Preliminary Study On Vanadium Oxide Quantum Dot Nanoenzymes And Antibacterial Materials

Nanozymes are catalytic nanomaterials with enzyme-like characteristics.Obvious advantages,such as low cost,high tolerance to harsh environment,easy to expand production,can be modified or functionalized,precisely the characteristics that natural enzymes lack.Many nanomaterials,such as precious metals,metal oxides,metal sulfides,carbon-based materials,have been found to mimic a variety of enzymes.At present,nanozymes have been widely used in biomolecular detection,cell protection,cancer treatment,antimicrobial and environmental protection,and so on,showed great development prospects.Among them,the application of nanozymes in the field of bacteriostasis is an important aspect,because nanozymes have good ability to regulate free radicals,which can produce excessive free radicals in the environment and play a bactericidal role.However,there are still some shortcomings in nanozymes,such as single catalytic site,low catalytic efficiency or complex synthesis methods,etc.Therefore,it is urgent to develop new nanomaterials as low-cost,high-performance nanozymes.Transition metal oxide quantum dots?TMQDs?are a class of nanomaterials with three-dimensional size less than 100 nm?generally less than 10 nm?,which have various advantages,such as large surface area,more surface active sites,good dispersion,low toxicity and good biocompatibility,etc.Most importantly,TMQDs based nanozymes are much better than general nanozymes in catalytic activity and enzyme activities'diversity.Therefore,it is a significant attempt to develop novel TMQDs nanozymes and apply them to the field of bacteriostasis.In this paper,vanadium oxide quantum dots?VOxQDs?were synthesized by two methods for the first time:one-step ethanol thermal method and room temperature ultrasonic stirring method.The synthesized VOxQDs have been applied in the fields of nanozymes and bacteriostasis.In order to enhance the bacteriostasis,silver/vanadium oxide nanowires?Ag/VOx NW?were synthesized by one-step reduction of silver nitrate with VOxQDs.The bacteriostasis of the nanowires is much stronger than that of VOxQDs.The wound antimicrobial dressing with high efficiency can be made by spinning with Ag/VOx NW.1.VOx QDs were synthesized herein via a one-pot top-down ethanol-thermal method using bulk VO2 as the prescusor.The VOxQDs showed not only oxidase-and peroxidase-like activities in ethanol as the main background solution,but also exhibited additional superoxide oxidase mimetic activity in phosphate buffer solution.Furthermore,the TMB-VOxQDs system in the ethanol-BGS produced three distinct colors in the presence of hydrogen peroxide?H2O2?at three different concentration gradients?10-90?M,0.1-10 mM and 20-100 mM?.Accordingly,we constructed a three-dimensional?3D?coordinate system?3D-CS?by using the three variables:the initial velocities,the maximum absorption values and the visual colors of the enzymatic reaction system.As a result,the rapid detection of H2O2 can be achieved while effectively avoiding the faked appearance due to the inhibition effects to the enzymatic system at too high H2O2concentration.The applicability of the VOxQDs based 3D-CS was further verified via the facile and accurate H2O2 assays in three different practical samples.2.VOxQDs were generated via a simple ultrasonic and agitation strategy at room temperature using DMSO as both solvent and exfoliation agent.Based on the characterization of ultraviolet-visible?fluorescence?Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy,etc.,VOxQDs were found good monodispersity,narrow particle size distribution?the diameter and thickness of the VOxQDs were 3.32 and 3.28 nm,respectively?and good crystallinity.The VOxQDs were 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 discovered,which could induce the damage of cell membrane and inhibit the bacterial growth of both Gram?+??Staphylococcus aureus?and Gram?-??Escherichia coli?bacteria,respectively.3.To explore more potential applications of VOxQDs,the Ag/VOx NW were obtained by one-step reduction of VOxQDs at room temperature and spinned into biocompatible sodium alginate for the construction of a new wound dressing,which can obviously inhibit the growth of wound bacteria and promote wound healing in rats.In a word,new VOxQDs were developed and their multi-enzyme mimetic activity and bacteriostasis were confirmed.The multi-enzyme activities were used in the design of 3D sensors,which enlarges the detection range of biomolecules.Antibacterial properties of VOxQDs applied to the development of antibacterial dressing,which showed broad prospects in clinical application.