SERS nanoprobes for the monitoring of endogenous nitric oxide in living cells

Nitric Oxide (NO) is a significant gaseous signalling molecule in various pathological and physiological pathways, whereas many of its functions are still ambiguous in part because of the shortage of powerful detection approaches. Herein, we present a type of reaction-based surface-enhanced Raman scattering (SERS) nanoprobes, o-phenylenediamine-modified gold nanoparticles (AuNPs/OPD), to detect the level of the endogenous NO in living cells. The detection is achieved through the SERS variation of AuNPs/OPD caused by the reaction between NO and OPD on the surface of AuNPs. The proposed SERS nanoprobes have a good stability and a rapid response to NO within 30 s Moreover, as a result of the reaction specificity coupled with SERS fingerprinting, AuNPs/OPD nanoprobes demonstrate high selectivity towards NO over other biologically relevant species with a sensitivity at 10^-7 M level. Thereby, this SERS strategy can be used for monitoring NO that is endogenously produced in living macrophages, indicating immense potential in studying NO-involved pathophysiological processes in biological systems.