A review on the determination of veterinary drug residues in food products.

In this paper, we discuss veterinary medicine and its applications in the food industry as well as the risk to the health of humans and animals caused by these residues. We review how the veterinary residues enter and cause some detrimental effects. We also mention two techniques to determine the residue of veterinary medications that exist in food originating from animals, including classic and advanced techniques. Finally, we discuss the potential of various developed methods and compare them with some traditional techniques.

A state-of-the-art review on the nanomaterial-based sensor for detection of venlafaxine.

Venlafaxine (denoted as VFX), a member of the most extensively prescribed antidepressants, is used to handle major depressive disorder, panic disorder and anxiety. This medication affects brain chemistry, which could cause an imbalance in depressed people. VFX and its metabolites, on the other hand, are pollutants in the water environment. Through movement and transformation in several procedures like adsorption, photolysis, hydrolysis and biodegradation, they have harmed living creatures, resulting in the enhancement of diverse active chemicals found in the environment. As a result, determining VFX at modest concentrations with excellent sensitivity, specificity and repeatability are critical. To quantify VFX, various analytical methodologies have been developed. Electroanalytical processes, on the other hand, have piqued interest because of their superior benefits over traditional techniques such as speed, sensitivity, directness and affordability. Subsequently, the purpose of this article is to show how to determine VFX electrochemically using a wide range of electrodes, including CPE, GCE, MCE, SPE, PGE and ISE.

A state-of-the-art review on graphene-based nanomaterials to determine antibiotics by electrochemical techniques.

Antibiotics might build up into the human body by foodstuff metabolism, posing a serious threat to human health and safety. Establishing simple and sensitive technology for quick antibiotic evaluation is thus extremely important. Nanomaterials (or NMTs) with the advantage of possessing merits such as remarkable optical, thermal, mechanical, and electrical capabilities have been highlighted as a piece of the best promising materials for rising new paths in the creation of the future generation biosensors. This paper presents the most recent advances in the use of graphene NMTs-based biosensors to determine antibiotics. Gr-NMTs (or graphene nanomaterials) have been used in the development of a biosensor for the electrochemical signal-transducing process. The rising issues and potential chances of this field are contained to give a plan for forthcoming research orientations. As a result, this review provides a comprehensive evaluation of the nanostructured electrochemical sensing approach for antibiotic residues in various systems. In this review, various electrochemical techniques such as CV, DPV, Stripping, EIS, LSV, chronoamperometry, SWV were employed to determine antibiotics. Additionally, this also demonstrates how graphene nanomaterials are employed to detect antibiotics.

Facet-energy inspired metal oxide extended hexapods decorated with graphene quantum dots: sensitive detection of bisphenol A in live cells.

The development of crystal-facet metal oxide heterostructures has been of great interest owing to their rational design and multifunctional properties at the nanoscale level. Herein, we report a facile solution-based method for the synthesis of single-crystal Cu2O nanostructures (i.e. Cu2O-CuO) as a core. Graphene quantum dots (GQDs) with varying concentrations are fabricated on the surface of Cu2O extended hexapods (EHPs) in ethanol solution at room temperature via self-assembly, where copper acts as a sacrificial model and a stabilizer as well. The Cu2O crystals displayed a good sensing activity toward BPA oxidation owing to their high energy facets, dangling bonds and great proportion of surface copper atoms. Structural, morphological, chemical and vibrational investigations were performed in detail, presenting high crystallinity of hybrid nanocomposites and Cu2O-CuO heterojunction positions along with the growth of GQDs on the core of Cu2O-CuO crystals. The electrochemical sensing performance of the as-fabricated Cu2O-CuO@GQD EHPs was monitored for the determination of bisphenol A (BPA) as an early diagnostic marker and environmental contaminant. The synergistic effects of the boosted surface area, exposed Cu {111} crystallographic planes and mixed copper valences enhance redox reaction kinetics by increasing the electron shuttling rate at the electrode-analyte junction. Benefitting from the improved electrocatalytic activity for BPA oxidation, the electrochemical sensor displayed the lowest limit of detection (≤1 nM), good chemical stability, a broad linear range (2 nM-11 mM), and high sensitivity (636 µA mM-1 cm-2). The Cu2O-CuO@GQD EHP-based sensing platform was used for BPA detection in water and human serum samples. We have also constructed a pioneering electrochemical sensing platform for BPA detection in live cells, which might be used as a marker for early disease diagnosis.

Activities of Combined TiO2 Semiconductor Nanocatalysts Under Solar Light on the Reduction of CO2.

The materials based on TiO2 semiconductors are a promising option for electro-photocatalytic systems working as solar energy low-carbon fuels exchanger. These materials' structures are modified by doping metals and metal oxides, by metal sulfides sensitization, or by graphene supported membrane, enhancing their catalytic activity. The basic phenomenon of CO2 reduction to CH4 on Pd modified TiO2 under UV irradiation could be enhanced by Pd, or RuO2 co-doped TiO2. Sensitization with metal sulfide QDs is effective by moving of photo-excited electron from QDs to TiO2 particles. Based on characteristics of the catalysts various combinations of catalysts are proposed in order to creat catalyst systems with good CO2 reduction efficiency. From this critical review of the CO2 reduction to organic compounds by converting solar light and CO2 to storable fuels it is clear that more studies are still attractive and needed.

Facile Synthesis of r-GO@Pd/TiO2 Nanocomposites and Its Photocatalytic Activity Under Visible Light.

Reduced Graphene Oxide Wrapped Pd/TiO2 (r-GO@Pd/TiO2) which exhibited high photocatalytic activity under visible light was synthesized from commercial chemicals. The classic sol-gel method and the Ar gas bubbling composition was used in the preparation of the catalyst. Furthermore, the best Pd-doping concentration in crystals, the wrapping concentration of r-GO over nanoparticles, and the optimal calcination temperature were investigated to enhance the photocatalytic activity of the hybrid catalyst. The experimental results showed that the catalytic efficiency of r-GO@Pd/TiO2 reached maximum value at the optimum synthesis conditions: 0.7 wt% Pd-doped TiO2 by sol-gel process, calcination temperature of 550 °C, 1 mg of GO for 100 .gram wrapped Pd/TiO2. X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Transmission Electron Microscopy (TEM) techniques were conducted to determine the nanostructure of the catalysts. The average crystallite size of nanoparticles was 14 nm with perfect dispersion of Pd dots and wraps of r-GO membrane. Methyl Blue was used as an organic dye model to test the ability in wastewater treatment of the catalysts. A comparison between different catalysts' characteristics was also studied. The r-GO@Pd/TiO2 showed a higher photocatalytic activity compared to Pd/TiO2 and commercial P25. Additionally, the complete dye reduction under visible light excitation indicated that wrapping r-GO round Pd/TiO2 improved the photocatalytic activity of catalysts. The determination of the stability of r-GO@Pd/TiO2 showed that its photocatalysis was persistent over several times of recycling examination. Therefore, r-GO@ Pd/TiO2 in wastewater treatment.

Real-time tracking of hydrogen peroxide secreted by live cells using MnO2 nanoparticles intercalated layered doubled hydroxide nanohybrids.

We report a facile and green method for the fabrication of new type of electrocatalysts based on MnO2 nanoparticles incorporated on MgAl LDH P-type semiconductive channel and explore its practical applications as high-performance electrode materials for electrochemical biosensor. A series of MgAl layered doubled hydroxide (LDH) nanohybrids with fixed Mg/Al (M(2+)/M(3+) atomic ratio of 3) and varied amount of MnCl2.4H2O are fabricated by a facile co-precipitation method. This approach demonstrates the combination of distinct properties including excellent intercalation features of LDH for entrapping nanoparticles and high loading of MnO2 nanoparticles in the host layers of LDH. Among all samples, Mn5-MgAl with 0.04% loaded manganese has a good crystalline morphology. A well-dispersed MnO2 nanoparticles encapsulated into the host matrix of hydrotalcite exhibit enhanced electrocatalytic activity towards the reduction of H2O2 as well as excellent stability, selectivity and reproducibility due to synergistic effect of good catalytic ability of MnO2 and conductive MgAl LDH. Glass carbon electrode (GCE) modified with Mn5-MgAl possesses a wide linear range of 0.05-78 mM, lowest detection limit 5 µM (S/N = 3) and detection sensitivity of 0.9352 µAmM(-1). This outstanding performance enables it to be used for real-time tracking of H2O2 secreted by live HeLa cells. This work may provide new insight in clinical diagnosis, on-site environmental analysis and point of care testing devices.