Super-resolution stimulated Raman Scattering microscopy with A-PoD

Abstract

Unlike traditionally-mapped Raman imaging, stimulated Raman scattering (SRS) imaging achieved the capability of imaging metabolic dynamics and a greatly improved signal-noise-ratio. However, its spatial resolution is still limited by the numerical aperture or scattering cross-section. To achieve super-resolved SRS imaging, we developed a new deconvolution algorithm - Adam optimization-based Pointillism Deconvolution (A-PoD) - for SRS imaging, and demonstrated a spatial resolution of 52 nm on polystyrene beads. By changing the genetic algorithm to A-PoD, the image deconvolution process was shortened by more than 3 orders of magnitude, from a few hours to a few seconds. By applying A-PoD to spatially correlated multi-photon fluorescence (MPF) imaging and deuterium oxide (D2O)-probed SRS (DO-SRS) imaging data from diverse samples, we compared nanoscopic distributions of proteins and lipids in cells and subcellular organelles. We successfully differentiated newly synthesized lipids in lipid droplets using A-PoD coupled with DO-SRS. The A-PoD-enhanced DO-SRS imaging method was also applied to reveal the metabolic change in brain samples from Drosophila on different diets. This new approach allows us to quantitatively measure the nanoscopic co-localization of biomolecules and metabolic dynamics in organelles. We expect that the A-PoD algorithm will have a wide range of applications, from nano-scale measurements of biomolecules to processing astronomical images.