Visualizing the Interactions between Individual Molecules within Cell Membranes Using Chemical Probes, Computation, and Microscopy
The membrane of a cell separates its internal contents, such as organelles, DNA, and proteins, from its environment and therefore controls how chemical signals (e.g., molecules) are sent to and received from other cells. Existing imaging technologies struggle to visualize the nanoscale "wrinkles" and roughness of these membranes due to their small sizes and fast fluctuations. This project will develop a synergistic approach called computational single-molecule nanoscopy that combines optical hardware, image processing software, and molecular sensors for imaging living cells with nanoscale resolution. The proposed technology will visualize the electrical and chemical environments within membranes that govern how they work. Ultimately, this approach will enable scientists to study how nanoscale structures within the membrane influence how molecules are transported across the membrane, which could be useful for the design of nanomedicines that target and kill cancer cells. The PI will collaborate with the Saint Louis Science Center and the Washington University SPECTRA student group to promote the public's scientific and technological understanding of this research. Undergraduate and graduate students involved in the research program will obtain broad knowledge and diverse technical skills in applied physics, optics, spectroscopy, estimation theory, image processing, and biology. These students will receive a unique and comprehensive preparation for modern careers in technology innovation and scientific discovery.
The proposed research will develop an integrated chemical, optical, and computational technology, termed computational single-molecule nanoscopy, for sensing and imaging the electrical and chemical properties of cell membranes with nanoscale resolution. The research approach is 1) to investigate the resolution and sensitivity limits of computational optical nanoscopy for measuring nanoscale information; 2) to quantify the performance of fluorescent molecules for sensing the electrical and chemical properties of their nano-environments; and 3) to visualize lipid rafts within cell membranes to determine how they regulate the trafficking of biomolecules across the membrane. The merit of the proposed work lies in innovatively exploiting the synergy between fluorescent molecules and optical microscopes. Rather than simply using fluorescent molecules as beacons that report a biomolecule's location, as current methods do now, the fluorescence emitted by rapidly-diffusing molecules will be used to measure the polarity and fluidity of a nano-environment. To harness the information reported by these molecules, new optical systems and image processing algorithms will be jointly designed to maximize the precision and sensitivity of nanoscale measurements in the presence of noise. Sensing the nanoscale properties of cell membranes will provide new insight into intercellular communication: how electrical, chemical, and mechanical signals propagate between cells and across their membranes.
