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ABSTRACT: The effect of the SnO(2) nanoparticles (SNPs) on the behaviour of voltammetric carbon paste electrodes were studied for possible use of this material in biosensor development. The electrochemical behaviour of SNP modified carbon paste electrodes (CPE) was first investigated by using cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. The performance of the SNP modified electrodes were compared to those of unmodified ones and the parameters affecting the response of the modified electrode were optimized. The SNP modified electrodes were then tested for the electrochemical sensing of DNA purine base adenine to explore their further development in biosensor applications.
Colloids and surfaces. B, Biointerfaces 08/2011; 86(1):154-7. · 2.60 Impact Factor
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ABSTRACT: The development of amino-terminated G4 PAMAM dendrimer (PDR) modified disposable electrodes were developed as the first time in our study by using the dendrimer modified disposable graphite (PDR-PGE) and multiwalled carbon nanotube based screen-printed graphite (PDR-MWCNT-SPE) electrodes. Firstly, the microscopic characterization of bare PGEs and PDR modified PGEs was performed. These sensors were then applied for electrochemical monitoring of an anticancer drug, Daunorubicin (DNR). The enhanced oxidation signal of DNR was measured at +0.50 V by using differential pulse voltammetry (DPV) in combination with the PDR-PGEs. The detection limit, estimated from S/N = 3, corresponds accordingly to 317 nM and 128 nM for DNR respectively at the PGE and PDR-PGE. The voltammetric results were consistent with electrochemical impedance spectroscopy (EIS) that was used to characterize the successful modification of PDR onto the surface of PGE and MWCNT-SPE.
The Analyst 03/2011; 136(5):1041-5. · 4.23 Impact Factor
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ABSTRACT: The electrochemical aspects of interactions between DNA and two organic compounds are discussed herein. Potential DNA targeted compounds, 2-methyl-4-phenyl-benzo[4,5]imidazo[1,2-a]pyrimidine (C1) and 2,3,4-trimethyl-benzo[4,5]imidazo[1,2-a]pyrimidine (C2), were synthesized and their cytotoxic and/or growth inhibitory effects were studied previously. Disposable sensor technology was used to explore the interaction between the compounds and nucleic acid, such as fish sperm DNA at the electrode surface and in the solution phase. The changes upon encountering oxidation signals of electroactive DNA base-guanine and these compounds were monitored electrochemically.
Analytical Sciences 01/2010; 26(1):117-20. · 1.25 Impact Factor
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ABSTRACT: The interaction of 4-nonylphenol (NP) with deoxyribonucleic acid (DNA) was explored electrochemically by using differential pulse voltammetry (DPV) in combination with unmodified and modified pencil graphite electrodes (PGE) with single walled carbon nanotubes (SWCNT). The differentiation of the two oxidation signals coming from NP and DNA base, guanine was studied before and after the interaction process. In addition, the effect of NP concentration was investigated in order to determine the optimum experimental conditions. The detection limit and the reproducibility were determined by using CNT-modified electrodes.
Analytical Sciences 01/2010; 26(10):1065-9. · 1.25 Impact Factor
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ABSTRACT: A possible DNA damage after interaction of kainic acid (KA) with calf thymus double stranded DNA and genomic DNA was herein determined in in vitro and in vivo conditions using; electrochemical assay and agarose gel electrophoresis. The changes in guanine signal were detected as an indicator of DNA damage in genomic DNA samples isolated from 1 or 10 mg/kg KA-treated animals. The decreased levels of guanine signal were found as 29% and 33% by 1 and 10 mg/kg KA treatment when compared to controls, respectively. The results of gel electrophoresis confirmed DNA damage obtained in identical samples by electrochemical method.
Electroanalysis 10/2009; 21(22):2468 - 2476. · 2.87 Impact Factor
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ABSTRACT: Carboxylic acid functionalized single-walled carbon nanotubes modified graphite sensors (SWCNT-PGEs) were developed for electrochemical monitoring of direct DNA hybridization related to specific sequence of Hepatitis B virus, which substantially enhance the electrochemical transduction resulting from guanine oxidation signal comparison to bare PGEs. The performance characteristics of DNA hybridization on disposable CNT-PGE were explored measuring the guanine signal in terms of optimum analytical conditions; probe and target concentration, hybridization time, and selectivity. The voltammetric results were also complemented with electrochemical impedance spectroscopy (EIS), that was used to characterize the successful construction of carbon nanotubes modification onto the surface of PGEs.
Electroanalysis 08/2009; 21(19):2116 - 2124. · 2.87 Impact Factor
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ABSTRACT: A magnetic particle assay has been designed herein that can report the interactions of DNA aptamers with their cognate protein targets lysozyme (LYS) and human thrombin (THR). Electrochemical sensing of the biomolecular recognition between each aptamer and its target was explored by using a disposable graphite electrode, PGE, in combination with differential pulse voltammetry (DPV). The magnitudes of the oxidation signals of LYS and THR were measured at +780 mV and +680 mV, respectively, after interaction with the cognate aptamers attached to the surface of magnetic particles. The detection limits estimated for signal to noise ratios above 3.0 correspond to the concentrations of 10.77 μg/mL LYS (769 nM) and 2.00 μg/mL THR (54.5 nM). Our aptamer based approach that combines magnetic particles with a disposable graphite electrode performs well compared to other aptamer-based sensor-formats for quantitative protein detection with respect to sensitivity, selectivity, detection limit, and reproducibility.
Electroanalysis 05/2009; 21(11):1278 - 1284. · 2.87 Impact Factor
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ABSTRACT: Single-walled carbon nanotubes (SWCNT) modified disposable graphite electrodes (SWCNT-PGEs) were investigated in our study for the improved electrochemical monitoring of nucleic acids and biomolecular interactions based on the higher signal enhancement comparison to bare PGEs. The surface morphologies of bare PGE and SWCNT-PGE were firstly explored using scanning electron microscopy (SEM) analysis. The easy surface modification of disposable graphite electrodes with carbon nanotubes was performed by passive adsorption, and DNA was then immobilized onto the SWCNT-PGEs by the formation of covalent coupling between the carboxylated ends of nanotubes and the amine group in the guanine bases of DNA. The overall performance of SWCNT-PGEs has also been studied, and discussed in terms of optimum analytical conditions; such as, the effect of pretreatment step, CNT concentration, DNA concentration, etc. The reproducible detection of DNA represent a very attractive approach for the further detection of interaction between the anticancer drug, daunorubicin (DNR) and double stranded DNA (dsDNA). Voltammetric results were complemented with electrochemical impedance spectroscopy (EIS), that was used to characterize the successful construction of carbon nanotubes modification onto the surface of PGEs.
Electroanalysis 01/2009; 21(3‐5):464 - 471. · 2.87 Impact Factor
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ABSTRACT: The application of multiwalled carbon nanotube (MWCNT) based screen printed graphite electrodes (SPEs) was explored in this study for the electrochemical monitoring of DNA hybridization related to specific sequences on Hepatitis B virus (HBV) DNA. After the microscopic characterization of bare MWCNT-SPEs and DNA immobilized ones was performed, the optimization of assay has been studied. The development of screen printing process combined with nanomaterial based disposable sensor technology leads herein a great opportunity for DNA detection using differential pulse voltammetry (DPV) by measuring the guanine oxidation signal observed at +1.00 V in the presence of DNA hybridization between HBV probe and its complementary, target. The detection limit estimated for signal to noise ratios =3 corresponds to 96.33 nM target concentration in the 40 μL samples. The advantages of carbon nanotube based screen printed electrode used for electrochemical monitoring of DNA hybridization are discussed with sensitivity, selectivity and reproducibility in comparison with previous nanomaterial based electrochemical transducers developed for DNA or other biomolecular recognitions.
Electroanalysis 07/2008; 20(17):1932 - 1938. · 2.87 Impact Factor
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ABSTRACT: An electrochemical approach for the improved electrochemical sensing of DNA was developed in this study based on the oxidation signals of silver and DNA base, guanine by using disposable pencil graphite electrode (PGE) electrodes. The easy surface modification of disposable electrodes PGEs with nucleic acids was performed by passive adsorption using amino linked DNA oligonucleotide attached onto the surface of silver nanoparticles (Ag-NPs). Firstly, the microscopic characterization of silver nanoparticles was investigated by transmission electron microscopy (TEM) and scanning electron microscopy (SEM), and the electrochemical behaviour of these NPs was studied by using cyclic voltammetry (CV) and differential pulse voltammetry (DPV) techniques. Then, the overall performance of this novel electrochemical DNA sensing method based on these nanoparticles is studied and discussed in terms of optimum analytical conditions, such as; the effect of DNA concentration, NPs concentration and different buffer solutions, etc. in order to obtain silver and guanine oxidation signals in higher sensitivity and selectivity. The main features related with this electrochemical assay based on silver nanoparticles are discussed and compared with other assays reported in the literatures.
Electrochemistry Communications 9(9):2167-2173. · 4.86 Impact Factor
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ABSTRACT: The biomolecular interactions of platinum derivatives widely used as anticancer drugs: cis-diamminedichloroplatinum(II) and oxaliplatin with calf thymus double-stranded DNA were studied using differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) in combination with single-walled carbon nanotubes modified graphite electrode (SWCNTs-GE) and unmodified graphite electrode (bare GE). The performance of these biomolecular interactions were explored at the electrode surface by monitoring the changes at guanine oxidation signal in terms of optimum interaction times by comparing the results of SWCNTs-GE with bare one. The features of these electrochemical sensors based on carbon nanotubes for monitoring of biomolecular interactions were discussed and compared with the earlier conventional ones.
Materials Science and Engineering: B.
