Nanozyme-based chemical sensing is a rapidly emerging field of research. Herein, a simple colorimetric assay for the detection of hydrogen peroxide and glucose based on the peroxidase-like activity of V2O5 nanozymes has been established. In this assay, the effects of pH, substrate, nanozyme concentrations and buffer solution have been investigated. It was found that compared with 3,3′,5,5′-tetramethylbenzidine (TMB), the enzyme substrate o-phenylenediamine (OPD) seriously interfered with the H2O2 detection. Under the optimal reaction conditions, the resulting sensor displayed a good response to H2O2 with a linear range of 1 to 500 μM, and a detection limit of 1 μM at a signal-to-noise ratio of 3. A linear correlation was established between absorbance intensity and concentration of glucose from 10 to 2000 μM, with a detection limit of 10 μM. The current work presents a simple, cheap, more convenient, sensitive, and easy handling colorimetric assay.

Nanozyme-based colorimetric sensors have received considerable attention due to their unique properties. The size, shape, and surface chemistry of these nanozymes could dramatically influence their sensing behaviors. Herein, a comparative study of VO2 nanoparticles with different morphologies (nanofibers, nanosheets, and nanorods) was conducted and applied to the sensitive colorimetric detection of H2O2 and glucose. The peroxidase-like activities and mechanisms of VO2 nanoparticles were analyzed. Among the VO2 nanoparticles, VO2 nanofibers exhibited the best peroxidase-like activity. Finally, a comparative quantitative detections of H2O2 and glucose were done on fiber, sheet, and rod nanoparticles. Under the optimal reaction conditions, the lower limit of detection (LOD) of the VO2 nanofibers, nanosheets, and nanorods for H2O2 are found to be 0.018, 0.266, and 0.41 mM, respectively. The VO2 nanofibers, nanosheets, and nanorods show the linear response for H2O2 from 0.025–10, 0.488–62.5, and 0.488–15.625 mM, respectively. The lower limit of detection (LOD) of the VO2 nanofibers, nanosheets, and nanorods for glucose are found to be 0.009, 0.348, and 0.437 mM, respectively. The VO2 nanofibers, nanosheets, and nanorods show the linear response for glucose from 0.01–10, 0.625–15, and 0.625–10 mM, respectively. The proposed work will contribute to the nanozyme-based colorimetric assay.

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Polyoxometalates (POMs) are inorganic clusters that possess potential anti-bacterial, anti-viral, and anti-tumor activities. Herein, the in vitro anti-proliferation activities of K12[V18O42(H2O)]∙6H2O (V18) have been investigated on the MCF-7 and MDA-MB-231 cell lines. The results indicated that V18 could inhibit the proliferation of MCF-7 (IC50, 11.95 μM at 48 h) in a dose-dependent manner compared to the positive control, 5-fluorouracil (5-Fu, p < 0.05). The anti-proliferation activity of V18 might be mediated by arrest of the MCF-7 cells in the G2/M phase and induction of apoptosis and necrosis. Moreover, V18 can effectively quench the fluorescence of ctDNA. The binding mode between them may be groove or outside stacking binding. V18 can also effectively quench the intrinsic fluorescence of bovine serum albumin (BSA) and human serum albumin (HSA) via static quenching, and changed the conformation of BSA and HSA.

Fungal infections pose a serious threat to human health. Polyoxometalates (POMs) are metal–oxygen clusters with potential application in the control of microbial infections. Herein, the Ag3PW12O40 composites have been synthesized and verified by Fourier transform infrared (FT-IR) spectrum, transmission electron microscopy (TEM), scanning electron microscope (SEM), elemental analysis, and X-ray diffraction (XRD). The antifungal activities of Ag3PW12O40 were screened in 19 Candida species strains through the determination of minimum inhibitory concentration (MIC) by the microdilution checkerboard technique. The minimum inhibitory concentration (MIC50) values of Ag3PW12O40 are 2~32 μg/mL to the Candida species. The MIC80 value of Ag3PW12O40 to resistant clinical isolates C. albicans HL963 is 8 μg/mL, which is lower than the positive control, fluconazole (FLC). The mechanism against C. albicans HL963 results show that Ag3PW12O40 can decrease the ergosterol content. The expressions of ERG1, ERG7, and ERG11, which impact on the synthesis of ergosterol, are all prominently upregulated by Ag3PW12O40. It indicates that Ag3PW12O40 is a candidate in the development of new antifungal agents.

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The rise in the number of fungal infections is requiring the rapid development of novel antifungal agents. A new polyoxovanadate functionalized by Zn-fluconazole coordination complexes, Zn3(FLC)6V10O28·10H2O (ZnFLC) (FLC = fluconazole) has been synthesized and evaluated for in vitro antifungal against Candida species. The identity of ZnFLC were confirmed by elemental analysis, IR spectrum, and single-crystal X-ray diffraction. The antifungal activities of ZnFLC was screened in 19 Candida species strains using the microdilution checkerboard technique. The minimum inhibitory concentration (MIC80) value of ZnFLC is 4 μg/mL on the azole-resistant clinical isolates of C. albicans HL973, which is lower than the positive control, FLC. The mechanism of ZnFLC against C. albicans HL973 showed that ZnFLC damaged the fungal cell membrane and reduced the ergosterol content. The expression of ERG1, ERG7, ERG11 ERG27, and ERG28, which have effects on the synthesis of ergosterol, were all significantly upregulated by ZnFLC.