Rong Wang

Layered vanadium(IV) disulfide nanosheets as a peroxidase-like nanozyme for colorimetric detection of glucose

AbstractThe authors have discovered that vanadium disulfide (VS2) nanosheets, synthesized by a hydrothermal method, exert stable peroxidase-like activity. The catalytic activity, with H2O2 as a cosubstrate, follows Michaelis-Menten kinetics and varies with temperature, pH value and H2O2 concentration. Two-dimensional VS2 sheets acting as peroxidase (POx) mimics can replace horseradish peroxidase due to their availability, robustness, and reusability. The POx-like activity of VS2 sheets was exploited to design a colorimetric glucose assay by using 3,3′,5,5′-tetramethylbenzidine as a substrate and by working at an analytical wavelength of 652xa0nm. The assay covers the 5 to 250xa0μM glucose concentration range with a 1.5xa0μM detection limit. It was applied to the analysis of glucose in fruit juice. In our perception, the peroxidase-like nanozyme out of the family of transition metal dichalcogenides presented here has a wide scope in that it may stimulate promising biocatalytic applications in biotechnology and analytical chemistry.n Graphical abstractLayered VS2 nanosheets were prepared via hydrothermal synthesis and are shown to exert superior peroxidase-mimicking activity. Using these POx nano-mimics, a sensitive colorimetric assay for glucose was developed and applied to fruit juice analysis. This work unlocks the access of VS2 to biocatalysis and bioassays.

In-Situ Fixation of All-Inorganic Mo–Fe–S Clusters for the Highly Selective Removal of Lead(II)

The selective adsorption by suitable substrate materials is considered one of the most economical methods. In this work, an all-inorganic bimetallic Mo-Fe-S cluster is facilely achieved through in situ chemical fixation of tetrathiomolybdate (TTM) on Fe3O4 nanoparticles (NPs) at room temperature (donated as FeMoS NPs). The bimetallic building blocks on the obtained FeMoS NPs possess a monovacancy species of sulfur, endowing FeMoS NPs with a selectivity order of Zn2+, Mn2+, Ni2+ < Cd2+ ≪ Cu2+ < Pb2+ for metal-ion adsorption, a novel application for the Mo-Fe-S clusters. Particularly, with the highest selectivity for Pb2+ (Kd ≈ 107), which is about 3 × 103-1 × 106 times higher than those for other ions and has exceeded that of a series of outstanding sorbents reported for Pb2+, FeMoS NPs can efficiently reduce the concentration of Pb2+ from ∼10 ppm to an extremely low level of ∼1 ppb. This facile and rational fabrication of the Mo-Fe-S cluster with Fe3O4 represents a feasible approach to cheaply develop novel and efficient materials for the selective removal of lead(II).

A hybrid monolithic column based on layered double hydroxide-alginate hydrogel for selective solid phase extraction of lead ions in food and water samples

In order to develop an accurate and precise determination method based on solid phase extraction of Pb(II) in food and water samples, a hybrid monolithic column based on layered double hydroxides (LDHs) nanosheets-alginate hydrogel has been synthesized. Combining the advantages of porous 3D framework of hydrogel with selective adsorption of LDHs toward Pb(II), the hydrogel-based hybrid monolithic column shows enhanced enrichment selectivity and efficiency for target ions. Effects of hydrogel composition, pH, concentration and type of eluent, sample volume, and interfering ions on the recoveries of the analytes were also investigated. Under the optimal experiment conditions of method, the limit of detection, preconcentration factor and precision as RSD% are found to be 0.39u202fμgu202fL-1, 53.7 and 2.65%, respectively. Trace Pb(II) can be quantitatively preconcentrated at pH 6.0 with recoveries >97%. Finally, the method was successfully verified by analyzing spiked Pb2+ in water and drinking samples.

Antibiotic-loaded MoS2 nanosheets to combat bacterial resistance via biofilm inhibition

The emergence of antibiotic resistance has resulted in increasing difficulty in treating clinical infections associated with biofilm formation, one of the key processes in turn contributing to enhanced antibiotic resistance. With the rapid development of nanotechnology, a new way to overcome antibiotic resistance has opened up. Based on the many and diverse properties of MoS2 nanosheets that have attracted wide attention, in particular their antibacterial potential, herein, a novel antimicrobial agent to combat resistant gram-positive Staphylococcus aureus and gram-negative Salmonella was prepared using chitosan functionalized MoS2 nanosheets loading tetracycline hydrochloride drugs (abbreviated to CM-TH). The antibacterial and anti-biofilm activities of the CM-TH nanocomposites showed the synergetic effect that the combination of nanomaterials and antibiotics was more efficient than either working alone. In particularly, the minimum inhibitory concentration values generally decreased by a factor of dozens, suggesting that CM-TH may become a possible alternative to traditional antibiotics in disrupting biofilms and overcoming antibiotic resistance in treating medical diseases.The emergence of antibiotic resistance has resulted in an increasing difficulty treating clinical infections associated with biofilms formation, one of the key processes contributed to enhance antibiotic resistance in return. With the rapid development of nanotechnology, a new way to overcome antibiotic resistance was opened up. Based on multiple properties especially antibacterial potential of MoS2 nanosheets that have aroused wide attention, herein, a novel antimicrobial agent to combat resistant gram-positive Staphylococcus aureus (S. aureus) and gram-negative Salmonella was prepared using chitosan functionalized MoS2 nanosheets loading tetracycline hydrochloride drugs (abbreviated to CM-TH). The antibacterial and anti-biofilm activities of CM-TH nanocomposites expressed a synergy effect that the combination of nanomaterials and antibiotics were more efficient than both alone did. Particularly, the MIC values were generally decreased by a factor of dozens, suggesting CM-TH may become a possible alternative to traditional antibiotics in disrupting the biofilms and further to overcome antibiotic resistance in treating medical diseases.

Highly sensitive furazolidone monitoring in milk by a signal amplified lateral flow assay based on magnetite nanoparticles labeled dual-probe

We presented a signal amplified lateral flow assay (LFA) based on magnetite nanoparticles (MNPs) labeled dual-probe and applied it in the high sensitive and rapid on-site detection of furazolidone metabolite of 3-amino-2-oxazolidinone (AOZ). The amplified signal benefited from high affinity between two probes of MNPs labeled murine monoclonal antibody (MNPs-MAb) and goat anti-mouse antibody (MNPs-GAMA) and was achieved by the generation of dual-probe network complex. This developed method could realize high sensitive detection of AOZ with a threshold value of 0.88u202fngu202fmL-1 and a detection limit of 0.044u202fngu202fmL-1, the sensitivity was at least 10-fold improved than that of the traditional gold nanoparticle based LFA. This facile developed assay was successfully applied for rapid detection of AOZ in milk samples. The proposed method paves a new way for on-site screening of other hazardous substances in food and can be referred in all lateral flow assays.

Patulin removal from apple juice using a novel cysteine-functionalized metal-organic framework adsorbent

Patulin (PAT) is one of the most common toxic contaminants of apple juice, which causes severe food safety issues throughout the apple industry. In order to remove PAT efficiently, a metal-organic framework-based adsorbent (UiO-66(NH2)@Au-Cys) was successfully synthesized and used for PAT removal from juice-pH simulation solution and real apple juice. Batch adsorption experiments were systematically performed to study the adsorption behavior for PAT. The results showed that adsorption process could be well described by the Pseudo-second order model and Freundlich isotherm model. The maximum adsorption capacity (4.38u202fµg/mg) was 10 times higher than the microbe-based biosorbents. Thermodynamic investigation demonstrated that adsorption process was spontaneous and endothermic. Furthermore, no marked cytotoxicity on NIH 3T3 cell lines was observed when the concentration of the adsorbent was lower than 10u202fμg/mL. Therefore, UiO-66(NH2)@Au-Cys is a potential adsorbent for PAT removal from apple juice with little quality changes.

Monolithic copper selenide submicron particulate film/copper foam anode catalyst for ultrasensitive electrochemical glucose sensing in human blood serum

Herein, we introduce our recent finding that a copper selenide submicron particulate film supported on an underlying Cu foam (Cu2Se SPs/CF) via an in situ facile chemical vapor deposition process could be well utilized for glucose sensing. This monolithic electrode shows excellent catalytic activity toward glucose with an ultrahigh sensitivity (18u2009660 μA mM-1 cm-2), a low determination limit (LOD) of 0.25 μM, a fast response time of 3 s and good selectivity, which is much superior to almost all reported Cu-based sensors. It also shows good reproducibility and feasibility in glucose detection in diluted human serum samples. This good performance could be attributed to the overall good catalytic activity of both the Cu2Se phase and Cu foam, the high surface area provided by the unique submicron particulate-formed Cu2Se film, and good conductivity of the integral Cu2Se SPs/CF.