Layered perovskites have been extensively investigated in many research fields, such as electronics, catalysis, optics, energy, and magnetics, because of the fascinating chemical properties that are generated by the specific...
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, [SVW 11 O 40 ] 3À (SVW 11) and [SV 2 W 10 O 40 ] 4À (SV 2 W 10), 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 (K m) and maximum velocity (V max) parameters were calculated to be 0.0759 mM and 0.329 × 10 À 8 Ms À 1 for SVW 11 , and 0.0543 mM and 2.67 × 10 À 8 Ms À 1 for SV 2 W 10 , respectively, indicating a high catalytic activity and a strong affinity of POMs towards 3,3,5,5-tetramethylbenzidine (TMB). In the case of H 2 O 2 , these values were found to be 57.1 mM and 0.325 × 10 À 8 mMs À 1 for SVW 11 , and 47.7 mM and 2.72 × 10 À 8 mMs À 1 for SV 2 W 10. 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 SVW 11 and SV 2 W 10 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.
The selection of an appropriate solvent is essential for achieving high yields and selectivity in chemical reactions. The chemical and physical parameters of organic solvents have been classified into several groups, and solvents can be compared with each other with respect to these properties. The acceptor number (AN), donor number (DN) and polarity (ET N ) have been widely accepted and used for theoretically and quantitatively evaluating the properties of organic solvents. In a similar manner, the AN, DN and ET N of room temperature ionic liquids (RTILs) have been estimated from spectral changes in solvatochromic compounds. In this paper, the AN and ET N of eight types of imidazolium-based RTILs were estimated from the relationship between the AN and ET N values and the first redox potential obtained from the voltammograms of polyoxometalates (POMs) in various organic solvents. The obtained parameters were compared with those estimated by spectrophotometric methods reported previously by several groups. This new method for estimating the AN and ET N of RTILs using the voltammetric behaviour of POMs with low charge density and high symmetry could provide the other path to obtain more reliable AN and ET N of RTILs.
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