Dynamic Detection of Endogenous Hydroxyl Radicals at Single-Cell Level with Individual Ag-Au Nanocages.

Hydroxyl radicals (•OH) is a type of short-lived radicals which is the most aggressive reactive oxygen species due to its high reac-tivity to biomolecules. Dynamic measurement of •OH level in living cells is critical for understanding cell physiology and patholo-gy. In this manuscript, we prepare individual Ag-Au@PEG/RGD nanocages for in-situ determination of endogenous •OH at single-cell level, whose spectral shift rate correlate to the •OH concentration. The high-selective response to •OH relies on the specific oxidization of the conjugated PEG/RGD outside and the silver etching inside the nanocages that resulted in a significant LSPR signal and scattered color changes. The spectral red-shift rate of LSPR has a linear relationship with the logarithm of •OH concen-tration in range of 100 pM to 1 μM, suitable for the measurement of endogenous •OH. Thus, the individual nanocages were suc-cessfully used to monitor the dynamic intracellular •OH level of single tumor cells under oxidative stress. This strategy has great potential in promoting •OH mediated cell homeostasis and injury research.