Porous Ni3N nanosheet array as a catalyst for nonenzymatic amperometric determination of glucose

A new formulation of Ni/Zn bi-metallic nanocomposite and evaluation of its applications for pollution removal, photocatalytic, electrochemical sensing, and anti-breast cancer

Nanocomposites have gained attention due to their variety of applications in different fields. In this research, we have reported a green synthesis of a bi-metallic nanocomposite of nickel and zinc using an aqueous extract of Citrus sinensis in the presence of chitosan (Ni/Zn@orange/chitosan). The nanocomposite was characterized using different techniques. We have examined various applications for Ni/Zn@orange/chitosan. The NPs were manufactured in spherical morphology with a particle range size of 17.34-90.51 nm. Ni/Zn@orange/chitosan showed an acceptable ability to remove dyes of Congo red and methyl orange from an aqueous solution after 80 min furthermore, it uptaking the drug mefenamic acid from a solution. Ni/Zn@orange/chitosan also exhibited great photocatalytic activity in synthesizing benzimidazole using benzyl alcohol and o-phenylenediamine. Ni/Zn@orange/chitosan was found as a potent electrochemical sensor to determine glucose. In the molecular and cellular section of the current research, the cells with composite nanoparticles were studied by MTT way about the anti-breast adenocarcinoma potentials malignant cell lines. The IC50 of composite nanoparticles were 320, 460, 328, 500, 325, 379, 350, and 396 μg/mL concering RBA, NMU, SK-BR-3, CAMA-1, MCF7, AU565, MDA-MB-468, and Hs 281.T breast adenocarcinoma cell lines, respectively. The results revealed the newly synthesized nanocomposite is a potent photocatalyst, dye pollution removal agent, and an acceptable new drug to treat breast cancer.

Bismuth Nanoclusters/Porous Carbon Composite: A Facile Ratiometric Electrochemical Sensing Platform for Pb2+ Detection with High Sensitivity and Selectivity

In this work, a ratiometric electrochemical sensor was constructed for the detection of Pb²⁺ based on a bismuth nanocluster-anchored porous activated biochar (BiNCs@AB) composite. BiNCs with loose structure and AB with abundant oxygen-containing functional groups are favorable for Pb²⁺ adsorption and preconcentration; meanwhile, porous AB provides more mass transfer pathways and increases electronic and ion diffusion coefficients, realizing high sensitivity for Pb²⁺ detection. At the same time, BiNCs were proposed as an inner reference for ratiometric electrochemical detection, which could greatly enhance the determination accuracy. Under optimized experimental conditions, the anodic peak current ratio between Pb²⁺ and BiNCs exhibited a good linear relationship with the concentration from 3.0 ng/L to 1.0 mg/L. The detection limit can be detected down to 1.0 ng/L. Furthermore, the proposed sensor demonstrated good reproducibility, stability, and interference resistance, as well as satisfactory recoveries for the detection of Pb²⁺ in real samples.

Electrochemical assay of ampicillin using Fe3N-Co2N nanoarray coated with molecularly imprinted polymer

Self-supported Fe₃N-Co₂N nanoarray with high electric conductivity and large surface area was prepared for growth of MIPs and further constructing a sensitive and stable electrochemical sensor. For the evaluation of its performance, Fe₃N-Co₂N is used as sensing electrode material, and AMP is used as template molecule to construct the MIP electrochemical sensor. Under the optimized conditions, the developed MIPs electrochemical sensor detects AMP with a low detection limit of 3.65 × 10^-10 mol L^-1 and shows outstanding reproducibility and stability. When the MIPs electrochemical sensor was applied to detect AMP in milk samples via standard addition method, the recovery within 97.06-102.43% with RSD of 1.05-2.11% was obtained. The fabrication of MIPs electrochemical sensor is highly promising for sensitive and selective electrochemical measurement and food safety testing. This work can provide theoretical guidance for truly challenging problems. Graphical abstract Principle diagram of MIP-EC sensor for detecting AMP Molecular imprinted polymers (MIPs) are widely performed for construction of electrochemical (EC) sensors especially for detecting small molecules in complex environment. However, the large-scale and robust preparation of MIPs in situ on sensor platform limits their practical applications. We fabricated a MIPs EC sensor based on Fe₃N-Co₂N in situ grown on carbon cloth (CC) as the substrate platform (Fe₃N-Co₂N/CC) combining with MIPs as the target recognition element for the label-free detection of AMP. Under the optimal conditions, the developed MIPs EC sensor can detect AMP with a low detection limit of 3.65 × 10^-10 mol L^-1. When the AMP in milk is detected by the proposed EC sensor, it shows ideal results. Therefore, the use of self-supported Fe₃N-Co₂N nanoarray as the platform for the fabrication of MIPs EC sensors is highly promising for sensitive and selective EC measurement and point-of-care testing.

Cobalt-copper bimetallic nanostructures prepared by glancing angle deposition for non-enzymatic voltammetric determination of glucose

A bimetallic nanostructure of Co/Cu for the non-enzymatic determination of glucose is presented. The heterostructure includes cobalt thin film on a porous array of Cu nanocolumns. Glancing angle deposition (GLAD) method was used to grow Cu nanocolumns directly on a fluorine-doped tin oxide (FTO) substrate. Then a thin film of cobalt was electrodeposited on the Cu nanostructures. Various characterization studies were performed in order to define the optimum nanostructure for the determination of glucose. The results showed remarkable boosting of the electrocatalytic activity of Co/Cu bimetallic structure compare to the responses achieved by the monometallic structures of Co or Cu. The sensor showed two linear response ranges for the determination of glucose at 0.55 V in 0.1 M NaOH, from 5 μM-1 mM and 2-9 mM. The sensitivity was 1741 (μA mM^-1 cm^-2) and 626 (μA mM^-1 cm^-2), respectively, while the detection limit for a signal-to-noise ratio of 3 was found to be 0.4 μM. The sensor exhibited excellent selectivity and was successfully applied to the determination of glucose in real human blood serum samples. Graphical Abstract Schematic representation of fabrication process of the glucose sensor of Co (Cobalt)/Cu (Copper) on Fluorine doped Tin Oxide (FTO). The current voltage plots show higher electrooxidation activity of the bimetallic nanostructure of Co/Cu/FTO relative to the bare Co/FTO.

Nanostructured nickel oxide electrodes for non-enzymatic electrochemical glucose sensing

Nanostructured nickel (Ni) and nickel oxide (NiO) electrodes were fabricated on Ni foils using the glancing angle deposition (GLAD) technique. Cyclic voltammetry and amperometry showed the electrodes enable non-enzymatic electrochemical determination of glucose in strongly alkaline media. Under optimized conditions of NaOH concentration and working potential (~ 0.50 V vs. Ag/AgCl), the GLAD electrodes performed far better than bare Ni foil electrodes, with the GLAD NiO electrode showing an outstanding sensitivity (4400 μA mM^-1 cm^-2), superior detection limit (7 nM), and wide dynamic range (0.5 μM-9 mM), with desirable selectivity and reproducibility. Based on their performance at a low concentration, the GLAD NiO electrodes were also used to quantify glucose in artificial urine and sweat samples which have significantly lower glucose levels than blood. The GLAD NiO electrodes showed negligible response to the common interferents in glucose measurement (uric acid, dopamine, serotonin, and ascorbic acid), and they were not poisoned by high amounts of sodium chloride. Graphical abstract The figures depict (A) SEM image of vertical post-GLAD NiO electrodes used for non-enzymatic electrochemical glucose monitoring, and (B) calibration plots of the three different electrodes.

A nickel-cobalt bimetallic phosphide nanocage as an efficient electrocatalyst for nonenzymatic sensing of glucose

The authors describe Ni-Co bimetal phosphide (NiCoP) nanocages that exhibit enhanced electrocatalytic performance toward glucose oxidation. The nanocages offer an appealing architecture, large specific area, and good accessibility for the analyte glucose. When placed on a glassy carbon electrode, the sensor exhibits attractive figures of merit for sensing glucose in 0.1 M NaOH solution including (a) a wide linear range (0.005-7 mM), (b) a low determination limit (0.36 μM), (c) high sensitivity (6115 μA•μM^-1•cm^-2), (d) a relatively low working potential (0.50 V vs. Ag/AgCl), and (e) good selectivity, reproducibility, and stability. The sensor is successfully applied to the determination of glucose in human serum samples. Graphical abstractSchematic representation of a glassy carbon electrode modified with Ni-Co bimetal phosphide (NiCoP) nanocage. NiCoP nanocage exhibits excellent electrocatalytic activity toward glucose oxidation. NiCoP nanocage is applied in a sensitive non-enzymatic glucose sensor.

Synthesis of porous Co3S4 for enhanced voltammetric nonenzymatic determination of glucose

Porous Co₃S₄ was synthesized by a two-step hydrothermal method, and its morphology and structure were characterized by transmission electron microscopy and X-ray diffraction. Electrochemical investigations showed that a glassy carbon electrode modified with Co₃S₄ exhibits high electrocatalytic activity toward glucose in 0.2 M NaOH solution. Figures of merit for this sensor include (i) a wide linear range (2.0 μM to 1.1 mM), (ii) a working potential near 0.52 V (vs. Ag/AgCl), (iii) high sensitivity (346.7 μA mM^-1 cm^-2), and (iv) a 0.17 μM detection limit. Graphical abstractPorous Co₃S₄ was explored as electrocatalyst for glucose oxidation. It exhibits distinctly higher electrocatalytic activity toward glucose oxidation than Co₃O₄.

A non-enzymatic amperometric glucose sensor based on the use of graphene frameworks-promoted ultrafine platinum nanoparticles

Ultrafine platinum nanoparticles are grown on a 3D graphene framework (GF-Pt) via a hydrothermal method. The material, when placed on a glassy carbon electrode (GCE), displays enhanced electrocatalytic activity towards glucose oxidation. This is assumed to be the result of the numerous easily accessible active sites, an enlarged electrochemically active area, and the presence of multiple electron/ion transport channels. The modified GCE can be operated at a low potential (- 0.15 V vs. Ag/AgCl) has linear responses in the 0.1 μM - 0.01 mM and 0.01 mM - 20 mM glucose concentration range, and a 30 nM detection limit. It was applied to the rapid determination of glucose in human serum samples. Graphical abstract Schematic presentation of a glassy carbon electrode modified with ultrafine Pt nanoparticles grown on a graphene framework (GFs-Pt). GFs-Pt presents enhanced electrocatalytic activity towards glucose oxidation. GFs-Pt is used in a sensitive non-enzymatic amperometric glucose sensor.

Electrochemical determination of the activity and inhibition of telomerase based on the interaction of DNA with molybdate

An ultrasensitive electrochemical sensor is described for the determination of the activity of telomerase. It is based on a DNA-generated current that is due to the reaction of the phosphate groups on DNA with molybdate to form a redox-active molybdophosphate. A telomerase substrate primer was first immobilized on a gold electrode. In the presence of telomerase and deoxyribonucleoside triphosphates (dNTPs), the primer can be extended with repetitive nucleotide sequences (TTAGGG). The subsequent reaction of the sensor with molybdate results in the enhancement of electrochemical current intensity due to an increased amount of nucleotides on the electrode. Sensitivity can be further improved by introducing a hairpin probe that partially hybridizes with the repetitive TTAGGG sequence and further enhances the amount of DNA on the electrode. The biosensor, best operated at 0.2 V (vs. Ag/AgCl) shows a linear response to telomerase activity from 1×10² to 10⁷ Hela cells mL^-1. The assay was applied to the detection of telomerase activity in HeLa cancer cells treated with the anticancer drug epigallocatechin gallate, and the results indicate that it holds great potential in anticancer drug screening. Graphical abstract Schematic presentation of an ultrasensitive electrochemical sensor for the determination of telomerase activity based on DNA generated electrochemical current. dNTPs in the scheme represents deoxyribonucleoside triphosphates.