Stanford Advisors

All Publications

  • Application of electrochromic thin films for electrophysiology Alfonso, F., McGuire, A., Li, T., Santoro, F., Cui, B. AMER CHEMICAL SOC. 2018
  • Application of Electrochromic Thin Films for Electrophysiology Felix Alfonso Alfonso, F. CELL PRESS. 2018: 671A
  • Full-field interferometric imaging of propagating action potentials. Light, science & applications Ling, T., Boyle, K. C., Goetz, G., Zhou, P., Quan, Y., Alfonso, F. S., Huang, T. W., Palanker, D. 2018; 7: 107


    Currently, cellular action potentials are detected using either electrical recordings or exogenous fluorescent probes that sense the calcium concentration or transmembrane voltage. Ca imaging has a low temporal resolution, while voltage indicators are vulnerable to phototoxicity, photobleaching, and heating. Here, we report full-field interferometric imaging of individual action potentials by detecting movement across the entire cell membrane. Using spike-triggered averaging of movies synchronized with electrical recordings, we demonstrate deformations up to 3nm (0.9mrad) during the action potential in spiking HEK-293 cells, with a rise time of 4ms. The time course of the optically recorded spikes matches the electrical waveforms. Since the shot noise limit of the camera (~2mrad/pix) precludes detection of the action potential in a single frame, for all-optical spike detection, images are acquired at 50kHz, and 50 frames are binned into 1ms steps to achieve a sensitivity of 0.3mrad in a single pixel. Using a self-reinforcing sensitivity enhancement algorithm based on iteratively expanding the region of interest for spatial averaging, individual spikes can be detected by matching the previously extracted template of the action potential with the optical recording. This allows all-optical full-field imaging of the propagating action potentials without exogeneous labels or electrodes.

    View details for PubMedID 30564313

  • Redesign of a Pyrylium Photoredox Catalyst and Its Application to the Generation of Carbonyl Ylides. Organic letters Alfonzo, E., Alfonso, F. S., Beeler, A. B. 2017; 19 (11): 2989-2992


    We report the exploration into photoredox generation of carbonyl ylides from benzylic epoxides using newly designed 4-mesityl-2,6-diphenylpyrylium tetrafluoroborate (MDPT) and 4-mesityl-2,6-di-p-tolylpyrylium tetrafluoroborate (MD(p-tolyl)PT) catalysts. These catalysts are excited at visible wavelengths, are highly robust, and exhibit some of the highest oxidation potentials reported. Their utility was demonstrated in the mild and efficient generation of carbonyl ylides from benzylic epoxides that otherwise could not be carried out by current common photoredox catalysts.

    View details for DOI 10.1021/acs.orglett.7b01222

    View details for PubMedID 28530103