Dr. Ardemis A. Boghossian, California Institute of Technology
Seminar Abstract
Plants have evolved highly sophisticated mechanisms of self-repair to regenerate proteins that become photo-damaged over time. In the absence of this self-repair cycle, plants demonstrate less than 5% of their photosynthetic yield, diminishing plant growth and lifetime. Key to this self-repair process is the reversible self-assembly of protein complexes, which is characterized by the molecular recognition of parts, kinetic trapping of meta-stable thermodynamic states, and chemical signaling to switch between states. In this seminar, we explore both biomimetic and natural regenerative mechanisms in an effort to develop biological light-harvesting devices with prolonged lifetimes. We demonstrate the first synthetic photoelectrochemical cell capable of mimicking key aspects of the self-repair cycle. The dynamic photoelectrochemical complex consists of two recombinant proteins, phospholipids, and a single-walled carbon nanotube (SWCNT) that reversibly assemble into a particular configuration, forming an array of lipid bilayers housing light-converting proteins. Surfactant addition and removal are used to signal between the disassembly and re-assembly of the photoactive complex, and a kinetic model reveals that the thermodynamically meta-stable complex can transition reversibly between free components and the assembled state at surfactant removal rates above 10-5 sec-1. Application of a biomimetic regeneration cycle increases photoconversion efficiency by more than 300% over 168 hours and extends the solar cell lifetime indefinitely. We also demonstrate the first intact, chloroplast-based biofuel cell. Application of regenerative, reactive oxygen species (ROS) scavenging nanoceria (NC) particles is shown to enhance the natural regeneration cycle and fuel cell power output. Thus, the interface of nanotechnology with biological, light-harvesting components enables a new generation of dynamic, biological solar cells with enhanced natural and biomimetic self-repair mechanisms.
Biography
Ardemis A. Boghossian is currently a postdoctoral researcher in the Frances H. Arnold lab at the California Institute of Technology. She received her B.S. in Chemical Engineering from the University of Michigan in 2007. In 2012, she received her Ph.D. in Chemical Engineering from the Massachusetts Institute of Technology under the supervision of Michael S Strano. As a NDSEG fellow, Ardemis has contributed to the experimental and theoretical development of nanotube-based optoelectronic devices for both light-harvesting and sensing applications. Her current postdoctoral research focuses on using protein engineering and directed evolution to address the solar energy challenge.