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Damietta, Egypt

Radi A.-E.,Dumyat University | Abd-Elaziz I.,Dumyat University
Analytical Methods | Year: 2015

In this work, a novel and selective polypyrrole (PPy) electropolymerized molecularly imprinted electrochemical sensor (PPy-MIP) for halofuginone (HFG) determination was developed. The imprinted film was fabricated by electropolymerization of pyrrole (Py) in the presence of halofuginone (HFG) onto a glassy carbon electrode (GCE) surface. The electrochemical sensor exhibits a remarkable sensitivity, which might be due to the plenty of cavities for binding HFG through π-π stacking between aromatic rings and hydrogen bonds between nitrogen and oxygen-containing groups of HFG and PPy. Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) were employed to characterize the constructed sensor. The effects of pH, the monomer concentration, the number of cycles for the electropolymerization, and the scan rate for the sensor preparation were optimized. Under the optimal conditions, the DPV peak current was linear to the HFG concentration in the range from 7.5 × 10-9 to 1.0 × 10-5 M, with a detection limit of 2.5 × 10-9 M. The prepared sensor also showed acceptable storage stability, reproducibility and regeneration capacity. The electrochemical sensor was applied to determine HFG in chicken meat samples with satisfactory results. © 2015 The Royal Society of Chemistry. Source

Radi A.-E.,Dumyat University | Khafagy A.,Dumyat University | El-Shobaky A.,Dumyat University | El-Mezayen H.,Helwan University
Journal of Pharmaceutical Analysis | Year: 2013

The electrochemical oxidation behavior and voltammetric assay of gemifloxacin were investigated using differential-pulse and cyclic voltammetry on a screen-printed carbon electrode. The effects of pH, scan rates, and concentration of the drug on the anodic peak current were studied. Voltammograms of gemifloxacin in Tris-HCl buffer (pH 7.0) exhibited a well-defined single oxidation peak. A differential-pulse voltammetric procedure for the quantitation of gemifloxacin has been developed and suitably validated with respect to linearity, limits of detection and quantification, accuracy, precision, specificity, and robustness. The calibration was linear from 0.5 to 10.0 μM, and the limits of detection and quantification were 0.15 and 5.0 μM. Recoveries ranging from 96.26% to 103.64% were obtained. The method was successfully applied to the determination of gemifloxacin in pharmaceutical tablets without any pre-treatment. Excipients present in the tablets did not interfere in the assay. © 2013 Xi'an Jiaotong University. Production and hosting by Elsevier B.V. All rights reserved. Source

Radi A.-E.,Dumyat University | El-Naggar A.-E.,Dumyat University | Nassef H.M.,Dumyat University
Electrochimica Acta | Year: 2014

The interaction of the antiparasitic drug nitazoxanide (NTZ) with salmon sperm double strand deoxyribonucleic acid (ss-ds-DNA) has been studied using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) at screen printed carbon electrode (SPCE). NTZ shows two irreversible oxidation peaks measured in 0.02 M phosphate buffer (pH 4.0 and 7.4). UV/Vis spectroscopy was also employed to probe the interaction between NTZ and ss-ds-DNA. From the CV data, the diffusion coefficients were found as 5.1 × 10-7 and 4.9 × 10-9 cm2s-1 for NTZ and NTZ-DNA, respectively. Based on the CV and spectroscopic results, the binding constant between NTZ and DNA was calculated to be 4.1 × 105 M -1 and 5.0 × 105 M-1, respectively. The interaction as a sum of intercalation and groove binding modes was concluded. A procedure for the differential pulse voltammetric determination of NTZ at a screen-printed electrode surface modified with the ss-ds-DNA layer was also described. The method was applied for the determination of NTZ in spiked serum. © 2014 Elsevier Ltd. Source

Radi A.-E.,Dumyat University | Nassef H.M.,Dumyat University | Eissa A.,Dumyat University
Electrochimica Acta | Year: 2013

The interaction of anticancer drug etoposide (ETO) with salmon sperm double strand deoxyribonucleic acid (ss dsDNA) in aqueous solution and immobilized on a screen-printed carbon electrode (SPCE) has been thoroughly explored using voltammetric techniques. UV-vis absorption spectroscopic technique was also employed to probe the interaction between the ETO and ss dsDNA in solution. ETO showed two oxidation peaks in phosphate buffer solutions (20 mM, pH 4.5 and 7.4). The changes in the anodic current signals of ETO were monitored in the presence and absence of ss dsDNA by using an oxidized bare SPCE in connection with differential pulse voltammetry (DPV) and cyclic voltammetry (CV). The diffusion coefficient for the free ETO was 4.2 × 10-6 cm 2 s-1 and 3.8 × 10-7 cm2 s-1 for the ETO-DNA complex. The electrochemical indicated a 1:1 complex formation of ETO with DNA. The values of binding constant have been determined to be 4.1 × 105 M-1 and 4.8 × 105 M-1; and 5.2 × 105 M-1 and 5.6 × 105 M-1 for ETO and ETO cation free radical in phosphate buffer solutions of pH 4.5 and 7.4; respectively. The overall results suggest that ETO binds to DNA through combined effect of intercalation and electrostatic interaction. A detection scheme based on a preconcentration and DPV determination at ss dsDNA modified SPCEs (DNA/SPCEs) was proposed for the trace determination of the ETO. The developed method was successfully applied to the determination of the ETO in spiked human serum samples. © 2013 Elsevier Ltd. Source

Radi A.-E.,Dumyat University | Nassef H.M.,Dumyat University | Eissa A.,Dumyat University
Electroanalysis | Year: 2013

Damage of salmon sperm double strand ss dsDNA in solution or immobilized on screen-printed carbon electrode (SPCE) induced by incubation of DNA with the antineoplastic alkylating agent busulfan (BUS) at various conditions was detected for the first time by simple electrochemical methods. Chemical changes in DNA bases can be detected through the altered electroactivity of the DNA. Electrochemical voltammetric sensing of damage caused by BUS to dsDNA in solution was monitored by the appearance of peaks diagnostic of the oxidation of guanine and adenine. Moreover, crystal violet, which interacts with the DNA immobilized on SPCEs, was used as an effective electroactive indicator, in combination with cyclic voltammetry and differential pulse voltammetry techniques to monitor the cross-links or damage to DNA. The interaction between BUS and DNA were determined by the changes in the voltammetric peak of crystal violet. The effects of various conditions upon the crystal violet signal were investigated. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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