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.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.<graphic></graphic> [ABSTRACT FROM AUTHOR]