Electrochemical Determination of Rate Constants for Reactions of OH and its Application in the Evaluation of Anti-Oxidant Actions of Rheum

A single-sweep oscillopolarographic procedure is descrital which allows detethenahon of rateconstants for reachons of oH. For a wide range of compounds, the results fit well with rate constantspreviously obtained with other methods. Rate constants for reactions of six kinds of active compoundscontalned in rheum, a tradihonal Chinese herb, have been deteboned by this method. Rcationmechanism ha5 also been discussed.

Electrochemically Reduced Graphene Oxide as Modified Electrode Material for Determination of Dihydroxybenzenes

A simple and green method was introduced to fabricate the electrochemical sensor based on the electrochemically reduced graphene oxide（ERGO） modified electrode. It was found that the ERGO modified electrode exhibited an excellent catalytic activity toward the oxidation of dihydroxybenzenes isomers. Under the optimum conditions, in the simultaneous determination of the dihydroxybenzene isomers, the currents were linear with the concentrations of the isomers from 5 to 550 μmol/L for hydroquinone（HQ）, from 6 to 400 μmol/L for catechol（CT） and from 5 to 350 μmol/L for resorcinol（RS）, respectively. In addition, the proposed sensor has good stability and reproducibility. The developed method has been applied to the simultaneous determination of dihydroxybenzene isomers in real samples with a satisfactory recovery from 98% to 103%.

Research Surveys of Electrochemical Sensors for in-situ Determining Hydrogen in Steels

The principle, construction and application of two types of electrochemical sensors-amperometric and potentiometric are surveyed. Both types of sensors are very sensitive to changes in temperature. The accuracy of hydrogen measurement depends on both the precision of sensors developed and the reliable technique of installation and security of sensors. The two types of sensors have been used for in-situ determining hydrogen permeated in steels owing to a corrosive reaction, a hydrogen gas circumstance at elevated temperatures and high pressure or also a pretreatment process such as pickling and plating process, etc.

Electrochemical sensor based on f-SWCNT and carboxylic group functionalized PEDOT for the sensitive determination of bisphenol A

A simple, sensitive, and reliable method for the voltammetric determination of bisphenol A （BPA） by using carboxylic group functionalized single-walled carbon nanotubes （f-SWCNT）/carboxylic-functionalized poly（3,4-ethylenedioxythiophene） （PC4） complex modified glassy carbon electrode （GCE） has been successfully developed. The electrochemical behavior of BPA at the surface of the modified electrode is investigated by electrochemical techniques. The cyclic voltammetry results show that the as-prepared electrode exhibits strong catalytic activity toward the oxidation of BPA with a well-defined anodic peak at 0.623 V in PBS （0.1 mol/L, pH 7.0）. The surface morphology of the 3D network of composite film is beneficial for the adsorption ofanalytes. Under the optimized conditions, the oxidation peak current is proportional to BPA concentration in the range between 0.099 and 5.794 μmol/L （R2 = 0.9989）, with a limit of detection of 0.032 μmol/L （SIN = 3）. The enhanced performance of the sensor can be attributed to the excellent electrocatalytic property off-SWCNT and the extraordinary conductivity of PC4. Furthermore, the proposed modified electrode displays high stability and good reproducibility. The good result on the voltammetric determination of BPA also indicates that the asfabricated modified electrode will be a good candidate for the electrochemical determination and analysis of BPA.

Phenotype-Directed DNA Nanomachine for in Situ Analysis of Stem Cell-like Subpopulation in Breast Cancer

The cancer stem cell hypothesis provides a basis for prediction of the recurrence and risk of metastasis in breast cancer.However,the unique expression pattern of stemness markers and the presence of nonstem-like cancer cells with varied phenotypes have brought great challenges to the characterization of breast cancer stem cells.To address these challenges,a phenotype-directed DNA nanomachine has been designed for high-accuracy labeling and in situ analysis of the stem cell-like subpopulation in breast cancer.The key for the design is to use cell surfaceanchored inputs to activate the nanomachine,which undergoes different branch migration pathways such that the signal strand can only be brought onto the cancer cells having the stem cell-like phenotype.Highly sensitive determination and single-step isolation of the stem cell-like subpopulation were achieved by incorporating functional groups into the signal strand such that the nanomachine was successfully applied in a tumor-bearing mouse model.Overall,the approach provides for a substantial improvement in capability for the analysis of the breast cancer stem cell-like subpopulation,and it is expected that the new approach will advance the use of DNA nanomachines in cancer-related studies.

Preparation of Nanosized CoHCF Modified Electrode and Its Application to Electroanalysis of Hemoglobin

A cobalt hexacyanoferrate （CoHCF） nanoparticle （size ca. 60 nm） chemically modified electrode （CME） was fabricated and the electrochemical behavior of hemoglobin （Hb） at this nanosized CoHCF CME was studied. In comparison with a bare glassy carbon electrode （GCE） and a general CoHCF CME electrodeposited in a traditional manner, the present nanosized CoHCF CME performed efficiently electrocatalytic reduction for Hb with relatively high sensitivity, stability, and longlife, Combined with liquid chromatography （LC）, the nanosized CoHCF CME was used as the electrochemical detector of Hb in the established flow injection analysis-electrochemical determination （FIA-ECD） system. The peak current was a linear function of concentrations in the range from 2.5×10^-8 to 5.0×10^-6mol/L for Hb, with detection limit of 1.4×10^-8 mol/L. The FIA-ECD system has been successfully applied to assess the Hb content of clinic blood samples with advantages of sensitiveness, speediness, easy control and small sample-consumption.

Voltammetric response of ferroceneboronic acid to diol and phenolic compounds as possible pollutants

A voltammetric determination of possible organic pollutants such as diol and phenolic compounds in water was studied using ferroceneboronic acid（FBA） as a redox-active marker.A cyclic voltammogram of FBA exhibited a pair of oxidation and reduction peaks at 230 and 170 mV at pH 7.0,respectively,while another pair of redox peaks was observed in the presence of diol or phenolic compounds tested.The results were rationalized based on the formation of boronate esters of FBA with the added compounds.The changes in the redox peak currents were dependent on the concentration of the additives,suggesting a usefulness of FBA in the electrochemical determination of these compounds in water.