High-speed, high-content, label-free live-cell chemical imaging in multiwell plates using photothermal stimulated raman scattering (PT-SRS) microscopy

The National Institute of General Medical Sciences awarded Photothermal Spectroscopy Corp. $306,802 on September 1, 2026, under the Biomedical Research and Research Training program (CFDA 93.859) to develop a next-generation photothermal stimulated Raman scattering (PT-SRS) microscope for high-speed, label-free chemical imaging of live cells in standard multiwell culture plates.

Current PT-SRS implementations use transmission geometries that prevent compatibility with inverted microscopes and 96-well plate formats standard in modern cell biology. Photothermal Spectroscopy will demonstrate feasibility of the first epi-detected PT-SRS platform on an inverted microscope, eliminating the need for specialized substrates or complex sample handling. The approach integrates three co-aligned beams (pump, Stokes, and probe) with optimized detectors to achieve robust sensitivity, high spatial resolution, and biologically safe power levels.

Specific Aim 1 will establish technical feasibility by assembling the optical system, validating pointing stability, and characterizing sensitivity, resolution, and signal-to-noise using chemical standards and calibration beads. Specific Aim 2 will demonstrate biological feasibility by acquiring lipid and protein vibrational images of live cells in 96-well plates.

The award is classified as a Phase I Small Business Innovation Research (SBIR) project grant. Performance occurs in Santa Barbara, California, with a period of performance from September 1, 2026, through August 31, 2027.

Abstract

Photothermal spectroscopy corp. Proposes to develop a next-generation photothermal stimulated raman scattering (PT-SRS) microscope designed for compatibility with standard life sciences workflows. Raman microscopy provides powerful label-free chemical specificity, but current implementations are too slow, insensitive, or incompatible with common formats such as 96-well plates, severely limiting their use in live-cell and high-throughput studies. PT-SRS, recently demonstrated at boston university and licensed to photothermal, overcomes key limitations of conventional SRS and cars by detecting vibrationally selective heating with high sensitivity and spectral fidelity. However, existing PT- SRS implementations are constrained to transmission geometries, preventing use with inverted microscopes and multiwell culture plates-the dominant formats in modern cell biology. In this phase i sbir project, we will demonstrate feasibility of the first EPI-detected PT-SRS platform on an inverted microscope, enabling high-speed, label-free chemical imaging directly from standard well plates and live-cell cultures. This advance eliminates the need for specialized substrates or complex sample handling, creating a practical, accessible tool for life sciences research. The approach integrates three CO-aligned beams (pump, stokes, and probe) with optimized detectors to achieve robust sensitivity, high spatial resolution, and biologically safe power levels. Specific aim 1 will establish technical feasibility: assembling the optical system, validating pointing stability, and characterizing sensitivity, resolution, and signal-to-noise using chemical standards and calibration beads. Specific aim 2 will demonstrate biological feasibility: acquiring lipid and protein vibrational images of live cells in 96-well plates, confirming cell viability after repeated imaging, and showing high-throughput operation. There is currently no commercially available instrument that enables high-content, label-free chemical imaging of live cells in standard culture formats. Meeting this need will advance NIH priority areas in translational research by providing an accessible platform for drug discovery, antimicrobial resistance studies, metabolic profiling, and spatial biology. The project is enabled by a team with extensive experience in commercializing breakthrough vibrational spectroscopies (AFM-IR, o-ptir), developing advanced confocal and laser scanning microscopy platforms now standard in life sciences, and pioneering SRS and live-cell chemical imaging methods. Additional expertise in systems engineering, opto- mechanical design, and instrument control software ensures technical execution and a clear path to commercialization. Successful completion of phase i will yield a validated EPI-PT-SRS prototype demonstrating both technical and biological feasibility. This will lay the foundation for a fully engineered PT-SRS system in phase II, application-driven demonstrations, and market entry. By enabling rapid, label-free chemical imaging in standard culture formats, the platform has strong potential to accelerate high-content drug screening, antimicrobial susceptibility testing, and metabolomic and spatial biology studies-areas of direct importance to NIH's mission and to advancing human health.