MoS 2 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 H 2 O 2 that was fabricated by covering molybdenum disulfide nanosheets (MoS 2 NS) with ortho-phenylenediamine (OPD). The probe (OPD-MoS 2 NS) was applied to the optical determination of H 2 O 2 , to the quantitation of cell numbers, and to the detection of intracellular concentrations of H 2 O 2 . Oxidation by H 2 O 2 leads to a colored and fluorescent product (oxidized OPD) with absorption/excitation/fluorescence peaks at 450/450/557 nm. The nanoprobe can detect H 2 O 2 in down to 500 nM concentrations, and HeLa cells at levels of 100 cells mL −1 . The detection limit for intracellular H 2 O 2 is in the 5.5 to 12.6 μM concentration range when the method is applied to cells at levels of 10 2 –10 6 cells mL −1 . Due to its good biocompatibility and easy cell uptake, the nanoprobe also permits sensitive fluorometric imaging of intracellular H 2 O 2 . 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 MoS 2 nanosheets is used to quantitatively detect H 2 O 2 , cell numbers and intracellular H 2 O 2 . The MoS 2 nanoprobes also permit sensitive fluorescence imaging of intracellular H 2 O 2 , and can discriminate intracellular oxide states in living cancerous and normal cells.