Two copper(II)-bbtz modified Keggin and β-octamolybdate compounds captured in one-pot under hydrothermal conditions

Under hydrothermal conditions two compounds based on Keggin and β-octamolybdate, respectively, [Cu₂(bbtz)₄(SiMo₁₂O₄₀)] (1) and [Cu₂(bbtz)₄(Mo₈O₂₆)]_1/2·H₂O (2) (bbtz = 1,4-bis(1,2,4-triazol-1-ylmethyl)benzene), were synthesized in one-pot and characterized by single-crystal X-ray diffraction, elemental analyses, and IR spectroscopy. In compound 1, two adjacent wave-like Cu^II-bbtz lines are connected by SiMo₁₂ anions and bbtz to generate a ladder-like chain. Adjacent chains share the same Cu^II ions to build a three-dimensional (3-D) framework. In compound 2, the β-Mo₈ anions link Cu₃(bbtz)₂ subunits alternately to form a one-dimensional (1-D) chain. These chains connect each other through sharing Cu^II ions and a 3-D network is constructed. Moreover, we studied the electrocatalytic and photocatalytic activities of these two compounds. The results indicate that 1 and 2 show good electrocatalytic performance for the reduction of nitrite and bromate; they also exhibit photocatalytic properties for degradation of MB and RhB.     

Construction of a novel electrochemical sensor based on molecularly imprinted polymers for the selective determination of chlorpyrifos in real samples

We present a novel electrochemical sensor based on an electrode modified with molecularly imprinted polymers for the detection of chlorpyrifos. The modified electrode was constructed by the synthesis of molecularly imprinted polymers by a precipitation method then coated on a glassy carbon electrode. The surface morphology of the modified electrode was characterized by using field‐emission scanning electron microscopy and transmission electron microscopy. The performance of the imprinted sensor was thoroughly investigated by using cyclic voltammetry and differential pulse voltammetry. The imprinted electrochemical sensor displayed high repeatability, stability, and selectivity towards the template molecules. Under the optimal experimental conditions, the peak current response of the imprinted electrochemical sensor was linearly related to the concentration of chlorpyrifos over the range 1 × 10⁻¹⁰–1 × 10⁻⁵ mol/L with a limit of detection of 4.08 × 10⁻⁹ mol/L (signal‐to‐noise ratio = 3). Furthermore, the proposed molecularly imprinted electrochemical sensor was applied to the determination of chlorpyrifos in the complicated matrixes of real samples with satisfactory results. Therefore, the molecularly imprinted polymers based electrochemical sensor might provide a highly selective, rapid, and cost‐effective method for chlorpyrifos determination and related analysis.     

Electrochemical Peptide-Based Sensors for Foodborne Pathogens Detection

Food safety and quality control pose serious issues to food industry and public health domains, in general, with direct effects on consumers. Any physical, chemical, or biological unexpected or unidentified food constituent may exhibit harmful effects on people and animals from mild to severe reactions. According to the World Health Organization (WHO), unsafe foodstuffs are especially dangerous for infants, young children, elderly, and chronic patients. It is imperative to continuously develop new technologies to detect foodborne pathogens and contaminants in order to aid the strengthening of healthcare and economic systems. In recent years, peptide-based sensors gained much attention in the field of food research as an alternative to immuno-, apta-, or DNA-based sensors. This review presents an overview of the electrochemical biosensors using peptides as molecular bio-recognition elements published mainly in the last decade, highlighting their possible application for rapid, non-destructive, and in situ analysis of food samples. Comparison with peptide-based optical and piezoelectrical sensors in terms of analytical performance is presented. Methods of foodstuffs pretreatment are also discussed.     

Adsorptive Cathodic Stripping Voltammetry for Quantification of Alprazolam

A simple and highly sensitive electrochemical sensor was developed for adsorptive cathodic stripping voltammetry of alprazolam. Based on an electrochemically pretreated glassy carbon electrode, the sensor demonstrated good adsorption and electrochemical reduction of alprazolam. The morphology of the glassy carbon electrode and the electrochemically pretreated glassy carbon electrode were characterized by scanning electron microscopy/energy dispersive X-ray spectroscopy, Fourier transform infrared spectroscopy, cyclic voltammetry, and electrochemical impedance spectroscopy. The electrochemical behaviors of alprazolam were determined by cyclic voltammetry, and the analytical measurements were studied by adsorptive cathodic stripping voltammetry. Optimized operational conditions included the concentration and deposition time of sulfuric acid in the electrochemical pretreatment, preconcentration potential, and preconcentration time. Under optimal conditions, the developed alprazolam sensor displayed a quantification limit of 0.1 mg L⁻¹, a detection limit of 0.03 mg L⁻¹, a sensitivity of 67 µA mg⁻¹ L cm⁻² and two linear ranges: 0.1 to 4 and 4 to 20 mg L⁻¹. Sensor selectivity was excellent, and repeatability (%RSD < 4.24%) and recovery (82.0 ± 0.2 to 109.0 ± 0.3%) were good. The results of determining alprazolam in beverages with the developed system were in good agreement with results from the gas chromatography–mass spectrometric method.     

The Influence of Water Vapor on the Electrochemical Shift of an Ionic Liquid Measured by Ambient Pressure X-ray Photoelectron Spectroscopy

Ionic liquids (ILs) are considered to be one of the steppingstones to fabricate next generation electrochemical devices given their unique physical and chemical properties. The addition of water to ILs significantly impact electrochemical related properties including viscosity, density, conductivity, and electrochemical window. Herein we utilize ambient pressure X-ray photoelectron spectroscopy (APXPS) to examine the impact of water on values of the electrochemical shift (S), which is determined by measuring changes in binding energy shifts as a function of an external bias. APXPS spectra of C 1s, O 1s and N 1s regions are examined for the IL 1-butyl-3-methylimidazolium acetate, [C₄mim][OAc], at the IL/gas interface as a function of both water vapor pressure and external bias. Results reveal that in the absence of water vapor there is an IL ohmic drop between the working electrode and quasi reference electrode, giving rise to chemical specific S values of less than one. Upon introducing water vapor, S values approach one as a function of increasing water vapor pressure, indicating a decrease in the IL ohmic drop as the IL/water mixture becomes more conductive and the potential drop is driven by the electric double layer at the electrode/IL interface.     

微纳电化学传感界面的构建及其用于单细胞实时监测

细胞是生物体形态结构和生命活动的基本单位.常规检测群体细胞的方法往往会掩盖细胞间的个体差异,因此亟需发展高效的单细胞分析策略,深入研究细胞生命活动过程,揭示疾病发生发展机制,推动个体化诊疗.超微电化学传感器具有尺寸小、灵敏度高、时空分辨率高等特点,在单细胞实时动态监测方面发挥了非常重要的作用.目前,微纳电化学传感器在电极制备、高性能传感界面构建、理论分析等方面已取得重要进展,且在单细胞实时监测及相关细胞机制研究方面取得突破.然而,单细胞内环境复杂、活性分子浓度低且随时空高度动态变化,这对微纳电化学传感器的灵敏度和选择性等综合性能提出了更高要求.我们课题组长期从事基于微纳电化学传感的单细胞与亚细胞实时动态监测研究,本文主要介绍了我们近10年来在该领域的研究进展,并对未来的挑战与机遇进行了探讨.     

Facile Surfactant-, Reductant-, and Ag Salt-free Growth of Ag Nanoparticles with Controllable Size from 35 to 660 nm on Bulk Ag Materials

Morphologically and dimensionally controlled growth of Ag nanocrystals has long been plagued by surfactants or capping agents that complicate downstream applications, unstable Ag salts that impaired the reproducibility, and multistep seed injection that is troublesome and time-consuming. Here, we report a one-pot electro-chemical method to fast (∼2 min) produce Ag nanoparticles from commercial bulk Ag materials in a nitric acid solution, eliminating any need for surfactants or capping agents. Their size can be easily manipulated in an unprecedentedly wide range from 35 to 660 nm. Furthermore, the Ag nanoparticles are directly grown on the Ag substrate, highly desirable for promising applications such as catalysis and plasmonics. The mechanistic studies reveal that the concentration of Ag⁺ in the diffusion layer nearby the surface, controlled by the magnitude and duration of voltage, is critical in governing the nanoparticle formation (<1.3 mM) and its dimensional adjustability.     

电化学传感分析平台测定污水中的Cr(VI)

结合微型电化学仪器,研究了一种快速、便携、灵敏的Cr(VI)电化学传感分析平台,用于污水中Cr(VI)的检测。采用三电极体系,差分脉冲阴极溶出伏安法(DPCSV),记录伏安曲线中Cr(VI)的还原峰。Cr(VI)的溶出峰电流与其浓度在2～500 μmol L-1范围内有良好的线性关系,测得Cr(VI)的检测限为0.55 μmol L-1 (28.60 g L-1),达到了国际卫生组织（WHO）规定的饮用水中Cr(VI)的最高含量50 g L-1。测得镀铬厂废水中Cr(VI)含量为2.03 mol L-1,与国标法中光谱学分析法的结果基本一致。该法重现性好、灵敏度高,使其应用在现场实时监测环境中的Cr(VI)具有很大的潜力。     

Electrochemical aptamer sensor for highly sensitive detection of mercury ion with Au/Pt@carbon nanofiber‐modified electrode

In this paper, an electrochemical aptamer sensor was proposed for the highly sensitive detection of mercury ion (Hg²⁺). Carbon nanofiber (CNF) was prepared by electrospinning and high‐temperature carbonization, which was used for the loading of platinum nanoparticles (PtNPs) by the hydrothermal method. The Pt@CNF nanocomposite was modified on the surface of carbon ionic liquid electrode (CILE) to obtain Pt@CNF/CILE, which was further decorated by gold nanoparticles (AuNPs) through electrodeposition to get Au/Pt@CNF/CILE. Self‐assembling of the thiol‐based aptamer was further realized by the formation of Au‐S bond to get an electrochemical aptamer sensor (Aptamer/Au/Pt@CNF/CILE). Due to the specific binding of aptamer probe to Hg²⁺ with the formation of T‐Hg²⁺‐T structure, a highly sensitive quantitative detection of Hg²⁺ could be achieved by recording the changes of current signal after reacting with Hg²⁺ within the concentration range from 1.0 × 10^?15 mol/L to 1.0 × 10^?6 mol/L and the detection limit of 3.33 × 10^?16 mol/L (3σ). Real water samples were successfully analyzed by this method.     

Controllable Preparation of Nanosized LiMnPO4/C with Rod-Like Morphology by Hydrothermal Method with Excellent Electrochemical Performance

The nanosized rod-like LiMnPO₄/C cathode materials have successfully in situ synthesized on the surface of flaky structure MnPO₄ · H₂O self-sacrificing template by the hydrothermal method. The crystal microstructure, micro shape, and electrochemical parameters of LiMnPO₄/C are comprehensively studied by XRD, SEM, TEM, and electrochemical measurement methods. The physical and chemical properties analysis confirms that the vinyl acetate solution (VAc-H₂O) with a proper molar ratio is beneficial to generate orthorhombic olivine structure LiMnPO₄ with microporous structure and nanorod-shaped morphology. The electrochemical measurement results indicate that LMP-X1-AA sample delivers an initial discharge capacity of 148.1 mAh g⁻¹ at 0.05 C, the capacity retention rate still maintains at 89.2% after 200 cycles. As the discharge rate increases to 1 C, the discharge capacity still remains at 133.4 mAh g⁻¹. The results indicate that the synergistic effect of nanosized rod-like morphology and conductive carbon coating is beneficial to improving the lithium ions diffusivity and electrochemical properties of LiMnPO₄ materials.