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Regulatory authorities are expected to measure concentration of contaminants in foodstuffs, but the simple determination of total amount cannot be sufficient for fully judging its impact on the human health. In particular, the methylation of metals generally increases their toxicity; therefore validated analytical methods producing reliable results for the assessment of methylated species are highly...
In this work we have grown particular zinc oxide two-dimensional nanostructures which are essentially a series of hexagonal very thin sheets. The hexagonal wurtzite crystal structure gives them their peculiar shape, whose dimensions are few microns wide, with a thickness in the order of 25nm. Such kind of nanostructure, grown by thermal oxidation of evaporated metallic zinc on a silica substrate,...
The electrochemical behavior of ondansetron was studied on the multi-walled carbon nanotubes/Nafion polymer composite modified glassy carbon electrode (MWCNTs–Nafion/GCE). The oxidation peak potential was shifted from 1.32V to 1.18V compared to the bare electrode indicating excellent electrocatalytic activity of immobilized film toward drug molecule. The modified electrode exhibited a remarkable enhancement...
The potential of multispectral imaging of autofluorescence to map sensory flavour properties and fluorophore concentrations in cod caviar paste has been investigated. Cod caviar paste was used as a case product and it was stored over time, under different headspace gas composition and light exposure conditions, to obtain a relevant span in lipid oxidation and sensory properties. Samples were divided...
The manipulation of the surface chemistry of semiconductor nanocrystals has been exploited to implement distinct sensing strategies in many analytical applications. In this work, reduced glutathione (GSH) was added at reaction time, as an electron-donor ligand, to markedly increase the quantum yield and the emission efficiency of MPA-capped CdTe quantum dots. The developed approach was employed in...
In this study, dendrimer grafted graphene oxide nanosheets (dGO) were prepared by covalent reaction. The successful synthesis of dGO was confirmed by Fourier-transform infrared spectra, Raman spectra, Thermo gravimetric analysis and Zeta potential. Taking advantages of large surface area, excellent biocompatibility and abundant functional groups, dGO provided an ideal substrate for trypsin immobilization...
DNA sequences with guanine repeats can be induced to form G-quartets that adopt G-quadruplex structures in the presence of thioflavin T (ThT). ThT plays a dual role of inducing DNA sequences to fold into quadruplex structures and of sensing the change by its remarkable fluorescence enhancement. ThT binding to the DNA sequences with guanine repeats showed highly specific fluorescence enhancement compared...
Graphene oxide (GO)–thionine (TH) nanocomposite was prepared by π–π stacking. The nanocomposite was cast-coated on a glassy carbon electrode (GCE) to prepare an electroreduced GO (ERGO)–TH/GCE, then 2-mercaptoethanesulfonate (MES) was covalently tethered to ERGO–TH by potentiostatic anodization to form an ERGO–TH–MES/GCE. The thiolation reaction was monitored by electrochemical quartz crystal microbalance...
To prevent the degradation of the device characteristics it is important to detect the organic contaminants adsorbed on the wafers. In this respect, a reliable qualitative and quantitative analytical method for analysis of semi-volatile organic compounds which can adsorb on wafer surfaces is of paramount importance.Here, we present a new analytical method based on Wafer Outgassing System (WOS) coupled...
Tetracycline and Eu 3+ , while coexisting, usually appear as a complex by chelating. This complex shows low fluorescence intensity, leading to its limitation of analytical goals. Gold nanoclusters (AuNCs), emerging as novel nano-material, are attracting increasing attentions in multiple fields. Herein, gold nanoclusters first function as a fluorescence-enhanced reagent rather than a conventional...
A novel intrinsic fluorescence method for the direct determination of l-phenylalanine, l-tyrosine, and l-tryptophan in human plasma is presented. By using fluorescence excitation–emission–pH–sample data array in combination with four-way calibration method based on the quadrilinear component model, the proposed approach successfully achieved quantitative analysis of the aromatic amino acids in human...
During the enzymatic reaction of the heme-protein Horseradish peroxidase (HRP) with hydrogen peroxide there are changes in the molecular absorption spectra of HRP and its different oxidation states which can be used for quantitative determination of the substrate. One of these intermediate oxidation states is the HRPII, with iron as an oxyferryl. This compound is assumed to be responsible for the...
The hybrid nanocomposite that consists of multiwalled carbon nanotubes (MWCNTs) and magnetite (Fe 3 O 4 ) was fabricated by chemical co-precipitation method. Briefly, CNTs were oxidized with acids to form carboxylic group and then co-precipitated with Fe 3 O 4 to form CNT–Fe 3 O 4 nanocomposites. The nanocomposites were characterized by SEM, HRTEM, XRD,...
Although Zn 2+ ions are involved in large numbers of physiopathological processes, non-invasive detection of Zn 2+ ions in opaque biological samples remains a huge challenge. Here, we developed a novel zinc-responsive hyperpolarized (HP) 129 Xe-based NMR molecular sensor. This HP 129 Xe-based NMR molecular sensor was synthesized by attaching 2-(diphenylphosphino) benzenamine...
In this work, the suitability of bulk polyethersulfone (PES) for sorptive microextraction of eight polar, chlorinated phenoxy acids and dicamba from environmental water samples is assessed and the analytical features of the optimized method are compared to those reported for other microextraction techniques. Under optimized conditions, extractions were performed with samples (18mL) adjusted at pH...
A new method for the isolation and analysis of cholesterol oxidation products (COPs) using solid phase extraction (SPE) and silica columns was developed using gas chromatography-flame ion detection (GC-FID). The method comprises of saponification and liquid–liquid extraction of the unsaponifiable fraction prior to the isolation and derivatization of the COPs to trimethylsilyl ethers. The COPs used...
This work observed the anodic electrochemiluminescence (ECL) of C 3 N 4 nanosheets (CNNS) for the first time. The ECL emission was 40 times stronger than that from bulk g-C 3 N 4 in the presence of triethylamine (Et 3 N) as a coreactant due to large surface-to-volume ratio, which enhanced the sensitivity for biosensing. At pH 7.0, the CNNS modified electrode...
The sensitivity of surface plasmon resonance (SPR) biosensor technology for detection of bacterial analytes is investigated as a function of (a) sample flow conditions and (b) depth of probing electromagnetic field. These parameters are extremely important as such analytes exhibit large (of around micrometer) size which significantly hinders their diffusion-driven transfer from a liquid sample to...
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