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Heterogeneous Fenton-like magnetic nanosphere coated with VO x quantum dots for enhanced hydroxyl radicals decolorization. Electrostatic adsorption realizes the close-range action mechanism. The conventional Fenton reaction has played a vital role in the degradation of pollutants. However, this reaction is prone to forming iron mud, which causes secondary pollution. Additionally, most of the Fenton systems are in homogeneous forms and suffer from intrinsically short lifetimes, hydroxyl radicals that have short diffusion distances (OH) and non-recyclability. Herein, using magnetic composites (Fe 3 O 4 @SiO 2) as the carrier and vanadium oxide quantum dots (VO x QDs) as the catalyst, we developed a renewable, heterogeneous, magnetic Fenton-like system for dye degradation in polluted wastewater. The VO x QDs of less than 10 nm showed large specific surface areas, enhanced surface-exposed active atoms, and low toxicity, which are favourable for developing an efficient Fenton-like system. In addition, owing to the electrostatic adsorption between the as-prepared catalyst and the dye molecules, the distance for OH sterilization and decolorization can be significantly reduced, overcoming the shortcomings of the short oxidation distance of OH. Accordingly, the degradation of dyes can be achieved in five seconds. Furthermore, the catalysts can be effectively separated and recycled based on their magnetic features, while the secondary pollution from both the catalysts and the incompletely degraded dye molecules into the environment can be avoided. In addition, the Fe 3 O 4 @SiO 2 is able to maintain a superior morphology, and the composite material (VO x QDs/Fe 3 O 4 @SiO 2) maintains more than 90% of the degradation effects even after eight repeated tests. [ABSTRACT FROM AUTHOR]

Abstract: Vanadium oxide (VOx) nanomaterials have been attracting great attention recently due to their outstanding physicochemical properties. Engineering VOx into quantum dots (QDs) should bring new properties and potential for applications, but has not been reported until now. Meanwhile, the shortcomings in QDs synthesis such as needing high temperature and expensive instruments still need to be overcome. Herein, VOxQDs were generated via a simple ultrasonic and agitation strategy at room temperature using DMSO as both solvent and exfoliation agent. The VOx QDs exhibited blue fluorescence under 365 nm ultraviolet irradiation. They were with good monodispersion, narrow size distribution and average particle size of 3.3±0.3 nm. The VOxQDs can be used as a competitive fluorescent sensing probe for label‐free specific detection of Fe3+ and PPi based on the ON‐OFF or ON‐OFF‐ON fluorescent principle, respectively. Moreover, the antibacterial activity of the as‐prepared VOxQDs was found, which could damage the cell membrane and inhibit the bacterial growth of both Gram (+) (Staphylococcus aureus) and Gram (−) (Escherichia coli) bacteria, respectively. [ABSTRACT FROM AUTHOR]

Silver nanoparticles with vanadium oxide nanowires were obtained using the vanadium oxide quantum dots as both reductants and stabilizers. It was loaded into electrospun dressing for efficient bacteria-infected wound healing as confirmed by both in vitro and in vivo tests. [Display omitted] Silver nanoparticles (AgNPs) have been widely recognised as effective antibacterial materials in textiles for enhancing wound healing. However, high loadings of AgNPs are toxic and expensive. Thus, it is ideal to prepare AgNPs in a favourable nanostructure for stable and effective conjugation with the textile carrier by selecting a reductant and stabiliser that contributes to the antibacterial effect. Here, silver nanoparticles/vanadium oxide nanowires (Ag/VO x NWs) were prepared via a one-step reduction strategy using vanadium oxide quantum dots (VO x QDs) as both the reductant and stabiliser. VO x QDs possess antibacterial properties, which aid in minimising the applied silver content while enhancing bactericidal performance. Silver can self-aggregate into nanoparticles as well as promote the formation of vanadium oxide nanowires (VO x NWs). Accordingly, the Ag/VO x NWs exhibited remarkable antibacterial effects against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus). The nanowire structure of the Ag/VO x NWs was favourable for effective loading into a sodium alginate (SA) gel fabric to form a wound dressing. The effective loading of Ag/VO x NWs on SA was conducive to the complete dispersion of the bacteriostatic agent and enhanced the antibacterial activity of AgNPs. The wound dressing efficiently suppressed the growth of wound bacteria and promoted wound healing in vivo. [ABSTRACT FROM AUTHOR]

Vanadium oxide nanodots (VO x NDs) with bienzymatic synergism were constructed and applied to wound healing in vivo with their highly efficiently antibacterial properties. Antibiotic resistance is a common phenomenon observed during treatment with antibacterials. Use of nanozymes, especially those with synergistic enzyme-like activities, as antibacterials could overcome this problem, but their synthesis is limited by their high cost and/or complex production process. Herein, vanadium oxide nanodots (VO x NDs) were prepared via a one-step bottom-up ethanol-thermal method using vanadium trichloride as the precursor. VO x NDs alone possess bienzyme mimics of peroxidase and oxidase. Accordingly, highly efficient antibacterials against drug-resistant bacteria can be obtained through synergistic catalysis; the oxidase-like activity decomposes O 2 to generate superoxide anion radical (O 2 −) and hydroxyl radicals (OH), and the intrinsic peroxidase-like activity can further induce the production of OH from external H 2 O 2. Consequently, H 2 O 2 concentration could decrease up to four magnitude orders with VO x NDs to achieve an antibacterial efficacy similar to that of H 2 O 2 alone. Wound healing in vivo further confirms the high antibacterial efficiency, good biocompatibility, and application potential of the synergistic antibacterial system due to the "nano" structure of VO x NDs. The method of synthesis of nanodot antibacterials described in this paper is inexpensive, and the results of this study reveal the multi-enzymatic synergism of nanozymes. [ABSTRACT FROM AUTHOR]

The vanadium oxide quantum dots (VO x QDs) based sensitive fluorescent sensing method was designed and successfully applied for detection of MoO 4 2− anions in river and man-made lake samples. [Display omitted] • The VO x QDs can be used as a competitive fluorescent sensing probe. • Facile and sensitive fluorescent sensor based on VO x QDs was designed. • The as-proposed assay can efficiently avoid the interference of almost all the anions and cations commonly existing in the environment. • The VO x QDs-based fluorescent sensing method can be used in sensitive molybdenum acid anions (MoO 4 2−) assays in river and lake water samples. The detection of molybdate (MoO 4 2−) is of great significance in environmental area since the high concentration will cause poison to animals, plants and human body. Fluorescent assays were considered as a promising analytical strategy due to its high sensitivity, wide linear range and so on, but were rarely reported because of the lack of selective probes. Considering the electron transfer between MoO 4 2− and vanadium, vanadium oxide quantum dots (VO x QDs) were designed as fluorescent probes for selective and sensitive detection of MoO 4 2− in aqueous samples. Such VO x QDs exhibit uniform dispersion, narrow size distribution and about average diameter of 3.09 ± 0.14 nm. Under the optimized conditions, the relationship between fluorescence (FL) intensity and MoO 4 2− anion concentrations were linear in the range of 2–300 µM (R2 = 0.990) and 400–800 µM (R2 = 0.988) while the lowest limit of detection was 1.5 µM MoO 4 2−. Especially, the as-proposed assay can efficiently avoid the interference of almost all the anions and cations commonly existing in the environment. More importantly, the VO x QDs-based fluorescent sensing method was successfully applied to the assays of MoO 4 2− in river and lake water samples. [ABSTRACT FROM AUTHOR]

• Vanadium oxide quantum dots (VO x QDs) were optimized to reach good monodisperblity and uniform size distribution. • The as-prepared VO x QDs exhibited more effective peroxidase-like activity. • Facile and sensitive colorimetric sensor based on VO x QDs was designed. • The sensor can be used in sensitive glucose assays in serum. The environmental vulnerability of the natural enzyme have always been the most concerned issue in the diagnosis of blood glucose levels, which could be settled by the discovery and application of nanozyme mimics. However, the nanozyme still encountered with the problem of complex preparation process or low enzymatic activities. Herein, peroxidase-like vanadium oxide quantum dots (VO x QDs) were synthesized via a one-step bottom-up solvothermal method using vanadium (Ⅲ) trichloride (VCl 3) powder as the precursor. Besides, the most favorable temperature and solvent for VO x QDs synthesis were confirmed. Due to the inherent properties of quantum dots, including larger specific surface areas and more active sites, the as-prepared VO x QDs exhibited 43 times lower value of K m and 32 times higher one of V max than those of natural peroxidase using H 2 O 2 as the substrate, indicating the higher affinity and stronger peroxidase-like activity of the VO x QDs nanozymes. Accordingly, a facile and sensitive colorimetric sensor to detect glucose was designed via the integrated enzyme system of VO x QDs and glucose oxidase, which showed wider linear range of 0.005 - 2 mM glucose and lower limit of detection of 1.7 μM compared with those of many other peroxidase-like nanozymes. Especially, the colorimetric sensor was demonstrated with reliable and satisfactory performance in detection of glucose in human serum, which was in good accordance with the clinical results provided from the domestic hospital. Peroxidase-like vanadium oxide quantum dots (VO x QDs) based facile and sensitive colorimetric sensor was designed and successfully applied for detection of glucose in human serum. Image, graphical abstract [ABSTRACT FROM AUTHOR]