Plasmon-enhanced stimulated Raman scattering microscopy with single-molecule detection sensitivity

Area of Science:

• Chemical Imaging
• Biomedical Optics
• Spectroscopy

Background:

• Stimulated Raman scattering (SRS) microscopy offers high-speed, label-free chemical imaging for biological applications.
• Current SRS sensitivity is limited to micromolar concentrations for endogenous molecules, hindering single-molecule detection.
• Existing methods struggle with the extremely small Raman cross-sections of single biomolecules.

Purpose of the Study:

• To develop a plasmon-enhanced stimulated Raman scattering (PESRS) microscopy technique.
• To achieve single-molecule detection sensitivity for label-free chemical imaging.
• To demonstrate the application of PESRS for mapping biological molecular events.

Main Methods:

• Development of plasmon-enhanced stimulated Raman scattering (PESRS) microscopy.
• Integration of pico-Joule laser excitation, background subtraction, and denoising algorithms.
• Verification of single-molecule detection using adenine isotopologues and temporal domain analysis (blinking/bleaching).

Main Results:

• Achieved robust single-pixel SRS spectra with single-molecule event detection.
• Demonstrated single-molecule sensitivity using PESRS microscopy.
• Successfully mapped adenine release from bacteria under starvation stress.

Conclusions:

• Plasmon-enhanced stimulated Raman scattering (PESRS) microscopy enables unprecedented single-molecule detection sensitivity.
• PESRS overcomes the limitations of conventional SRS for ultrasensitive molecular imaging.
• PESRS holds significant promise for rapid, label-free mapping of molecular events in chemical and biomedical fields.