A sensitive probe for detecting intracellular reactive oxygen species via glutathione-mediated nanoaggregates to enhance Resonance Rayleigh scattering signals

Development of rapid and, facile assays for quantification and evaluation of intracellular reactive oxygen species (ROS) activity in cancerous cells is of great importance to clinical diagnosis and therapeutic monitoring. Here, a straightforward, sensitive and quantitative assay for cytosensing and biodetecting of ROS from normal and cancerous cells were designed by taking advantage of targeted nanoprobes and size-sensitive Resonance Rayleigh scattering (RRS) technique for the first time. Using glutathione (GSH)-modified gold nanoparticles as nanoprobes, the constructed ROS-activated GSH dimerization, GSH disulfides-triggered interparticles couplings and nanoprobe-aggregation-assisted RRS signal amplification are used for improving selectivity and sensitivity. Fenton reaction-based RRS measurements enabled a sensitively signal enhancement in detection after introduction of FeCl2, and the detection limit of H2O2 was calculated to be 51.0 nM. GSH-targeted RRS cytosensor was further applied in quantitatively detecting human breast cancer HepG2 cell and normal cells, by recognizing changes in GSH dimerization from different cell types. The detection limit for HepG2 cells was 25 cells/mL and the intracellular ROS amount of 0.05-0.20 μM in 100-1000 cells/mL could be calculated with good selectivity and reproducibility. This assay demonstrates its potential in clinical diagnostic and therapeutic monitoring.