Quencher-Enhanced Raman Scattering Probes With Large Scattering Cross-Section for NIR-II Surgical Navigation and...

Since the discovery of unique molecular building blocks (MBBs) such as tetraphenylethylene, aggregation-induced emission fluorescence imaging probes have witnessed revolutionary progress. For plasmon-free Raman imaging probes, the fundamental bottleneck is the discovery of unique Raman-active MBBs to improve the intrinsic scattering. We herein proposed a new concept of quencher-enhanced Raman scattering (QERS) based on nonfluorescent diammonium MBBs to fabricate bright Raman probes in second near-infrared window through improving rigid electronic resonance scattering while simultaneously suppressing concomitant fluorescence backgrounds. The home-made large π-conjugated diammonium quencher displays high photon-absorption but ultra-low fluorescence quantum yield (0.0001) under rigid resonant excitation at 1064 nm. Upon nanoprecipitation, these MBBs produce QERS probes with giant Raman cross-section (1.27 × 10^-19 cm²) as well as remarkable photostability, enabling high-precision Raman-guided surgical removal of tumor in living mice. Moreover, QERS probes achieve a high photothermal conversion efficiency up to 60.5%, allowing for effective hyperthermia ablation of drug-resistant bacteria in postsurgical infected wounds in the mice. QERS may suggest a robust and efficient strategy for developing plasmon-free Raman probes.