My interests broadly span experimental studies of protein dynamics and photophysics in vitro and in vivo, and development of optical tools to explore biological function. Over the past several years we developed innovative new methodology integrating spectroscopy with flow cytometry. Although we continue to deepen our understanding of molecular dynamics with femtosecond and longer-timescale spectroscopy in vitro, we have broken new ground by developing microfluidics-based single-cell spectroscopy techniques to characterize photophysics in vivo on 105–member libraries of fluorescent proteins. We are performing selections to isolate clones with new properties and discover structure-dynamics relationships that would not be apparent from conventional biophysical studies focusing on a small number of variants. We have also developed a microfluidic method to initiate and monitor the dynamics of ratiometric biosensors in single cells within a population, and the capability to sort libraries based on the magnitude or kinetics of the sensor response. These and other novel technologies developed in my lab are integral to our directed evolution strategies for creating new biophotonic functionalities. The payoffs we envision range from discovery of new molecular dynamics underlying the unique photophysical properties of chromoproteins to biological applications benefitting from the improved visualization and control of cellular events.
PhD Physics (Montana State University, Bozeman);
MS Physics (Montana State University);
BS Physics (Kazan State University, Kazan, Russia).
Ph.D. Chemistry, The University of Texas at Austin
B.S. Chemistry, Louisiana Tech University
FRET-based biosensors engineered from naturally occurring fluorescent proteins have been widely used to image the distributions of small molecules and ions in living cells. However, the development of these imaging tools is often based on selections from libraries of random mutants, and little is known about the molecular aspects of the sensors that affect their FRET efficiencies. I am using spectroscopic techniques to characterize the structural changes of a variety of FRET-based Zn2+ sensors upon Zn2+ binding, with the goal of guiding the rational design of mutant libraries. By combining the in vitro characterization of these sensors with rapid, microfluidic selection techniques in cells, I aim to generate new sensors for Zn2+ that have improved cellular performance.
Ph.D. (Physics and Chemistry), Joint degree between Washington State University and Katholieke Universiteit Leuven, Belgium
M.S. (Physics), National Sun Yat-Sen University, Taiwan
B.S. (Physics), Fu Jen Catholic University, Taiwan
New generations of red fluorescent proteins (RFPs) with improved photophysical and photochemical properties will greatly benefit bioimaging applications in biological and biomedical research, and engineering new RFPs with desirable optical properties is of great interest to me. I am currently developing new spectroscopic methodology to further advance the capability of the flow cytometry in directed evolution of RFPs. Another focus of my work is to understand sequence-function relationships of RFPs to guide the design of new RFPs.
2nd Year Physics Graduate StudentBachelor of Science in Physics, Michigan State University
I have a variety of interests in quantum optics, chemical physics and biophysics which have led me into the Quantum Biometrology research project. Entangled two photon absorption (ETPA) in certain molecules has an orders-of-magnitude increased cross section. This opens doorways for using reduced laser power in biological imaging. The ETPA cross section is sensitive to the time separation of the photon pair, but needs thorough study. I'm working on generating optimal entangled photons for ETPA in molecules and finding well-suited molecules for ETPA as a biological imaging technique.
5th year Physical Chemistry PhD Candidate
Bachelor of Science, Agnes Scott College
I am interested in using physical chemistry techniques to understand biological systems. I am currently developing a new technique for RNA imaging in live cells. This involves utilizing spectroscopy and microfluidic techniques to understand and improve the photophysical properties of fluorescent sensors for biological imaging. My project uses time-correlated single photon counting (TCSPC) lifetime measurements, fluorescence intensity measurements, and microfluidic device fabrication and screening.
3rd year Physical Chemistry Ph.D. Candidate
Integrated Bachelor and Master of Sciences, IISER Mohali, India
Light matter interactions in biological media provide great insight into molecular events that give us information about largely unknown or unaccounted phenomena. Using methods in spectroscopy and employing ideas of chemical physics, one can gain significant insight into the dynamics of such systems. Red Fluorescent Proteins (RFPs) have been an area of active research and their photo-physics has been of phenomenal interest. The dynamics of fluorescent and dark state conversion (DSC) make them great candidates for standard and super-resolution imaging. Currently, I am investigating the photophysical properties in several clones of Red Fluorescent Proteins generated through directed evolution by using microfluidic screening assays, with the ultimate objective of development of RFP clones aimed at superior imaging properties, so as to be incorporated on single molecule, ensemble and living in flow systems.
I see fluorescent protein photophysics as a fascinating intersection of physical chemistry, biochemistry, and biophysical research. I am curious about the "blinking" intermittency observed in many fluorescent proteins upon illumination, and the insight it can provide into the nature of dark states and the process of photobleaching.
Professional Research Associates
BS (Mechanical Engineering), Ohio State University
MBA, Pepperdine University
Ph.D. (Biochemistry), University of Colorado – Boulder
As a Senior Research Associate at JILA, my work is focused on developing high throughput, analytical instruments to evaluate cyanobacteria and algae for their biofuel/biochemical production potential. These evaluations are performed at the single cell level and are capable of measuring physical properties such as cell size (based on forward scattered light), chlorophyll content, photosynthetic efficiencies (real-time quantum yield measurements) and lipid production (using lipid-specific fluorescence stains). Previous research concentrated on custom-built, microfluidic cytometers that were used to assess the effect of culture conditions upon lipid production in diatoms (Phaeodactylum tricornutum). Previous collaborations with major research labs investigated synergistic properties of mixed algal/cyanobacterial populations. Current research focuses on selection/sorting schemes to assist research in library screens, signal transduction pathway discovery and strain improvement. Work on these projects is rewarding because of the challenging mix of engineering, physical, biological and biochemical sciences.
Ph.D. Cornell University, Biochemistry, Molecular and Cell Biology
B.S. Molecular, Cellular and Developmental Biology, University of Colorado
I have a relatively broad background in the life sciences, from examining photoreceptor proteins in plants, HIV and SIV protein structure/function and DNA replication proteins in yeast to exploring how temperature influences disease susceptibility and microbial community dynamics in Caribbean corals. I have also acted as a scientific consultant in regulatory toxicology issues, as a general bioscience editor and as a laboratory manager. I hope to apply this uniquely diverse skillset towards furthering the efforts of the Jimenez lab.