Baoxian Ye

A combination of modified particle swarm optimization algorithm and support vector machine for gene selection and tumor classification.

In the analysis of gene expression profiles, the number of tissue samples with genes expression levels available is usually small compared with the number of genes. This can lead either to possible overfitting or even to a complete failure in analysis of microarray data. The selection of genes that are really indicative of the tissue classification concerned is becoming one of the key steps in microarray studies. In the present paper, we have combined the modified discrete particle swarm optimization (PSO) and support vector machines (SVM) for tumor classification. The modified discrete PSO is applied to select genes, while SVM is used as the classifier or the evaluator. The proposed approach is used to the microarray data of 22 normal and 40 colon tumor tissues and showed good prediction performance. It has been demonstrated that the modified PSO is a useful tool for gene selection and mining high dimension data.

Determination of caffeine content in tea based on poly(safranine T) electroactive film modified electrode.

Safranine T was electropolymerised on a glassy carbon electrode and then characterised by scanning electron microscope (SEM), X-ray diffraction (XRD) and electrochemical impedance spectroscopy (EIS). This uniform electropolymerised film was crystallisable and showed a high electrocatalytic ability towards the oxidation of caffeine. To avoid the interferences of the anions, Nafion was covered on the surface of poly(safranine T) film modified glassy carbon electrode. As a new voltammetric sensor, this modified electrode is sensitive, selective and stable to determine caffeine content in tea. The peak current increased linearly with the concentration of caffeine in the range of 3×10(-7)-1×10(-4)M, with a detection limit of 1×10(-7)M. All of these make it a useful tool for determining caffeine content in tea. Whats more, it produces much less organic waste compared with other analytical techniques.

Langmuir-Blodgett film of p-tert-butylthiacalix[4]arene modified glassy carbon electrode as voltammetric sensor for the determination of Hg(II).

The pi-A isotherms and UV-vis spectra of the transferred films suggested that the monolayer of p-tert-butylthiacalix[4]arene can coordinate with Hg(2+) at the air-water surface. From these observations, a glassy carbon electrode coated with Langmuir-Blodgett film of p-tert-butylthiacalix[4] arene as a new voltammetric sensor is designed for the determination of trace amounts of Hg(2+). Compared with bare glassy carbon electrode and modified glassy carbon electrode using direct coating method, the Langmuir-Blodgett film-modified electrode can greatly improve the measuring sensitivity of Hg(2+). Under the selected conditions, the Langmuir-Blodgett film-modified electrode in 0.1molL(-1) H(2)SO(4)+0.01molL(-1) KCl solution shows a linear voltammetric response for Hg(2+) in the range of 5.0x10(-10) to 1.5x10(-7)molL(-1), with a detection limit of 2.0x10(-10)molL(-1). The proposed method was also applied to determine Hg(2+) in water samples (tap, lake and river water). In addition, the fabricated electrode exhibited a distinct advantage of simple preparation, non-toxicity, good reproducibility and good stability.

A supersensitive sensor for rutin detection based on multi-walled carbon nanotubes and gold nanoparticles modified carbon paste electrodes

A new voltammetric sensor was designed by covering a layer of gold nanoparticles (AuNPs) on a carbon paste electrode that was pre-mixed in some multi-walled carbon nanotubes (MWCNT). This sensor exhibited super sensitive detection of the electroactive flavonoid rutin due to the large surface area and good conductivity of MWCNT and AuNPs. Cyclic voltammetry curves at various scan rates and pH were recorded to investigate the redox properties of rutin. Further experiments demonstrated that the oxidative peaks increased linearly with rutin concentrations in the ranges of 4.0 × 10−10 to 1.0 × 10−8 mol L−1 and 2.0 × 10−8 to 1.0 × 10−6 mol L−1 with a limit of detection of 4.0 × 10−11 mol L−1. The method was successfully applied to detect rutin in medicine tablets with satisfactory results.

Sensitive voltammetric determination of baicalein at DNA Langmuir–Blodgett film modified glassy carbon electrode

The present paper describes to modify a double stranded DNA-octadecylamine (ODA) Langmuir-Blodgett film on a glassy carbon electrode (GCE) surface to develop a voltammetric sensor for the detection of trace amounts of baicalein. The electrode was characterized by atomic force microscopy (AFM) and cyclic voltammetry (CV). Electrochemical behaviour of baicalein at the modified electrode had been investigated in pH 2.87 Britton-Robinson buffer solutions by CV and square wave voltammetry (SWV). Compared with bare GCE, the electrode presented an electrocatalytic redox for baicalein. Under the optimum conditions, the modified electrode showed a linear voltammetric response for the baicalein within a concentration range of 1.0 × 10(-8)-2.0 × 10(-6) mol L(-1), and a value of 6.0 × 10(-9) mol L(-1) was calculated for the detection limit. And the modified electrode exhibited an excellent immunity from epinephrine, dopamine, glucose and ascorbic acid interference. The method was also applied successfully to detect baicalein in the medicinal tablets and spiked human blood serum samples with satisfactory results.

Voltammetric Determination of Methylparaban in Cosmetics Using a Multi-Wall Carbon Nanotubes/Nafion Composite Modified Glassy Carbon Electrode

A novel voltammetric sensor using multi-wall carbon nanotubes (MWNTs) coupled with Nafion modified glassy carbon electrode (GCE) was developed for the detection of methylparaben (MP). The sensor exhibited good electrocatalytic activity toward the oxidation of MP in the phosphate buffer solution (PBS, pH 6.5). It displayed good sensitivity, repeatability, reproducibility, and long-term stability. Under the optimized conditions, the anodic peak current was linear with the concentration of MP in the range of 3 × 10−6 mol L−1 to 1 × 10−4 mol L−1. The detection limit was 1 × 10−6 mol L−1. The proposed method was successfully applied to determine MP in cosmetics with satisfactory results.

A novel self-assembly voltammetric sensor for malachite green based on ethylenediamine and graphene oxide

A novel self-assembly modified carbon paste electrode based on ethylenediamine and graphene oxide was proposed as a highly sensitive electrochemical sensor for detection of malachite green. The manufacturing operation of the recommended sensor was characterized by cyclic voltammetry and electrochemical impedance spectroscopy. The electrochemical response of malachite green at this sensor was investigated in detail and a new electroanalytical method was erected with high sensitivity and selectivity. The proposed method exhibited good linearity for malachite green over the range from 8.0 × 10−9 mol L−1 to 8.0 × 10−7 mol L−1 with the detection limit of 5 × 10−9 mol L−1 (S/N = 3) by differential pulse voltammetry under optimum conditions. Finally, the practical application was proven by spiking malachite green standards in lake water with recoveries ranging from 98.80% to 101.10%, showing a satisfactory result.

An adaptive wavelength interval selection by modified particle swarm optimization algorithm: simultaneous spectral or differential pulse voltammetric determination of multiple components with overlapping peaks

The elimination of wavelengths which contain useless or irrelevant information for calibration model is becoming one of the key steps in multicomponent spectral analysis even in situations where the partial least-squares (PLS) regression is applied. Because of the continuity of most kinds of spectral responses, the adaptive wavelength interval selection by modified particle swarm optimization (PSO) could be proposed in the present study. The proposed method was used for simultaneous spectrophotometric determination of caffeine, aspirin, and phenacetin and simultaneous differential pulse voltammetric determination of nitrophenol isomers. The method was eventually applied to commercial drugs. For comparison, a conventional full-spectrum PSO analysis was also performed. Experimental results demonstrate that the adaptive wavelength interval selection by modified PSO is capable of improving the future predictive ability of the model.

Anodic stripping voltammetric determination of silver(I) in water using a 4-tert-butyl-1(ethoxycarbonylmethoxy)thiacalix[4]arene modified glassy carbon electrode

A glassy carbon electrode coated with film of 4-tert-butyl-1-(ethoxycarbonylmethoxy)thiacalix[4]arene is designed for the determination of trace amounts of Ag+. Compared with bare glassy carbon electrode, the modified electrode can greatly improve the measuring sensitivity for Ag+. Under the optimum experimental conditions, the modified electrode in B-R buffer solution (pH 4.5) shows a linear voltammetric response in the range of 5.0 × 10−8–3.0 × 10−6 M with detection limit 1.0 × 10−8 M for Ag+. The high sensitivity, selectivity, and stability of modified electrode also demonstrate its practical application for a simple, rapid and economical determination of Ag+ in water samples.

Combination of methotrexate and emodin interacting with DNA.

Abstract The study on interaction of dsDNA with the combination of methotrexate and emodin demonstrated that emodin and methotrexate can form intermolecular hydrogen bonds that enhance the anticancer effect of methotrexate and decrease the side effects. The results show that a combination of synthetic and herbal medicines in treating cancer is very effective and can be used to select other effective combination uses of antitumor drugs. At the same time, according to different interaction models of methotrexate with dsDNA and ssDNA, methotrexate can be used to discriminate between dsDNA and ssDNA in a DNA biosensor as hybridization indicator.