ESIPT-capable Eu3+-metallopolymer with colour-tunable emission for selective visual sensing of Zn2+ ion

The copolymerization between 4-VP-PHI, MMA and the Eu3+-complex results in white light emitting Eu3+-metallopolymer, which not only has a lower detection limit, but also a more remarkable color change compared to 4-VP-PHI for the sensing of Zn2+.

Electrochemical biosensor based on CuPt alloy NTs-AOE for the ultrasensitive detection of organophosphate pesticides

The electrode material is vital for the performance of the electrochemical biosensor. Lately, many nanomaterials have been developed to improve the sensitivity and detection efficiency of the biosensors. In this work, a kind of one-dimensional nanomaterials, the CuPt alloy nanotubes with an open end (CuPt alloy NTs-AOE), was explored. The nanotubes with an open end can provide a larger electrochemical active surface area and more active sites for the immobilization of enzyme. The CuPt alloy displays excellent conductivity and catalytic activity. In addition, the Cu shows the great affinity to thio-compounds, which can greatly enhance the detection efficiency and sensitivity. As a result, the prepared biosensor demonstrates the wider linear range of 9.98×10-10 - 9.98×10-5 g/L for fenitrothion and 9.94×10-11 - 9.94×10-4 g/L for dichlorvos (as model OPs ) and with the lower detection limit of 1.84 ×10-10 g/L and 6.31×10-12 g/L (S/N = 3), respectively. Besides, the biosensor has been used to detect the real samples and obtains satisfactory recoveries (95.58 % - 100.56 %).

Ppb-Level Butanone Sensor Based on ZnO-TiO2-rGO Nanocomposites

In this paper, ZnO-TiO2-rGO nanocomposites were successfully synthesized by the hydrothermal method. The morphology and structure of the synthesized nanomaterials were characterized by SEM, XRD, HRTEM, and XPS. Butanone is a typical ketone product. The vapors are extremely harmful once exposed, triggering skin irritation in mild cases and affecting our breathing in severe cases. In this paper, the gas-sensing properties of TiO2, ZnO, ZnO-TiO2, and ZnO-TiO2-rGO nanomaterials to butanone vapor were studied. The optimum operating temperature of the ZnO-TiO2-rGO sensor is 145 °C, which is substantially lower than the other three sensors. The selectivity for butanone vapor is greatly improved, and the response is 5.6 times higher than that of other organic gases. The lower detection limit to butanone can reach 63 ppb. Therefore, the ZnO-TiO2-rGO sensor demonstrates excellent gas-sensing performance to butanone. Meanwhile, the gas-sensing mechanism of the ZnO-TiO2-rGO sensor to butanone vapor was also analyzed.

Schiff Base Functionalized 1,2,4-Triazole and Pyrene Derivatives for Selective and Sensitive Detection of Cu2+ in the Mixed Organic- Aqueous Media

We have prepared Schiff base functionalized 1,2,4-Triazole and Pyrene derivatives for selective, sensitive, and naked eye colorimetric detection of Cu2+ in the mixed organic- aqueous media. Amongst the 18 different metal ions studied for absorption and fluorescence titration, only Cu2+ ion encourages the modification in spectral properties of Schiff base functionalized 1,2,4-Triazole and Pyrene Probe. The stoichiometric ratio of the Probe-Cu2+ complex was determined to be 2:1 according to Job’s plot. The lower detection limit estimated for Cu2+ is 0.234 nM which shows excellent sensitivity and selectivity of the present analytical method towards detection of Cu2+ ion in the mixed organic-aqueous media. The present approach has been successfully utilized for the quantitative determination of Cu2+ ion from environmental aqueous solution.

Glucose Biosensor Based on Glucose Oxidase-Horseradish Peroxidase/Multiporous Tin Oxide (SnO2) Modified Electrode

The fabrication of a network of glucose oxidase-horseradish peroxidase/tin oxide (GOx-HRP/SnO2), immobilized onto a glassy carbon electrode (GCE) and its utilization as a biosensor for glucose detection is reported. The network established with GOx-HRP/SnO2 possess high sensitivity and stability by performing the electrocatalytic features in the sensing of glucose. The turbidity of fabrication had been scanned and analyzed using UV-vis spectroscopy. The morphology and composition of the fabricated GOx-HRP/SnO2 networks were characterized by scanning electron microscopy (SEM). Cyclic voltammetry and amperometry were employed to study the electrochemical properties of the proposed biosensor. The effect of applied electrode potential and pH were systemically investigated. The biosensor responds to glucose at work potential values between −400 mV, and exhibited a lower detection limit (0.025 mM) and long linear range (0.25 to 7.0 mM), and was resistant to common interferences.

A Sensitive Plasma Insulin Immunoassay to Establish the Diagnosis of Congenital Hyperinsulinism

BackgroundThe diagnosis of congenital hyperinsulinism (CHI) may be hampered by a plasma (p-) insulin detection limit of 12–18 pmol/L (2–3 mU/L).ObjectiveTo evaluate the diagnostic performance of a sensitive insulin immunoassay and to find the optimal p-insulin cut-off for the diagnosis of CHI.MethodsDiagnostic fasting tests, performed without medication or i.v.-glucose, were investigated in children with a clinical diagnosis of CHI, or idiopathic ketotic hypoglycemia (IKH). The CHI diagnosis was either clinical or by the alternative, p-insulin-free criteria; hypoglycemia plus disease-causing genetic mutations and/or CHI-compatible pancreatic histopathology. We included diagnostic p-insulin samples with simultaneous p-glucose <3.2 mmol/L and used a sensitive insulin assay (Cobas e411 immunoassay analyzer; lower detection limit 1.2 pmol/L; normal range 15.1–147.1 pmol/L). Receiver operating characteristics area under the curve (ROC AUC) values and optimal cut-offs were analyzed for the performance of p-insulin to diagnose CHI.ResultsIn 61 CHI patients, the median (range) p-insulin was 76.5 (17–644) pmol/L compared to 1.5 (1.5–7.7) pmol/L in IKH patients (n=15). The ROC AUC was 1.0 for the diagnosis of CHI defined both by the clinical diagnosis (n=61) and by alternative criteria (n=57). The optimal p-insulin cut-offs were 12.3 pmol/L, and 10.6 pmol/L, at p-glucose <3.2 mmol/L (n=61), and <3.0 mmol/L (n=49), respectively.ConclusionsThe sensitive insulin assay performed excellent in diagnosing CHI with optimal p-insulin cut-offs at 12.3 pmol/L (2.0 mU/L), and 10.6 pmol/L (1.8 mU/L), at p-glucose <3.2 mmol/L, and <3.0 mmol/L, respectively. A sensitive insulin assay may serve to simplify the diagnosis of CHI.

Development Of Single -Residue Method To Validate Detection Of Alphacypermethrin

Intention of this research was to develop an analytical technique for analysis of alphacypermethrin (ACYM). It is a pyrethroid insecticide used in agriculture for destroying harmful insects and for killing malaria vector as a public health program. To measure residues of the ACYM in some vegetable samples, a novel method is developed for determination of ACYM. Literatures reveal minimum information about the spectrophotometric determination of ACYM. When ACYM is brominated, it forms dibromoalphacypermethrin which reacts with potassium iodide and potassium iodate in the presence of starch to form blue color dye. The dye show highest absorbance at λmax = 625 nm. Parameters which effect on the reaction were studied and conditions were optimized. Linear calibration curve was obtained from 40 to 120 μg mL-1 ACYM and lower detection limit was 10 μg mL-1. This method was applied on some vegetables and fruit samples for the determination of ACYM.

Investigation of L-Tryptophan Electrochemical Oxidation with a Graphene-Modified Electrode

A graphene sample (EGr) was prepared by electrochemical exfoliation of graphite rods in solution containing 0.05 M (NH4)2SO4 + 0.1 M H3BO3 + 0.05 M NaCl. The exfoliation was performed by applying a constant voltage (12 V) between the graphite rods, while the temperature was kept constant (18 °C) with a temperature-controlled cryostat. The structural investigation of the graphene sample, performed by X-ray powder diffraction (XRD), revealed that the sample consists of a mixture of few-layer (69%), multi-layer graphene (14%) and graphene oxide (17%). In addition, XPS analysis proved that the sample was triple-doped with heteroatoms such as nitrogen (1.7 at%), sulfur (2.5 at%), and boron (3 at%). The sample was deposited onto the surface of a clean, glassy carbon electrode (GC) and investigated for the non-enzymatic electrochemical detection of L-tryptophan (TRP). The electrocatalytic properties of the EGr/GC electrode led to a considerable decrease in the oxidation potential from +0.9 V (bare GC) to +0.72 V. In addition, the EGr/GC electrode has higher sensitivity (two times) and a lower detection limit (ten times) in comparison with the bare GC electrode.

A novel 3D Zn-coordination polymer based on a multiresponsive fluorescent sensor demonstrating outstanding sensitivities and selectivities for the efficient detection of multiple analytes

A Zn-CP exhibits remarkable fluorescence behaviours and stability in a wide range of pH values. It can become an outstanding candidate in the selective sensing of Fe3+, Mg2+, Cr2O72−, MnO4−, NB and NM at a lower detection limit.