2D Materials Assisted Nanoscopic Mapping of Proton fluxes in living cells

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Proton channels in cells and the corresponding transmembrane proton fluxes are critical for many cell activities. Recent studies reveal that expression levels of proton channel Hv1 and its activity are highly associated with the development of many diseases, including cancer spreading, disrupted bone metabolism, and stroke, which makes proton channel an interesting therapeutic target. Yet, the full understanding of the mechanism of proton flux-related disease development is still under development partially due to a lack of direct observation method of the proton fluxes in living cells with high spatiotemporal resolution. To tackle this issue, we propose to develop a high throughput label-free super-resolution imaging method to map proton fluxes in cells by using two-dimensional hexagonal Boron Nitride (hBN) substrate with proton-activated emitters. Very recently, my colleague and I found that surface defects in hBN can be optically activated by protonation in aqueous solutions resulting in intermittent emission that allows single-molecule localization analysis. The high photocounts from the emitters lead to localization with precision as high as 7 nm. Using such surface defects as an array of proton sensors, proton fluxes from proton channels in cell membranes in close proximity can be detected label-free. In this project, we will (1) artificially introduce and characterize defects in hBN that are optimized for proton sensing purposes; (2) test the photophysics of defect emitter in physiological conditions; (3) demonstrate proof-of-the-concept super-resolved mapping of Hv1 proton channel activities in vivo and in vitro. Via this project, I will further develop my core competence in 2D materials, single-molecule sensing, microscopy and more importantly learn to design and handle experiments of the complex biological systems and bio-imaging in the host group. This fellowship will greatly improve my competence to pursue an academic career in the bio-sensing field.