Vanadium‐Substituted Tungstosulfate Polyoxometalates as Peroxidase Mimetics and Their Potential Application in Biosensing

This article reports on the peroxidase‐like catalytic activity of polyoxometalates (POMs) and their potential use as natural peroxidases for developing a simple and efficient colorimetric glucose sensor. Two Keggin‐type vanadium‐substituted tungstosulfates, [SVW11O40]3− (SVW11) and [SV2W10O40]4− (SV2W10), were tested for their potential as natural enzyme mimetics and exhibited strong peroxidase‐like catalytic activity. The catalysis reaction was found to be in accordance with Michaelis‐Menten and Lineweaver‐Burk kinetics models. Michaelis‐Menten constant (Km) and maximum velocity (Vmax) parameters were calculated to be 0.0759 mM and 0.329×10−8 Ms−1 for SVW11, and 0.0543 mM and 2.67×10−8 Ms−1 for SV2W10, respectively, indicating a high catalytic activity and a strong affinity of POMs towards 3,3,5,5‐tetramethylbenzidine (TMB). In the case of H2O2, these values were found to be 57.1 mM and 0.325×10−8 mMs−1 for SVW11, and 47.7 mM and 2.72×10−8 mMs−1 for SV2W10. The peroxidase‐like catalytic activity of these POMs was used to develop colorimetric glucose sensors as a proof‐of‐concept model for the POM‐based naked‐eye detection of biomolecules. The limit of detcetion (LOD) of glucose for SVW11 and SV2W10 was 1.14 μM and 1.24 μM, respectively. Our findings propose broad‐ranging potential applications of these novel POMs in biosensing and bioanalytical chemistry.