Facile and sensitive measurement of GSH/GSSG in cells by surface-enhanced Raman spectroscopy

Reduced glutathione (GSH) and the oxidized glutathione (GSSG) are well-known biomolecules in the main constituents of intracellular redox homeostasis system. A rapid, accurate measurement of cellular GSH and GSSG is quite needed in investigating important biochemical events. In this work, we present a novel and sensitive method to monitor intracellular GSH and GSSG concentrations by a portable surface-enhanced Raman spectroscopy (SERS) technique. We introduced a reduction-sensitive reaction-type Raman probe, 5,5'-dithiobis-(2-nitrobenzoic acid) (DTNB) to initiate GSH reduction, itself concomitantly converts to 2-nitro-5-thiobenzoic acid (TNB) to release a strong SERS signal. In a convenient way of inorganic salt MgSO₄ induced aggregation of silver nanoparticles substrate, we easily implemented a good discrimination between DTNB and TNB, and a quantitative measurement of GSH and GSSG with a high sensitivity of 10 nM. This SERS method proved its feasible applicability in rapidly and sensitively monitoring GSH depletion behaviors of some notorious alkylating agents, i.e., sulfur mustard and nitrogen mustards in ex vitro or in vitro (cellular response). This SERS method may be very worthwhile in cellular detoxication event via the GSH approach and other GSH involved biomedical researches.