Tin oxide nanoparticles-polymer modified single-use sensors for electrochemical monitoring of label-free DNA hybridization.
ABSTRACT In this study, SnO(2) nanoparticles (SNPs)-poly(vinylferrocenium) (PVF(+)) modified single-use graphite electrodes were developed for electrochemical monitoring of DNA hybridization. The surfaces of polymer modified and polymer-SNP modified pencil graphite electrodes (PGEs) were firstly characterized by using SEM analysis. The electrochemical behaviours of these electrodes were also investigated using the differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS) techniques. The polymer-SNP modified PGEs were then tested for the electrochemical sensing of DNA based on the changes at the guanine oxidation signals. Experimental parameters, such as; different modifications in DNA oligonucleotides, DNA probe concentrations were examined to obtain more sensitive and selective electrochemical signals for nucleic acid hybridization. After optimization studies, DNA hybridization was investigated in the case of complementary of hepatitis B virus (HBV) probe, mismatch (MM), and noncomplementary (NC) sequences.
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ABSTRACT: A novel gold nanoparticle-modified graphite pencil electrode (AuNP-GPE) is prepared just by immersing a bare GPE in AuNP solution, followed by heating for 15 min. The bare and modified GPEs are characterized by FE-SEM imaging and cyclic voltammetry. The AuNP-GPEs showed excellent electrocatalytic activities with respect to hydrazine oxidation, with good reproducibility. To reduce the quantification and detection limits, and increase the hydrazine sensitivity, the pH and square wave voltammetry parameters are optimized. A square wave voltammetry study as a function of the hydrazine concentration showed that the AuNP-GPE detector's quantification limit was 100 nmol L−1 hydrazine, much lower than the value obtained using amperometry (10 µmol L−1). The limits of detection (at 3σ) for hydrazine sensing at AuNP-GPEs using square wave voltammetry and amperometry were 42 nmol L−1 and 3.07 µmol L−1. Finally, the modified electrode was used to determine the hydrazine concentration in drinking water, and satisfactory results are obtained. This simple, rapid, low-cost method for fabricating a modified electrode is an attractive approach to the development of new sensors.Talanta 10/2013; 115:214–221. · 3.50 Impact Factor
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ABSTRACT: In this paper we critically review detection limits of electrochemical DNA biosensors enabling DNA detection without target labelling. The review includes transduction principles and latest breakthroughs. To compare the efficiency of each type of electrochemical DNA biosensor, a simple DNA biosensors classification is established on the basis of the nature of the bio-electrochemical transduction.Analytical and Bioanalytical Chemistry 01/2013; · 3.66 Impact Factor
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ABSTRACT: A sensitive electrochemical impedimetric DNA biosensor based on the integration of tin oxide (SnO2) nanoparticles, chitosan (CHIT) and multi-walled carbon nanotubes (MWNTs) is presented in this paper. The MWNTs-SnO2-CHIT composite modified gold electrode was characterized by cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). Compared with individual MWNTs-CHIT, SnO2-CHIT and bare gold electrode, this composite showed the most obvious electrochemical signal of the redox probe [Fe(CN)6](3-/4-). According to the change of the electron transfer resistance (Ret) induced by the hybridization, target DNA was successfully detected via EIS. This DNA electrochemical biosensor was applied to detect phosphinothricin acetyltransferase (PAT) gene in transgenic corn. The synergistic effect of the MWNTs-SnO2-CHIT remarkably enhanced DNA immobilization and hybridization detection. The dynamic detection range was from 1.0×10(-11)mol/L to 1.0×10(-6)mol/L with a detection limit of 2.5×10(-12)mol/L. This sensing platform showed inner advantage, such as simplicity, good stability, and high sensitivity.Colloids and surfaces B: Biointerfaces 01/2013; · 4.28 Impact Factor