Photoswitchable vibrational nanoscopy with sub-100-nm optical resolution
Jianpeng Ao, Xiaofeng Fang, Liyang Ma, Zhijie Liu, Simin Wu, Changfeng Wu, Minbiao Ji
Abstract
Stimulated Raman scattering (SRS) microscopy has shown superior chemical resolution due to the much narrower vibrational spectral bandwidth than its fluorescence counterpart. However, breaking the diffraction-limited spatial resolution of SRS imaging is much more challenging because of the intrinsically weak scattering cross section and inert/stable nature of molecular bond vibrations. We report superresolution SRS (SR-SRS) nanoscopy based on reversible-switchable vibrational photochromic probes integrated with point spread function engineering strategy. By introducing a Gaussian-shaped ultraviolet excitation beam and a donut-shaped visible depletion beam in addition to the pump and Stokes beams, SR-SRS could reach sub-100 nm resolution on photoswitchable nanoparticles (NPs). Furthermore, NP-treated live cell imaging was demonstrated with resolution improvement by a factor of ∼4. Our proof-of-principle work provides the potential for SR vibrational imaging to assist research on complex biological systems.