MoS2 nanosheets with peroxidase mimicking activity as viable dual-mode optical probes for determination and imaging of intracellular hydrogen peroxide.

The authors describe a dual-mode (colorimetric-fluorometric) nanoprobe for H2O2 that was fabricated by covering molybdenum disulfide nanosheets (MoS2 NS) with ortho-phenylenediamine (OPD). The probe (OPD-MoS2 NS) was applied to the optical determination of H2O2, to the quantitation of cell numbers, and to the detection of intracellular concentrations of H2O2. Oxidation by H2O2 leads to a colored and fluorescent product (oxidized OPD) with absorption/excitation/fluorescence peaks at 450/450/557 nm. The nanoprobe can detect H2O2 in down to 500 nM concentrations, and HeLa cells at levels of 100 cells mL-1. The detection limit for intracellular H2O2 is in the 5.5 to 12.6 μM concentration range when the method is applied to cells at levels of 102-106 cells mL-1. Due to its good biocompatibility and easy cell uptake, the nanoprobe also permits sensitive fluorometric imaging of intracellular H2O2. It can also comparatively discriminate the change of intracellular oxidation state in living cancerous and normal cells. Graphical abstract Editor, we provided image with high resolution. Please find it in a folder name "MIAC-D-18-00081" in the FTP site. A dual-mode (colorimetric-fluorometric) detection nanoplatform based on OPD-modified MoS2 nanosheets is used to quantitatively detect H2O2, cell numbers and intracellular H2O2. The MoS2 nanoprobes also permit sensitive fluorescence imaging of intracellular H2O2, and can discriminate intracellular oxide states in living cancerous and normal cells.