Chirality is fundamental to many physical, chemical, and biological systems, impacting processes as diverse as pharmaceutical-cell interactions to the evolution of species. Measuring molecular chirality is especially important to synthesize chiral compounds, study enzymatic interactions, and understand dynamic protein folding and DNA hybridization. Current methods to measure molecular chirality rely on ensemble techniques such as circular dichroism spectroscopy. However, these techniques require large analyte concentrations and relatively long integration times. Measuring molecular chirality at the few-to-single molecule level and in real time remains an outstanding challenge. In this talk, I will discuss how light can be sculpted with engineered nanostructures to enhance chiral light-matter interactions. With these nanostructures, we have developed metamaterial biosensors and optical force nanoscopes to detect and visualize molecular chirality with high sensitivity and resolution. Specifically, we have designed a multilayer twisted metamaterial sensor which can detect down to zeptomoles of proteins within milliseconds. Additionally, we have developed a metamaterial-enhanced atomic force microscope to image chiral optical forces with nanometer spatial resolution and piconewton force sensitivity. We use this technique to measure the chirality of DNA molecules, approaching the single molecule level. These studies provide a foundation for new sensing and imaging techniques at the single molecular to cellular level in-situ and in real time.
Yang Zhao is an assistant professor at the University of Illinois, Urbana-Champaign, Department of Electrical and Computer Engineering. She is affiliated with the Micro and Nanotechnology Laboratory and has a courtesy appointment with the Department of Bioengineering. Her lab develops nano-optical and photonic tools including metamaterials and optical force nanoscopy, and using these new tools for imaging and sensing applications. She received her PhD degree from the University of Texas at Austin, where she studied with Professor Andrea Alù in the Department of Electrical and Computer Engineering. Her PhD research undertook both computational theory and experimental realization of metasurfaces as flat optical elements to manipulate light-matter interactions at the nano-scale. She received her postdoctoral training with Professor Jennifer A. Dionne in the Department of Materials Science and Engineering at Stanford University. At Stanford, her research focused on developing a new generation of plasmonic optical tweezers for directly manipulating molecules and optical force spectroscopy tool for mapping three-dimensional chiral force-fields. She is a coauthor of 25 papers in peer-reviewed journals, and a recipient of the Michael H. Granof Outstanding Dissertation Award (from the University of Texas) and Carl E. Anderson Outstanding Doctoral Dissertation Award (from the American Physical Society).