期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2016
卷号：113
期号：37
页码：10364-10369
DOI：10.1073/pnas.1611038113
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：Two long-standing problems for superresolution (SR) fluorescence microscopy are high illumination intensity and long acquisition time, which significantly hamper its application for live-cell imaging. Reversibly photoswitchable fluorescent proteins (RSFPs) have made it possible to dramatically lower the illumination intensities in saturated depletion-based SR techniques, such as saturated depletion nonlinear structured illumination microscopy (NL-SIM) and reversible saturable optical fluorescence transition microscopy. The characteristics of RSFPs most critical for SR live-cell imaging include, first, the integrated fluorescence signal across each switching cycle, which depends upon the absorption cross-section, effective quantum yield, and characteristic switching time from the fluorescent “on” to “off” state; second, the fluorescence contrast ratio of on/off states; and third, the photostability under excitation and depletion. Up to now, the RSFPs of the Dronpa and rsEGFP (reversibly switchable EGFP) families have been exploited for SR imaging. However, their limited number of switching cycles, relatively low fluorescence signal, and poor contrast ratio under physiological conditions ultimately restrict their utility in time-lapse live-cell imaging and their ability to reach the desired resolution at a reasonable signal-to-noise ratio. Here, we present a truly monomeric RSFP, Skylan-NS, whose properties are optimized for the recently developed patterned activation NL-SIM, which enables low-intensity (∼100 W/cm2) live-cell SR imaging at ∼60-nm resolution at subsecond acquisition times for tens of time points over broad field of view.
