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A novel, economic, and highly sensitive electrochemical sensor for the determination of trans-resveratrol (RES) was fabricated by electropolymerization of poly(L-lysine) films onto glassy carbon electrode (GCE) surface. The electrochemical behavior of RES in Britton-Robinson buffer solution (pH 2.0) on the poly(L-lysine)/GCE was investigated by cyclic voltammetry and linear sweep voltammetry for the first time. Results showed that the detection range of the proposed sensor to RES was from 0.20 to 12.0 [mu]M with the minimum detectable concentration of 0.06 [mu]M. The reported electrochemical sensor also exhibited high selectivity, good reproducibility, and long-term stability for RES detection. In addition, the proposed method can be employed for the determination of RES in red wines with satisfactory results. The proposed electrochemical strategy presents valuable information related to evaluation of RES levels in real samples., Author(s): Congming Li [sup.1], Yanli Zhou [sup.1] [sup.2], Baoxian Ye [sup.1], Maotian Xu [sup.1] [sup.2] Author Affiliations: (1) grid.207374.5, 0000 0001 2189 3846, College of Chemistry and Molecular Engineering, Zhengzhou [...]

A signal‐off aptasensor was described based on well‐designed aptamer‐Cu3(PO4)2 hybrid nanoflowers&graphene oxide composites (aptamer‐Cu3(PO4)2HNF&GO) as an effective sensing platform and molybdophosphate precipitation as the signaling element. The aptamer, as the biorecognition unit grafted on aptamer‐Cu3(PO4)2HNF&GO by the specificity of streptavidin and biotin, captured the carcinoembryonic antigen (CEA) through specific interaction. The molybdophosphate precipitation were formed by the reaction of the aptamer‐Cu3(PO4)2HNF&GO with molybdate (MoO42−). However, the CEA‐aptamer bioconjugate layer films not only hinder electron transfer on the sensing interface, but also impede the formation of molybdophosphate precipitation, resulting that the current signal significantly decreased. So, a simple aptasensor for CEA was constructed with high sensitivity and signal‐off model. Under optimal experimental conditions using square wave voltammetry (SWV), the response peak currents decreases linearly with the logarithm of CEA concentrations in the range from 10 fg mL−1 to 500 ng mL−1. Also, the feasibility of its applications has also been demonstrated in the analysis of clinical serum samples. [ABSTRACT FROM AUTHOR]

Four novel tetranuclear macrocyclic compounds [Cd2(η2-O2CFcCO2)2(2,2′-bpy)2(H2O)2] · 2H2O (1), [Zn2(η2-O2CFcCO2)2(2,2′-bpy)2(H2O)2] · CH3OH · H2O (2), [Co2(O2CFcCO2)2(2,2′-bpy)2(μ2-OH2)2] · CH3OH · 2H2O (3), and [Ni2(O2CFcCO2)2(2,2′-bpy)2(μ2-OH2)2] · CH3OH · 2H2O (Fc=(η5-C5H4)Fe(η5-C5H4) (4) have been synthesized and structurally characterized by single crystal diffraction. The magnetic behaviors for compounds (3) and (4) are studied in the temperature range of 5.0–300 K. The results show that the antiferromagnetic coupling of CoII–CoII pairs occurs in (3), and unusual global ferromagnetic coupling between nickel (II) ions exists in (4). The solution-state differential pulse voltammetries of compounds (1)–(4) all show two peaks with large separations (ΔE) that indicate strong interactions between two ferrocene moieties. Their fluorescent and thermal properties were also investigated. [Copyright &y& Elsevier]

Oxidative stress plays an important role in the pathogenesis of many diseases, while the exact mechanism that hydrogen peroxide (H 2 O 2 ) as one of the most abundant reactive oxygen species (ROS) exerts its influence on oxidative stress remains unclear. We developed a novel turn-on ratiometric electrochemical sensor for the detection of H 2 O 2 in blood samples. The electrochemical probe 5-(1,2-dithiolan-3-yl)-N-(4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)phenyl)pent-anamide (BA) was designed and synthesized for the selective detection of H 2 O 2 via a one-step amide reaction. Meanwhile, Nile Blue A (NB) was optimized as an internal reference molecule, thus enabling accurate quantification of H 2 O 2 in a complex environment. BA and NB were then co-assembled onto a carbon fiber microelectrode (CFME) coated with Au cones. The oxidation peak current ratio between BA and NB demonstrated good linearity with the logarithm of the H 2 O 2 concentration values ranging from 0.5 μM to 400 μM with a low detection limit of 0.02 μM. The developed sensor showed remarkable selectivity against potential interferences in whole blood samples, especially for ascorbic acid, uric acid, and dopamine. In combination with the unique characteristics of CFME, such as a small size and good biocompatibility, the microsensor was used for rapid analysis of one drop of whole blood sample. This sensor not only creates a new platform for the detection of H 2 O 2 in whole blood samples, but also provides a new design strategy of other ROS analysis for early diagnosis of ROS-related diseases, drug discovery processes, and pathological mechanisms., (Copyright © 2020 Elsevier B.V. All rights reserved.)

A novel signal on-off type photoelectrochemical (PEC) biosensing system was designed for sensitive detection of carcinoembryonic antigen (CEA) based on tin disulfide nanosheets loaded on reduced graphene cxide (SnS 2 -GR) as the photoactive material and gold nanoparticles coated on reduced graphene oxide-functionalized copper sulfide (Au@CuS-GR) for signal amplification. It's the first time for SnS 2 -GR was exploited as a sensing matrix. Here, the photocurrent signals of SnS 2 were amplified attributed to the sensitization effect of graphene. As signal amplifier, Au@CuS-GR could quench the photocurrents of SnS 2 -GR not only through the p-n type semiconductor quenching effect as well as the steric hindrance effect, but also as peroxidase mimetics to catalyze the oxidation of 4-Chloro-1-naphthol (4-CN) to produce insoluble product on the electrode surface. Based on the multiple signal amplification ability of Au@CuS-GR, CEA was detected sensitively with a linear range from 0.1 pg mL -1 to 10 ng mL -1 and limit of detection down to 59.9 fg mL -1 (S/N = 3). Meanwhile, the PEC biosensor displayed excellent performance in the assay of human serum sample, showing good application prospects for various target analysis., (Copyright © 2019 Elsevier B.V. All rights reserved.)