Widefield bond-selective super-resolution microscopy by SIM-based mid-infrared photothermal imaging

Recently, there has been a growing effort to integrate molecular information into the flourishing fluorescence microscopy community. A notable approach involves utilizing molecular-bond-specific absorption in the mid-infrared window to modulate fluorescence emission, thereby facilitating the extraction of chemical bond distributions in complex specimens. Here, we propose a scheme to surpass the diffraction limited spatial resolution in a high-speed, widefield manner, utilizing the advantages of employing a fluorescence readout. We leverage the high-speed, wide-field imaging capabilities of structured illumination microscopy (SIM) in conjunction with mid-infrared photothermal (MIP) imaging to showcase high-fidelity spectroscopic capabilities. The experimental results of spectroscopic super-resolution imaging further underscore the potential of molecular bond-selective techniques for advancing mainstream fluorescence microscopy in the life sciences and biomedicine.