MOF-based Ag NPs/CoO nanozyme for colorimetric detection of thiophanate-methyl based on analyte-enhanced sensing mechanism.

Silver nanoparticles supported on metal-organic framework (ZIF-67)-derived CoO nanostructures (Ag NPs/CoO) were synthesized via a facile in situ reduction strategy. The resulting materials exhibited pH-switchable peroxidase/catalase-like catalytic activity. Ag NP doping greatly enhanced the catalytic activity of Ag NPs/CoO towards 3,3',5,5'-tetramethylbenzidine (TMB) oxidation and HO decomposition which were 59 times (A of oxTMB) and 3 times (A of HO) higher than that of ZIF-67, respectively.

Advancing metabolic networks and mapping updated urinary metabolic fingerprints after exposure to typical carcinogenic heterocyclic aromatic amines.

Heterocyclic aromatic amines (HAAs) were not only present in cooked foods and cigarette smoke, but also measured in airborne particles and diesel-exhaust particles. Typical HAAs have been reported to induce carcinogenicity and metabolic disturbances, but how these hazardous compounds interfere with metabolic networks by regulating metabolic pathways and fingerprinting signature metabolites as biomarkers remains ambiguous. We developed an advanced strategy that adopted chemical isotope labeling ultrahigh-performance liquid chromatography coupled to quadrupole-Orbitrap high-resolution mass spectrometry for urinary nontargeted metabolomics analysis to gain new insight into in vivo physiological responses stimulated by exposure to typical HAAs.

Simple and sensitive determination of sulfites in Chinese herbal teas by ultrahigh-performance liquid chromatography tandem mass spectrometry.

Sulfites are used widely in food and beverage production to prevent browning or oxidation. However, the overingestion of sulfites is harmful to human health and may cause medical complications. Chinese herbal teas have been widely consumed for centuries.

Qualitative and Quantitative Analysis of Tumor Cell Invasion Using Au Clusters.

Tumor invasion/metastasis is still the major cause of death in cancer patients. Membrane type-1 matrix metalloproteinase (MT1-MMP) is directly related to tumor invasion/metastasis. To accurately and quickly distinguish the risk of invasion/metastasis of primary tumor cells, it is urgent to develop a simple and precise quantitative method to distinguish the expression level of MT1-MMP.

Porous chitosan/partially reduced graphene oxide/diatomite composite as an efficient adsorbent for quantitative colorimetric detection of pesticides in a complex matrix.

On-site, instrument free quantitative analysis of pesticides is of significant importance for food safety control. However, it is still a great challenge for pesticide detection in food via the current visual detection methods due to the presence of interferents in a complex matrix. In this study, a complex tea matrix had a strong effect on a gold nanoparticles (Au NPs) based colorimetric sensor for the detection of pesticides.

Chitosan-reduced graphene oxide composites with 3D structures as effective reverse dispersed solid phase extraction adsorbents for pesticides analysis.

Chitosan-reduced graphene oxide composites with 3D structures (3D CS-rGO) were prepared via a facile solvothermal synthetic strategy. The reduction of GO and crosslinking of rGO nanosheets with CS into 3D structures were achieved simultaneously in one step. The resulting 3D CS-rGO composite achieves high adsorption capacities of catechins, caffeine and pigments from tea acetonitrile extraction, especially for catechins, which is 10 times higher than that of GO (179.

Multiresidue Method for the Rapid Determination of Pesticide Residues in Tea Using Ultra Performance Liquid Chromatography Orbitrap High Resolution Mass Spectrometry and In-Syringe Dispersive Solid Phase Extraction.

A method based on in-syringe dispersive solid phase extraction (IS-D-SPE) and ultra performance liquid chromatography Orbitrap high resolution mass spectrometry for the multiresidue analysis of 117 pesticides in tea was developed. Full scan mode was acquired over an / range of 100-800 with Orbitrap resolution at 70000, followed by full scan/dd-MS mode for confirmation. The identification criteria of retention time and mass accuracy tolerance was ±0.

Facile synthesis of amine-functional reduced graphene oxides as modified quick, easy, cheap, effective, rugged and safe adsorbent for multi-pesticide residues analysis of tea.

Amine-functional reduced graphene oxide (amine-rGO) with different carbon chain length amino groups were successfully synthesized. The graphene oxides (GO) reduction as well as amino grafting were achieved simultaneously in one step via a facile solvothermal synthetic strategy. The obtained materials were characterized by X-ray diffraction, Raman spectroscopy, Fourier-transform infrared spectrometry and X-ray photoelectron spectroscopy to confirm the modification of GO with different amino groups.

Catalytic Activity Control via Crossover between Two Different Microstructures.

Metal nanocatalysts hold great promise for a wide range of heterogeneous catalytic reactions, while the optimization strategy of catalytic activity is largely restricted by particle size or shape control. Here, we demonstrate that a reversible microstructural control through the crossover between multiply twinned nanoparticle (MTP) and single crystal (SC) can be readily achieved by solvent post-treatment on gold nanoparticles (AuNPs). Polar solvents (e.

Residue pattern of polycyclic aromatic hydrocarbons during green tea manufacturing and their transfer rates during tea brewing.

Residues of polycyclic aromatic hydrocarbons (PAHs) in green tea and tea infusion were determined using gas chromatography-tandem mass spectrometry to study their dissipation pattern during green tea processing and infusion. Concentration and evaporation of PAHs during tea processing were the key factors affecting PAH residue content in product intermediates and in green tea. PAH residues in tea leaves increased by 2.

Profiling elements in Puerh tea from Yunnan province, China.

Puerh tea, as the most representative Chinese dark tea, has attracted global interest in recent years. Profiling the levels of metal elements in Puerh tea is very important since its presence is related to human health. In this study, 41 elements in 98 Puerh tea samples from Yunnan province, China including Puerh raw tea and Puerh ripe tea were evaluated by microwave digestion combined with inductively coupled plasma mass spectrometry .

Occurrence and Residue Pattern of Phthalate Esters in Fresh Tea Leaves and during Tea Manufacturing and Brewing.

The residues of 16 phthalate esters (PAEs) in fresh tea leaves and made tea were determined via gas chromatography-tandem mass spectrometry to study their distribution and degradation characteristics during tea planting and processing. Five PAEs were detected in all fresh tea leaves, and higher concentrations were detected in mature leaves. The distribution of PAEs in fresh tea leaves ranged from 69.

High Density Gold Nanoparticles Within Three-Dimensionally Mesoporous SBA-15: Adsorption Behavior and Optical Properties.

Unprecedentedly high-density (up to 79 wt%) immobilization of monodispersed gold nanoparticles (AuNPs) within mesoporous silica SBA-15 is achieved by variation of their pore size and pore-pore connectivity to enable a full access of AuNPs to the large and high-affinity internal surface of mesoporous silica (MPS) SBA-15. In addition, according to the adsorption kinetics, dipole-induced dipole interaction is suggested to be the primary driving force for adsorption of AuNPs on silica. Interestingly, the high internal surface of MPS shows much higher affinity to AuNPs than the external surface.

Solid-phase purification and extraction for the determination of trace neonicotinoid pesticides in tea infusion.

An analytical protocol that includes solid-phase purification and extraction is successfully developed for the determination of trace neonicotinoid pesticides in tea infusion. The method consists of a purification on amino-functionalized mesoporous silica SBA-15 followed by a solid-phase extraction based on graphene oxide before ultra high performance liquid chromatography with tandem mass spectrometry analysis. Parameters that significantly affected the extraction of the neonicotinoids onto graphene oxide, such as the amount of adsorbent, extraction time, pH, elution solvent, etc.

Determination of 16 phthalate esters in tea samples using a modified QuEChERS sample preparation method combined with GC-MS/MS.

A modified QuEChERS method for the determination of 16 phthalate esters (PAEs) in tea samples using GC-MS/MS was developed and validated. The kinds and amounts of adsorbents were optimised, and the crude extracts were purified using primary secondary amine (PSA), graphitised carbon black (GCB) and anhydrous magnesium sulphate (MgSO4). Compared with extraction without matrix hydration, the addition of water could achieve higher extraction efficiency.

Ordered, extra-large mesopores with highly loaded gold nanoparticles: a new sintering- and coking-resistant catalyst system.

Ordered, extra-large mesopores with highly loaded gold nanoparticles (AuNPs) exhibits unique sintering- and coking-resistant properties in gas-phase, cyclohexanol selective aerobic oxidation.

Stabilizing gold clusters by heterostructured transition-metal oxide-mesoporous silica supports for enhanced catalytic activities for CO oxidation.

A strategy for stabilizing ultrasmall gold clusters under thermal treatment has been developed. The essence of this methodology lies in construction of heterostructured transition-metal oxide-mesoporous silica supports. The supported clusters have been demonstrated to be sintering resistant and highly active for catalytic CO oxidation.

Ordered nanoporous silica with periodic 30-60 nm pores as an effective support for gold nanoparticle catalysts with enhanced lifetime.

We demonstrate that supermolecular templating allows tuning the pore size of ordered mesoporous materials in the once elusive range from 30 nm to more than 60 nm through simple control of synthetic variables (salt/supermolecule concentration and hydrothermal temperature). Gold nanoparticles (AuNPs) within the extra-large pores exhibit dramatically increased lifetime compared to those located within relatively small mesopores due to the enhanced mass diffusion that suppresses coke deposition on AuNPs.