant resources. In recent years, a wide range of
inorganic nanostructures with high surface areas and tunable band gaps have been synthesized and used as photocatalysts. To increase their activity, “Z-scheme” photocatalytic systems have been implemented in
which multiple types of photoactive materials simultaneously oxidize water and reduce molecules upon photoillumination. In this talk, Dr. Cha will discuss her recent efforts to utilize DNA as a structure-directing agent to organize well-defined photoactive donor and acceptor nanocrystals into optimal configurations. In the first part, she will demonstrate that using DNA as a structure directing agent to assemble TiO2 and Pt-decorated CdS nanocrystals caused a significant improvement in water splitting as opposed to utilizing a single typle of particle or simply mixing the particles in solution. In addition, DNA also allowed positioning of a single or series of electron mediators site-specifically between the two catalysts to further increase H2 production. In a similar vein, she will also discuss some of her recent efforts in applying Z-schemes for reducing CO2 to usable fuels. In the latter part of the talk, Cha will showcase her very recent efforts to
apply a bioinspired approach to tailor protein-nanoparticle interfaces for studying photoassisted redox activity. In order to drive enzymatic reduction of dissolved gases, electron sources such as photocatalysts and
electrochemistry have been studied. However, in order to optimize electron flow, there is a significant need to understand how the interface between the organic enzyme and inorganic semiconductor influences protein
binding and dynamics. Many redox enzymes function through assembly of protein subunits utilizing complex and multivalent interactions, with binding strengths ranging from long-range and weak to short-range and near-covalent. Mimicking such exquisite binding motifs is likely to be key for replacing protein subunits with photoactive semiconductors. This talk will showcase recent insight into the design of interfaces between semiconductor surfaces and proteins to control binding and conformational dynamics of enzymes to promote photodriven redox catalytic activities.

Biography

Jennifer Cha obtained her PhD in Materials Chemistry from UC Santa Barbara in 2001 with Profs. Galen Stucky, Dan Morse, and Tim Deming. She then completed postdoctoral research with Prof. Paul Alivisatos at UC Berkeley from 2002-2004. Following this, she worked as a research staff member at the IBM Almaden Research Center, where she started a program focused on using bionanotechnology for nanoelectronics. In 2008, she began her academic career in the Department of Nanoengineering at UC San Diego, receiving tenure in 2012. In July 2012, she joined the Department of Chemical and Biological Engineering at the University of Colorado, Boulder where she is currently a David Clough Endowed Professor. Her group’s research focuses on the design and use of bio-nanotechnology to synthesize and create well-defined
organic-inorganic systems from nanoscale building blocks. Specific applications include engineering protein therapeutics, using DNA for engineering photocatalytic architectures and developing bioinspired
interfaces for catalysis. Over the last few years, she has received a DARPA Young Faculty Award, an NSF CAREER award, a DOE Early Career Award, and a Sloan Award.