Single-Molecule Sensing By Grating-Based Spectrally Resolved Super-Resolution Microscopy

Recent advances in single-molecule spectroscopic imaging techniques, such as spectrally resolved stochastic optical reconstruction microscopy (SR-STORM), have been effective for obtaining detailed spectral information at the molecular level. However, its application for single-molecule sensing is highly challenging owing to its complicated configuration and limited spectral information. In this study, we demonstrated single-molecule polarity sensing by combining grating-based SR-STORM with the solvatochromic dye, Nile red. The spatial and spectral resolutions of the custom-built grating-based SR-STORM were examined for various color ranges of fluorescent dyes, and this approach was successfully applied for sensing nanoscale local polarity of various organic solvent molecules and surfactant molecules. Furthermore, we demonstrated that the proposed method effectively distinguished the different polarities of functional groups within surfactant molecules at the single-molecule level. We anticipate that the proposed approach can be combined with other chromic molecules for application to many other chemical systems.