I obtained my Physics Bachelor degree in 1995 from the University of Bucharest and my Physics Ph.D. degree under the supervisioon of Prof. Rienk van Grondelle and Prof. Herbert van Amerongen at the VU University Amsterdam, with a thesis on ultrafast spectroscopy of the primary events in photosynthesis. My thesis work provided, in correlation with the (incomplete at the time) protein crystal structures, a detailed map of the energy flow in the light-harvesting complex II (LHCII), the major light-harversting antenna system in plants. I also found evidence of a new singlet state in a bacterial carotenoid, which I "baptized" S* and showed that it converts surprisingly fast to the triplet state via a singlet-fission mechanism. The S* state has since been found in other carotenoids and similar photophysics has been observed in photovoltaic materials.
Between 2001 and 2003 I was a postdoctoral fellow at Leiden University in the single-molecule biophysics group of Prof. Thomas Schmidt. There I built an instrument capable of acquiring simultaneously atomic-force and two-photon fluorescence data on lipid membranes and live cells. I used this setup to study the near-field enhancement of optical fields near sharp metallic tips to increase the optical resolution of fluorescence images beyond the diffraction limit. From 2003 to 2006 I was a postdoctoral fellow at Sandia National Labs in Livermore, California. There I worked with Dr. Carl Hayden on development of a detection scheme to measure simultaneously the wavelength and the emission time of individiual photons. Our instrument provided fluorescence spectra and decays data at each pixel in a confocal image and allowed for an exquisite visualization of energy transfer (FRET) with single-molecule sensitivity.
Since 2006 I have been leading the Single-Molecule Biophysics Group at the University of Toronto Mississauga (UTM), in the Department of Chemical and Physical Sciences (CPS) and in the Graduate Department of Physics at University of Toronto. Since 2018 I am holding the rank of Full Professor, and between 2014 and 2019 I held the position of Department Chair of CPS. My research focuses on understanding protein conformations, interactions and dynamics primarily in the area of intrinsically disordered proteins (IDPs) and G-protein-coupled receptors (GPCRs), through the use of single-molecule fluorescence (SMF) spectroscopy. This type of research is innately interdisciplinary involving both instrumental and methods development, which requires Physics and Engineering background, and a systems focus, which requires expertise in Chemistry and Biology. In the past two decades, a multitude of single-molecule techniques have been developed and applied to a broad range of biological systems, including protein folding and disorder, molecular motors and ion channel electrophysiology. Single-molecule techniques can uniquely capture non-averaged molecular states and dynamics, and thus disentangle the complexity of biological systems.
My lab specializes in simultaneous measurements of multiple optical parameters from individual fluorescent labels in order to decipher the structural heterogeneity and dynamics of interacting macromolecules. Our powerful custom-built microscopes can measure nanometer scale intra- and inter-molecular distances and dynamics on the nanosecond to second timescales. This versatile multiparameter data is acquired at the level of single photons and is analyzed using custom software code developed in our lab. This continously improving suite of single-molecule spectroscopy instruments is unique in Canada and facilitiates many exciting local and international collaboration opportunities.