Fig. 5

High-speed and high-contrast wide-area Raman imaging. a Schematic illustration of the stepping scan mode for high-speed cell Raman imaging. b Bright-field image, c Raman image, and d the overlay image of a single H1299 cell. The Raman image is obtained within 6 s (50 × 50 pixels) with a laser power of 370 μW and a 0.7 ms acquisition time per pixel. Scale bars in panel b–d are 10 μm. e Three representative SERS spectra obtained from different points in panel c. f Schematic illustration of the Macro scan mode for wide-area tissue imaging. (g, h) High-contrast and wide-area in vivo Raman image (3.2 × 2.8 cm²) of the hind-limb popliteal lymph node after injection of P-GERTs. The Raman image was obtained within 52 s (20 × 20 pixels) with a laser power of 370 μW and acquisition time of 0.7 ms per pixel. Scale bars in panel g and h are 1 cm. The inset in h shows Raman spectra at the SLN in situ (point 2), adjacent tissue (point 1) and surrounding environment (point 3). All Raman images are plotted using the Raman band at 1340 cm⁻¹. The intensity and signal-to-background ratio (SBR) of the Raman signal (1340 cm⁻¹) cross-section from top to bottom marked by the white dashed line in h (i) before and j after the baseline correction of Raman spectra