Chitosan Modified Carbon Paste Electrode Research Articles

A voltammetry sensor platform for baicalein and baicalin simultaneous detection in vivo based on Ta2O5-Nb2O5@CTS composite

Baicalein and baicalin are the major flavonoids found in Scutellariae Radix, an essential herb which has had a presence in traditional Chinese medicine (TCMs) for more than two thousands of years. Owing to their similar characteristics and physiochemical properties, sensitive, it is a great challenge to detect both of them simultaneously. In this work, a novel, facile and sensitive electrochemical method was proposed based on tantalum oxide (Ta2O5), niobium oxide (Nb2O5) particles and antiseptic chitosan modified carbon paste electrode (Ta2O5-Nb2O5@CTS-CPE). Scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectrum (EIS) were used to characterize the properties and investigate the electrochemical response of the sensor. The electrochemical behaviors and redox mechanisms of two analytes were investigated at the target electrode. Under the optimum conditions, the highly sensitive and simultaneous determination of baicalein and baicalin was successfully achieved with a linear response range of 0.08–8.0μM for both of them. The obtained detection limits for baicalein and baicalin were of 0.05 and 0.03μM (S/N=3), respectively. Furthermore, the proposed sensor displayed high sensitivity, excellent stability and satisfactory results in Scutellariae Radix samples analysis and hydrolysis process analysis of baicalin in vivo.

Sensitive, simultaneous determination of chrysin and baicalein based on Ta2O5-chitosan composite modified carbon paste electrode

Chrysin and baicalein are the major flavonoids found in oroxylum indicum, an essential herb in traditional Chinese medicine (TCM). Owing to their similar characteristics and physiochemical property, it is a great challenge to detect both of them simultaneously. In this work, tantalum oxide (Ta2O5) particles and chitosan modified carbon paste electrode (Ta2O5-CTS-CPE) was prepared and characterized by scanning electron microscope (SEM), X-ray diffraction spectroscopy (XRD), Fourier transform infrared spectroscopy (FTIR), cyclic voltammetry (CV) and electrochemical impedance spectrum(EIS). Under the optimum conditions, the prepared Ta2O5-CTS-CPE exhibited excellent electrocatalytic activity toward the oxidation of chrysin and baicalein, and it could serve as the sensor for highly sensitive and simultaneous determination both of them. The linear range is 0.08–4.0μM for both of them, and the detection limits were determined to be 0.03 and 0.05μM (S/N=3) for chrysin and baicalein, respectively. Furthermore, the proposed electrochemical sensor displayed high sensitivity, excellent stability and got satisfactory results in oroxylum indicum samples analysis.

Mercury Nanodroplets Immobilized on the Surface of a Chitosan-Modified Carbon Paste Electrode as a New Thallium Sensor in Aqueous Samples

In the present work chitosan (CT) was used to construct a chitosan-modified carbon paste electrode (CT/CPE). The amine groups in the chitosan bind mercury ions from an aqueous KCl solution (PH 5.0). Then the electrode was held at a negative potential (−1.3 V) to reduce the Hg2+ bound to the CT/CPE to forming mercury nanodroplets. The proposed electrode was evaluated for preconcentration and determination of Tl+1 ions by differential pulse anodic stripping voltammetry (DPASV). The electrochemical procedure was based on the accumulation of thallium ions at the surface of the modified carbon paste electrode with mercury nanodroplets and chitosan biopolymer. Parameters involved in the binding of Hg+2 ions to the CT/MCPE, preconcentration of thallium ions and voltammetric stripping step were studied and the best set of experimental conditions were chosen. Under the optimized conditions, the voltammetric peak current of Tl+1 increased linearly with Tl+1 concentrations in the range of 1.0–400 ng mL−1 and a detection limit of 0.20 ng mL−1 was obtained for Tl+1. The practical application of the suggested modified electrode was evaluated by the determination of trace amount of Tl in the environmental and biological samples.

Square wave voltammetric determination of paracetamol at chitosan modified carbon paste electrode: Application in natural water samples, commercial tablets and human urines.

A novel analytical approach has been developed and evaluated for the quantitative analysis of paracetamol (PCT). The anodic peak currents of paracetamol on the CS-CPE were about 200 fold higher than that of the unmodified electrodes. The influence of various parameters on the CS-CPE was investigated. Under the optimized working conditions, the oxidation peak current is linear to the paracetamol concentration in the ranges of 1.0 × 10(-3)-4.0 × 10(-4)mol L(-1) and 2.0 × 10(-4)-8.0 × 10(-7)mol L(-1) with a detection limit of 5.08 × 10(-7)mol L(-1). The repeatability of the method expressed as relative standard deviation (RSD) is 1.73% (n=8). Possible interferences were tested and evaluated in 1.0 × 10(-4)mol L(-1) paracetamol in the presence of inorganic ions, dopamine, ibuprofen, ascorbic acid and uric acid. The proposed method was successfully applied to PCT determination in natural waters, tablets and urine samples.

A novel, effective and low cost catalyst for formaldehyde electrooxidation based on nickel ions dispersed onto chitosan-modified carbon paste electrode for fuel cell

In this study, a novel modified carbon paste electrode (CPE) was fabricated by chitosan and then Ni2+ ions incorporated to this electrode by immersion of the modified electrode in a 0.5 M nickel chloride solution. The values of charge-transfer rate constant and electrode surface coverage for Ni(II)/Ni(III) redox couple and redox sites of modified carbon paste electrode (Ni-CHIT/CPE) were found to be 0.174 s−1 and 7.38 × 10−8 mol cm−2, respectively. The electrochemical behavior of the Ni-CHIT/CPE electrode towards oxidation of formaldehyde was evaluated by cyclic voltammetry technique as well as chronoamperometry method. It has been observed that chitosan at the surface of CPE can improve catalytic efficiency of the dispersed nickel ions toward oxidation of formaldehyde. The values of electron transfer coefficient, diffusion coefficient and the mean value of catalytic rate constant for formaldehyde and redox sites were obtained to be 0.47, 2.68 × 10−6 cm2 s−1 and 2.06 × 105 cm3 mol−1 s−1, respectively. Obtained results from cyclic voltammetry and chronoamperometric techniques specified that the electrode reaction is a diffusion-controlled process. The good catalytic activity, high sensitivity, good stability and easy in preparation rendered the Ni-CHIT/CPE to be a capable electrode for electrooxidation of formaldehyde.

Electrochemical determination of biophenol oleuropein using a simple label-free DNA biosensor

Oleuropein (Ole), naturally occurring phenolic compound found in olive products, is well known for its benefits for human health. In the present work, a simple, sensitive and rapid determination of Ole was achieved using a label-free electrochemical DNA biosensor. The application was related to the molecular interaction between Ole and double-stranded DNA (dsDNA). So, the voltammetric behavior of Ole at the surface of a DNA-immobilized chitosan-modified carbon paste electrode was studied using differential pulse voltammetry (DPV) where the oxidation peak current of Ole was measured as an analytical signal. A considerable increase was observed in the oxidation signal of Ole at the DNA-coated electrode compared with the DNA-free electrode, indicating the pre-concentration of Ole due to the interaction with the surface-confined DNA layer. In order to use the proposed sensor for real samples, different parameters affecting Ole signal such as, immobilization time and potential, accumulation time and pH, and stripping pH were optimized. Under optimized experimental conditions, a linear concentration range of 0.30–12μmolL−1 with a detection limit of 0.090μmolL−1 was obtained for Ole determination. The proposed biosensor was successfully applied to the determination of Ole in olive leaf extract and human serum samples.

The electrochemical oxidation of pentachlorophenol and its sensitive determination at chitosan modified carbon paste electrode

We report on a novel electrochemical method to detect trace pentachlorophenol (PCP) by using a chitosan (CS) modified carbon paste electrode (CS/CPE). Compared with that at a bare carbon paste electrode (CPE), the current response was greatly improved at the CS/CPE due to the enhancement effect of CS. Under optimal working conditions, the oxidation peak current of PCP was proportional to its concentration in the range of 1.0 × 10−7 to 5.0 × 10−6 and 5.0 × 10−6 to 1.0 × 10−4 mol/L, with an extremely low detection limit of 4.0 × 10−8 mol/L. Our method was successfully used to detect the PCP concentration in vegetable samples.

Adsorptive Stripping Voltammetric Determination of Mangiferin Using an Activated Chitosan Modified Carbon Paste Electrode

A medium molecular weight powdered chitosan modified carbon paste electrode was used to investigate the electrochemical behaviour by cyclic voltammetry of the pharmacologically-active ingredient mangiferin (MG). An irreversible system was observed, with a peak at ﹢0.55 V (vs Ag/AgCl). The peak current increases about fourfold, at the modified electrode in comparison with that recorded at the chitosan free carbon paste electrode. This allowed the use of adsorptive stripping voltammetry to develop a simple and sensitive electroanalytical method for the determination of MG. The influence of key parameters was investigated, including the electrolysis potential, the preconcentration time, the pH of supporting electrolyte and MG concentration. Upon optimisation of these parameters, the electrode response was found to be directly proportional to the concentration of MG in the range from 2.06 × 10﹣6 M to 6.74 × 10﹣5 M, leading to a detection limit of 1.84 μM for 240 s preconcentration at ﹣0.1 V. A mechanism was also proposed for the electrochemical oxidation of MG.

Differential Pulse Voltammetric Determination of Montelukast in Tablets and Human Plasma by Using Chitosan Modified Carbon Paste Electrode

AbstractElectrochemical reduction and determination of montelukast (MKS) was studied in methanol – 0.1 M HCl solution (1 : 1, v/v) by cyclic voltammetry (CV) and differential pulse voltammetry (DPV) at chitosan modified carbon paste electrode. The linear range was 1.70×10−7–1.83×10−5 M for DPV analysis. Limit of detection (LOD) and limit of quantification (LOQ) were 5.32×10−8 M and 1.61×10−7 M, respectively. The developed method was successfully applied to the determination of MKS in tablets and spiked human plasma. The results obtained were in good agreement with those obtained using a reported spectrofluorimetric technique.

Electrochemical detection of short sequences related to the hepatitis B virus using MB on chitosan-modified CPE

A novel electrochemical DNA biosensor based on methylene blue (MB) and chitosan-modified carbon paste electrode (CCPE) for short DNA sequences and polymerase chain reaction (PCR) amplified real samples related to the hepatitis B virus (HBV) hybridization detection is presented. Differential pulse voltammetry (DPV) was used to investigate the surface coverage and hybridization event. The decrease in the peak current of MB, an electroactive label, was observed upon hybridization of probe with the target. Numerous factors affecting the target hybridization and indicator binding reaction are optimized to maximize the sensitivity.

Label‐Free and Label Based Electrochemical Detection of Hybridization by Using Methylene Blue and Peptide Nucleic Acid Probes at Chitosan Modified Carbon Paste Electrodes

AbstractA chitosan modified carbon paste electrode (ChiCPE) based DNA biosensor for the recognition of calf thymus double stranded DNA (dsDNA), single stranded DNA (ssDNA) and hybridization detection between complementary DNA oligonucleotides is presented. DNA and oligonucleotides were electrostatically attached by using chitosan onto CPE. The amino groups of chitosan formed a strong complex with the phosphate backbone of DNA. The immobilized probe could selectively hybridize with the target DNA to form hybrid on the CPE surface. The detection of hybridization was observed by using the label‐free and label based protocols. The oxidation signals of guanine and adenine greatly decreased when a hybrid was formed on the ChiCPE surface. The changes in the peak currents of methylene blue (MB), an electroactive label, were observed upon hybridization of probe with target. The signals of MB were investigated at dsDNA modified ChiCPE and ssDNA modified ChiCPE and the increased peak currents were observed, in respect to the order of electrodes. The hybridization of peptide nucleic acid (PNA) probes with the DNA target sequences at ChiCPE was also investigated. Performance characteristics of the sensor were described, along with future prospects.