Operando characterization of chemical reactions in single living cells using SERS.

Detection of chemical reactions in living cells is critical in understanding physiological metabolic processes in the context of nanomedicine. Carbon monoxide (CO) is one of the important gaseous signaling molecules. Surface-enhanced Raman spectroscopy (SERS)-based CO-releasing nanoparticles (CORN) is utilized to investigate the chemical reaction of CO delivery in live cells. Using SERS CORN, carbonyl dissociation from CORN-Ag-CpW(CO)3 to CORN-Ag-CpW(CO)2 in live cells is observed. The subsequent irreversible degradation to CO-free CORN is a consequence of oxidative stress in cells. This observation affirms the step transition of CORN-Ag-CpW(CO)3 in cellular: CORN-Ag-CpW(CO)3 first proceeds via a direct loss of one CO followed by a oxidative decomposition giving rise to CORN-Ag-WO3 and as well as the release of one equivalents of CO. Importantly, the decarbonylation process can be correlated with the level of inflammatory biomarkers. For the first time, we provide unambiguous evidence for the steps transition of CO-release mechanism in cellular.