Noninvasive and Highly Multiplexed Five-Color Tumor Imaging of Near-Infrared Resonant Surface-Enhanced Raman Nanoparticles In Vivo

In vivo multiplexed imaging aims for noninvasive analysis of multiple tumor biomarkers. While most of the preclinical imaging has provided a number of multiplexing channels up to three, Raman imaging with surface-enhanced Raman scattering (SERS) nanoparticles was suggested to offer higher multiplexing capability originating from their narrow spectral width. However, the multiplexed Raman imaging is still in its infancy for visualizing tumors with both sufficient multiplicity and high sensitivity concurrently. Here we create multispectral palettes of gold core-near-infrared (NIR) resonant Raman dyes-silica shell SERS (NIR-SERRS) nanoparticles, which provide both the high multiplicity and fluorescence-comparable sensitivity. With the NIR-SERRS nanoparticle palettes, we demonstrate noninvasive and five-plex ratiometric Raman imaging of tumors in living mice. Furthermore, we perform noninvasive and longitudinal imaging of the five-color nanoparticles in the tumors, which is not feasible with current ex vivo multiplexing platforms, demonstrating great potential for noninvasive assessment of multiple biological targets within tumors.