Chip-based SALDI-MS for rapid determination of intracellular ratios of glutathione to glutathione disulfide

Alterations in the ratio of glutathione (GSH) to glutathione disulfide (GSSG) reveal the cell living state and are associated with a variety of diseases. In this study, an Au NPs grafted nanoporous silicon chip was used for surface assisted laser desorption ionization-mass spectrometry (SALDI-MS) detection of GSH. Due to the bond interaction between thiol of GSH and Au NPs modified on the chip surfaces, GSH could be captured from the complex cellular lysate. Meanwhile, the composite nanostructures of Au NPs grafted porous silicon surface presented good desorption/ionization efficiency for GSH detection. The GSH levels in different tumor cells were successfully detected. Chip-based SALDI-MS was optimized for quantification of intracellular GSH/GSSG ratio changing under drug stimulation in liver tumor cells, GSSG was reduced to GSH by reductant of tris (2-carboxyethyl)phosphine (TCEP) and isotope-labeling GSH was as an internal standard. It was found that the increasing concentration of drug irinotecan and hypoxia culture condition caused the rapid consumption of GSH and a decrease of GSH/ GSSG ratio in liver tumor cells. The developed SALDI-MS method provided a convenient way to accurately measure and rapidly monitor cellular GSH value and the ratios of GSH/GSSG.