Two dimensional a-MoO^sub 3-x^ nanoflakes as bare eye probe for hydrogen peroxide in biological fluids

We report a rapid and facile method for detection of hydrogen peroxide (H2O2) in biological fluids using sub-stoichiometric two-dimensional (2D) molybdenum trioxide (α-MoO3-x) nanoflakes. The two-dimensional nanoflakes, initially blue in color, is oxidized after interaction with hydrogen peroxide thereby changing its oxidation state to form α-MoO3. The change in oxidation state of nanoflakes transforms from blue to a visually distinct hazy blue color with change in absorption spectrum. The phenomenal property is explored here in sensing up to 34 nM as limit of detection. The efficacy of the detection system was analyzed by “zone of inhibition” based agar diffusion assay with different concentrations of H2O2. The current approach is highly accurate, effective and reproducible for quantification of physiological concentration of H2O2 in biological fluid such as human urine.