Highly Biocompatible Super-resolution Imaging: SPoD-OnSPAN

Abstract

Super-resolution microscopy facilitates observation with an optical microscope at a higher spatial resolution than the diffraction limit of light; however, super-resolution observation with high biocompatibility remains challenging. Leading super-resolution techniques such as reversible saturable/switchable optical fluorescence transition (RESOLFT) and single-molecule localization microscopy (SMLM) need to illuminate a sample at an appreciably high power density of illumination, i.e., from 0.1 kW/cm² to 1 GW/cm². Unfortunately, that high power density gives rise to phototoxicity in live cells, and this may prevent widespread use of super-resolution imaging in the life sciences. In this study we show a technique of super-resolution imaging that can be performed at a very low power density of illumination, SPoD-OnSPAN (super-resolution polarization demodulation/on-state polarization angle narrowing). This achieves super-resolution observations at a power density as low as 1 W/cm², and thereby high biocompatibility. The present technique is likely to be very useful for situations such as time-lapse super-resolution observations of live cells and tissues.