Quantitative detection and cellular imaging of hydrogen sulfide using a SERS probe based on AuAg nanocages

Hydrogen sulfide (H₂S), a crucial gasotransmitter, plays an essential regulatory role in various physiological and pathological processes. There is an urgent need to develop sensitive and effective detection methods for intracellular H₂S, as abnormal H₂S levels are closely related to various diseases such as tumors. Herein, a surface-enhanced Raman scattering (SERS) probe was constructed for quantitative detection and imaging of H₂S in living cells. The SERS probe was obtained by using gold silver alloy nanocages (AuAg NCs) with superior plasmonic activity as SERS substrate, followed by modification with Raman signal molecule (4-ethynylaniline), mucin1 aptamer and polyethylene glycol. Upon exposure to H₂S, Ag in the SERS probe was rapidly and specifically converted to Ag₂S, leading to a remarkable decrease in the SERS intensity of the probe at 2010 cm^-1, a spectral region within the cell silent region. The developed SERS probe exhibited outstanding performances, including high sensitivity (with a detection limit as low as 0.36 nM for H₂S), remarkable selectivity, excellent stability and minimal cytotoxicity. Notably, this SERS probe had been successfully applied for the detection and imaging of both endogenous and exogenous H₂S levels in single living cells without bio-interference, highlighting its potential for precise and accurate intracellular H₂S monitoring. This advancement provides a powerful tool for studying H₂S-related physiological processes and disorders.