Bifunctional Mo/V-polyoxometalates in mimicking peroxidase/sarcosine oxidase for simultaneously detecting H2O2 ans sarcosine via colorimetry

Polyoxometalates (POMs) containing Mo and V were Hn+3PMo12-nVnO40 (n = 1, 2, 3, 4, 5, 8, abbreviated as PMo12-nVn) evaluated in mimicking peroxidase (POD) and sarcosine oxidase (SOD) performances. The mechanism studies revealed that the POD-like activity was coherent with the redox properties of Mo/V POMs, which existence of H+ participated the electron transfer (ET) as proton-couple electron transfer (PCET) process to activate H2O2 to ·OH undergoing Fenton-like procedure. Among PMo4V8 exhibited highest POD-like activity, which Km and Vmax were tested to be 5.814 μM and 8.065 μM·min-1 in the reaction of H2O2 with 3,3′,5,5′-tetramethylbenzidine (TMB). Meanwhile, PMo4V8 also exhibited excellent SOD-like activity to catalyze oxygen to oxidize sarcosine generating H2O2, glycine and formaldehyde, which could be detected by the color changes of TMB from white to blue (TMBox) in quality and quantity with UV-vis spectroscopy and naked eyes. Mo-V POMs provided a innovative and a new alternative technique to replace peroxidase and sarcosine oxidase in simultaneously detection of H2O2 and sarcosine with other lower detection limits (LOD) as 10.0-30.0 μM and 9.123 μM, respectively, which could be applied in detecting sarcosine in urine without any complex pretreatment in other measurements with good availability.