High sensitivity and non-background SERS detection of endogenous hydrogen sulfide in living cells using core-shell nanoparticles.

Endogenous hydrogen sulfide (HS) exists in multiple physiological processes. In order to further understand the action mechanism of HS in cells and human body, we proposed a smart surface-enhanced Raman scattering (SERS) nanoprobe, Au core-4-mercaptobenzonitrile-Ag shell nanoparticle (Au@4-MBN@Ag), for the detection of endogenous HS in living cells based on the reaction between Ag shell and sulfide species. 4-MBN was selected as the SERS reporter to avoid interference from cellular molecules. With the sulfide concentration increasing, the AgS constantly formed, and consequently the SERS signal intensity of Au@4-MBN@Ag gradually decreased owing to the weaker SERS activity of AgS. With the nanoprobes, this method not only offers a high sensitivity for HS detection at an nM level, but also achieves the goal of non-background analysis. It displays satisfactory anti-interference capability and a good linear relationship with sulfide concentration ranging from 50 nM to 500 μM, and an estimated detection limit is 0.14 nM. The Au@4-MBN@Ag nanoprobes were successfully applied to detect endogenous HS in living HepG2 cells stimulated by pyridoxal 5-phosphate monohydrate. This work offers a potential analytical method in the related research of HS physiological function.