With support from the Chemical Measurement and Imaging Program in the Division of Chemistry, Professor Duan at University of California, Los Angeles, designs and develops a new generation of nanoscale optical voltage sensors (NOVS) based on core/shell nanoparticles with a core of plasmonic nanostructure and a shell of nonlinear-optical (NLO) material. The design of plasmonic/NLO core/shell nanoparticles creates a new signaling pathway to sensitively and rapidly convert the local voltage signal into a detectable optical signal. This project focuses on designing, synthesizing and investigating the electro-optical sensor of described core/shell nanoparticles, and exploring the feasibility of using the optimized sensors for monitoring cell membrane potential. The design of optical reporters of voltage signal is of considerable interest for diverse applications, particularly for recording cell membrane potentials that are essential for high throughput, high space and time resolution. Such applications can be used to examine neural circuits, an integral component of brain activities. In line with the NSF "Understand the Brain" initiative, the successful development of the described NOVS may greatly expand our capability in detecting, imaging and monitoring dynamic neural activities to provide insight on brain function. Professor Duan's research program is closely integrated with education and outreach activities to broadly disseminate the research results. His program provides students with educational and training opportunities. He also works with the California NanoSystems Institute to help training high school teachers to bring new nanotechnology concepts to their high school science classes.
Professor Duan is developing nanoscale optical voltage sensors (NOVS) consisting of a core/shell nanoparticles with a core of plasmonic nanostructure and a shell of nonlinear-optical (NLO) material. He uses an external electrical field to actively modulate the dielectric environment and thus its plasmonic resonance spectrum, creating a new signaling pathway to sensitively and rapidly transfer the local voltage signal into a detectable optical signal. This project includes five research and educational activities: (1) to use finite element simulation to guide the design of a series of plasmonic/NLO core/shell nanostructures with desired plasmonic properties and electro-optical modulation; (2) to develop robust chemistries to synthesize the plasmonic core with controlled composition, morphology, dimension and the plasmonic resonance properties; (3) to use single particle spectroscopy to investigate the electro-optical modulation and the voltage sensitivity of the designed core/shell nanoparticles; (4) to explore the feasibility of using the optimized NOVS for monitoring cell membrane potential; and (5) to integrate fluorescence materials with the plasmonic/NLO nanoparticles to convert scattering-based plasmonic signal to fluorescence signal.