Electrochemistry of chalcogen compounds: prediction of antioxidant activity

Synthesis and characterisation of organochalcogens has demonstrated a high correlation between their electrochemical oxidation potential on the glassy carbon electrode, their activity in bioassays and an unprecedented antioxidant activity in neuronal cell culture (EC50 approximately 20 nM) making electrochemical methodology a valuable tool in drug design for Alzheimer's and related diseases.     

基于AuNPs/PANI-NF复合膜的电化学细胞传感器对姜黄素诱导HeLa细胞凋亡的抑制作用检测

以聚苯胺纳米纤维(PANI-NF)-纳米金(AuNPs)复合膜构建传感界面,在AuNPs/PANI-NF界面上修饰转铁蛋白(Tf),利用转铁蛋白与人宫颈癌细胞(HeLa)表面大量表达的转铁蛋白受体(TfR)之间的特异性识别作用,将细胞捕获到传感器界面,导致电化学阻抗值变化。利用电化学阻抗谱研究姜黄素对HeLa细胞的抑制作用。结果表明,随着药物浓度的增大和作用时间的延长,电化学阻抗值下降,表明姜黄素对细胞的抑制作用增强。电化学阻抗值的变化率与药物浓度和作用时间具有量效关系;电化学方法检测显示,姜黄素对HeLa细胞的抑制作用趋势与MTT法及倒置显微镜检测到的姜黄素对HeLa细胞的抑制作用结果相吻合,从而建立了一种检测药物对细胞抑制作用的新方法。该方法具有简便、灵敏度高、费用低廉等优点。     

Electrochemical oxidation by square-wave potential pulses in the imitation of phenacetin to acetaminophen biotransformation

Electrochemistry in combination with mass spectrometry is emerging as a versatile analytical technique in the imitation of oxidative drug metabolism during the early stages of drug discovery and development. Here, we present electrochemical O-dealkylation of phenacetin to acetaminophen by square-wave potential pulses consisting of consecutive sub-second oxidation and reduction steps. This O-dealkylation could not be achieved by oxidation at constant potential or longer potential pulses because of the fast hydrolysis of the reactive intermediates. Electrochemical conversion by square-wave potential pulses can thus widen the scope of electrochemical synthesis of metabolites and imitation of in vivo drug metabolism.     

细胞色素P450酶电化学生物传感器的构建及其药物代谢应用

药物代谢过程是药物在体内产生药效和毒性的主要过程,发展廉价、方便、快速、高通量的体外药物代谢研究方法对新药的开发和设计、给药的方法和剂量、临床药物的检测等都有重要的指导意义. 细胞色素P450酶（CYP450酶）在药物的I相反应中起到关键作用,以电极代替辅酶NADPH提供CYP450酶催化反应过程中需要的两个电子,构建CYP450酶电化学生物传感器可实现药物的初步筛选. 大量研究表明,CYP450酶在电极表面合适的固定方法与电极材料可有效提高传感器的检测性能. 本文主要综述近年来CYP450酶电化学生物传感器的构建及其在药物代谢研究方面的应用,并展望其研发前景.     

Electrochemical parameters and techniques in drug development, with an emphasis on quinones and related compounds

This review article summarizes recent applications of electrochemical techniques to redox-active drug development and mechanistic studies. It includes a general introduction to the use of electrochemistry in biology, with a focus on how electrochemistry can uniquely provide both kinetic and thermodynamic information. A number of studies are reported from the literature and the authors' laboratories, including the investigation of reactive oxygen species, biooxidative/bioreductive activation of pro-drugs, and DNA alkylation, with a particular emphasis on quinones and related compounds. Data from techniques ranging from traditional cyclic voltammetry to sophisticated single cell studies are presented. The examples herein presented illustrate how electrochemical, biochemical and medical knowledge can be integrated to develop strategies for the design and development of redox-selective therapeutics.     

Chitosan/Ionic Liquid Composite Electrode for Electrochemical Monitoring of the Surface‐Confined Interaction Between Mitomycin C and DNA

In the present study a chitosan/ionic liquid modified pencil graphite electrode (CHIT‐IL‐PGEs) was developed for the first time for enhanced electrochemical monitoring of nucleic acid, and the interaction of the anticancer drug Mitomycin C (MC) and calf thymus double stranded DNA (dsDNA) by measuring the oxidation signals of MC and guanine in the same voltammetric scale. Differential pulse voltammetry, cyclic voltammetry and electrochemical impedance spectroscopy techniques were used to evaluate the performance of the CHIT‐IL based biosensor on electrochemical monitoring of DNA, and drug‐DNA interaction. The experimental parameters, IL, dsDNA and MC concentration and the interaction time were then optimized.     

Disclosing the redox metabolism of drugs: The essential role of electrochemistry

Electrochemical methods provide a wide range of strategies to explore the metabolism of drugs. These approaches traditionally encompass preparative aspects viz. the electrochemical generation of potent metabolites or the electrochemical exploration of the reactivity of redox enzymes (or their mimics) toward drugs. More recently, the electroanalytical characterization of the successive redox and redox-coupled reactions was found effective to unravel more complex mechanisms, especially those related to the reactivity of bioorganometallic drugs. This minireview highlights the contribution of these different electrochemical strategies to the determination of drug metabolism through representative recent examples.     

A minisensor for the rapid screening of atenolol in pharmaceutical preparations based on surface-stabilized bilayer lipid membranes with incorporated DNA

This work describes an electrochemical technique that is suitable for the rapid and sensitive screening of atenolol based on surface-stabilized bilayer lipid membranes (s-BLMs) composed from egg phosphatidylcholine (PC). The interactions of atenolol with s-BLMs produced electrochemical ion current increases that reproducible appeared within a few seconds after the exposure of the membranes to the drug. The current signal increase was related to the concentration of atenolol in bulk solution in the micromolar range. The present lipid film-based sensor provided fast response (i.e. on the order of a few seconds) to alterations of atenolol concentration (20 to 200 micro M) in electrolyte solution. ssDNA incorporated into s-BLMs can interact with atenolol, and decreased the detection limit of this drug by one order of magnitude. The oligomers used were single stranded deoxyribonucleic acids: thymidylic acid icosanucleotide terminated with a C-16 alkyl chain to assist incorporation into s-BLMs (5'-hexadecyl-deoxythymidylic acid icosanucleotide, dT(20)-C(16)). The electrochemical transduction of the interactions of atenolol with s-BLMs was applied in the determination of these compounds in pharmaceutical preparations by using the present minisensor.     

CYP450 biosensors based on screen-printed carbon electrodes for the determination of cocaine

A new electrochemical method has been described and characterized for the determination of cocaine using screen-printed biosensors. The enzyme cytochrome P450 was covalently attached to screen-printed carbon electrodes. Experimental design methodology has been performed to optimize the pH and the applied potential, both variables that have an influence on the chronoamperometric determination of the drug. This method showed a reproducibility of 3.56% (n = 4) related to the slopes of the calibration curves performed in the range from 19 up to 166 nM. It has been probed the used of this kind of biosensors in the determination of cocaine in street samples, with an average capability of detection of 23.05 ± 3.53 nM (n = 3, α = β = 0.05).     

Blend films based on biopolymers extracted from babassu mesocarp (Orbignya phalerata) for the electrochemical detection of methotrexate antineoplastic drug

Journal of Solid State Electrochemistry - Methotrexate (MTX) is an antineoplastic drug widely used in cancer therapies with potentially toxic activity. This paper describes the electrochemical...     

A Simple,Efficient and Ultrasensitive Gold Nanourchin Based Electrochemical Sensor for the Determination of an Antimalarial Drug: Mefloquine

Mefloquine (MQ) is a quinoline based antimalarial drug, which is potent against multiple drug‐resistant Plasmodium falciparum . It is widely prescribed for the prophylactic treatment of malaria. Due to extensive usage of MQ, constant monitoring of the drug level in human body is of paramount importancein order to ensure that optimum drug exposure is achieved. The present work describes a gold nanourchins (AuNUs) based electrochemical sensor for the determination of MQ.AuNUs were synthesized via seed‐mediated method and characterized using ultraviolet‐visible spectroscopy, energy‐dispersive X‐ray spectroscopy, field emission scanning electron microscopy, zeta‐sizer and electrochemical techniques (electrochemical impedance spectroscopy and cyclic voltammetry). Fabrication of the sensor was done by drop‐coating the synthesized AuNUs onto a glassy carbon electrode. The fabricated sensor exhibited enhanced voltammetric response, which was attributed to the excellent conductivity and high surface area of AuNUs. Under optimum square wave voltammetric conditions, the sensor displayed two linear response ranges (from 2.0×10⁻⁹ to 1.0×10⁻⁶ M and from 1.0×10⁻⁶ to 1.0×10⁻³ M) with a detection limit of 1.4 nM. The electrode demonstrated good reproducibility, stability and selectivity over common interferents. The utility of the sensor was successfully assessed for quantification of the drug in pharmaceutical preparation and spiked human urine sample. Thus, the present study demonstrates a promising approach for determination of MQ with practical utility in quality control and clinical analysis.     

Three-dimensionally Ordered Macroporous (3DOM) Gold-nanoparticle Doped Titanium Dioxide (GTD) Photonic Crystals Modified Electrodes for Hydrogen Peroxide Biosensor

The design and fabrication of simply,sensitively electrochemical biosensors have been of high interest for their widespread applications such as drug discovery,disease diagnostics,environmental monitoring and food safety.Using the 3DOM GTD/ITO electrode,we developed a new HRP-based H_2O_2 biosensor.This novel H_2O_2 biosensor displayed high sensitivity,acceptable stability and reproducibility.These provide a fundamental theory principle for the new biosensor application.     

Investigation of the mechanism of the electrochemical oxidation of bamipine hydrochloride by voltammetry

The electrochemical oxidation of bamipine hydrochloride in sulphuric acid and phosphate buffer solutions was examined using a platinum electrode. Two different reaction mechanisms for two different potential regions are proposed. It was shown that the determination of the drug by this method is feasible.     

Recent Progress on the Development of Biofuel Cells for Self‐Powered Electrochemical Biosensing and Logic Biosensing: A Review

Biofuel cells (BFCs) based on enzymes and microorganisms have been recently received considerable attention because they are recognized as an attractive type of energy conversion technology. In addition to the research activities related to the application of BFCs as power source, we have witnessed recently a growing interest in using BFCs for self‐powered electrochemical biosensing and electrochemical logic biosensing applications. Compared with traditional biosensors, one of the most significant advantages of the BFCs‐based self‐powered electrochemical biosensors and logic biosensors is their ability to detect targets integrated with chemical‐to‐electrochemical energy transformation, thus obviating the requirement of external power sources. Following my previous review (Electroanalysis­ 2012 , 24, 197–209), the present review summarizes, discusses and updates the most recent progress and latest advances on the design and construction of BFCs‐based self‐powered electrochemical biosensors and logic biosensors. In addition to the traditional approaches based on substrate effect, inhibition effect, blocking effect and gene regulation effect for BFCs‐based self‐powered electrochemical biosensors and logic biosensors design, some new principles including enzyme effect, co‐stabilization effect, competition effect and hybrid effect are summarized and discussed by me in details. The outlook and recommendation of future directions of BFCs‐based self‐powered electrochemical biosensors and logic biosensors are discussed in the end.     

Recent trends and advances in microbial electrochemical sensing technologies: An overview

Microbial electrochemical systems utilize the electrochemical interaction between microorganisms and electrode surfaces to convert chemical energy into electrical energy, offering a promise as technologies for wastewater treatment, bioremediation, and biofuel production. Recently, growing research attention has been devoted to the development of microbial electrochemical sensrs as biosensing platforms. Microbial electrochemical sensors are a type of microbial electrochemical technology (MET) capable of sensing through the anodic or the cathodic electroactive microorganisms and/or biofilms. Herein, we review and summarize the recent advances in the design of microbial electrochemical sensing approaches with a specific overview and discussion of anodic and cathodic microbial electrochemical sensor devices, highlighting both the advantages and disadvantages. Particular emphasis is given on the current trends and strategies in the design of low-cost, convenient, efficient, and high performing METs with different biosensing applications, including toxicity monitoring, pathogen detection, corrosion monitoring, as well as measurements of biological oxygen demand, chemical oxygen demand, and dissolved oxygen. The conclusion provides perspectives and an outlook to understand the shortcomings in the design, development status, and sensing applications of microbial electrochemical platforms. Namely, we discuss key challenges that limit the practical implementation of METs for sensing purposes and deliberate potential solutions, necessary developments, and improvements in the field.     

Advancing the Electrochemistry of the Hydrogen‐Evolution Reaction through Combining Experiment and Theory

The electrocatalytic hydrogen‐evolution reaction (HER), as the main step of water splitting and the cornerstone of exploring the mechanism of other multi‐electron transfer electrochemical processes, is the subject of extensive studies. A large number of high‐performance electrocatalysts have been developed for HER accompanied by recent significant advances in exploring its electrochemical nature. Herein we present a critical appraisal of both theoretical and experimental studies of HER electrocatalysts with special emphasis on the electronic structure, surface (electro)chemistry, and molecular design. It addresses the importance of correlating theoretical calculations and electrochemical measurements toward better understanding of HER electrocatalysis at the atomic level. Fundamental concepts in the computational quantum chemistry and its relation to experimental electrochemistry are also presented along with some featured examples.     

Spontaneous immobilization of liposomes on electron-beam exposed resist surfaces

We have found an interesting immobilization technique of liposomes on electron-beam exposed resist surfaces. The immobilized liposomes have been visualized by the atomic force microscope and have shown well-organized three-dimensional physical structures, in which the liposomes maintain their shapes and sizes similar to those of the original design in prepared solution. The immobilization is based on a strong static charge interaction between the resist surface and the liposomes. Further experiments show that very strong charge in the surfaces produces the firm immobilization of the liposome. We believe these findings can be related to various liposome applications such as drug delivery system, electrochemical or biosensors, and nanoscale membrane function studies.     

Fabrication of nanostructured iron-cobalt layered double hydroxide: An innovative approach for the facile synthesis

Studying semiconductive materials-based supercapacitors is significant for developing next-generation energy storage devices. However, the fabrication of a novel semiconductive material-based electrode with self-supporting design, flexible support, and nanoarchitecture is a challenge for the material researcher of 21st century. We present a facile method to fabricate three-dimensional (3D), porous, conductive electrodes based on semiconductive materials with high electrochemical performance. We fabricate the FeCo-LDH sample via hydrothermal route and decorate it on the flexible carbon cloth (CC) to get a flexible and self-supporting electrode. Textural, morphological, elemental, thermal, and functional group studies of the hydrothermally generated powder were performed using XRD, SEM, EDX, TGA, and FTIR methods. Well-known EIS, GCD, and CV tests were used to evaluate the electrochemical possessions of the FeCo-LDH/CC electrode. The performed electrochemical experiments indicated that our manufactured FeCo-LDH/CC electrode has an excellent specific capacity of 1041F/g at 0.5 A/g. Our self-supporting and flexible electrode has excellent cycle stability (it loses only 7.3 percent of its capacity after 5000 GCD cycles). It retains 79.2 percent of its capacitance when the current density increases from 0.5 A/g to 9 A/g. The superior electrochemical activity observed is attributed to the electrode's novel structure and logical design. According to the electrochemical experiment findings, our manufactured FeCo-LDH/CC electrode has great promise for practical applications in next-generation electrochemical capacitors.     

Influence of reactor design on the electrochemical oxidation and disinfection of wastewaters using boron-doped diamond electrodes

Electrochemical oxidation is the most popular electrochemical advanced oxidation process within the scientific community owing to its simplicity and high effectiveness to treat different wastewaters. Electrode material and reactor design are important factors that influence the removal efficiency of pollutants. This work presents an overview of recent applications of electrochemical oxidation process for contaminant mineralization and water disinfection using electrochemical reactors, in batch and continuous mode of operation, fitted with boron-doped diamond electrodes. In addition, recent advances in the use of flow-through reactors (continuous single-pass and recirculation) are presented. Geometrical aspects, operating conditions, and energy consumption are provided and discussed.