Au/Ag Nanobox-Based Near-Infrared Surface-Enhanced Raman Scattering for Hydrogen Sulfide Sensing

Hydrogen sulfide (H₂S) is a gaseous signaling agent that has important regulatory roles in many biological systems but remains difficult to measure in living biological specimens. Herein, we report a novel near-infrared (NIR) activated surface-enhanced Raman scattering (SERS) nanosensor for in vitro and in vivo H₂S assay utilizing Au/Ag alloy nanoboxes with local surface plasmon resonance (LSPR) at 741 nm. This detection is realized by SERS spectrum changes of the NIR probes, which are labeled on Au/Ag nanoboxes under NIR laser irradiation, resulting from the reaction of H₂S with Ag in the substrate of Au/Ag nanoboxes. Owing to the well-matching between the incident laser light frequency and the LSPR of the substrates at the NIR region, this SERS nanosensor with a high selectivity and sensitivity can be utilized to monitor the distribution of H₂S in living cells and zebrafish embryos. Noticeably, the NIR SERS signal is detectable in tissues at depths of up to 12 mm, demonstrating its huge potential in the in vivo studies of pathophysiological processes involving H₂S.