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Gao H.,Shandong Entry Exit Inspection and Quarantine Bureau of the Peoples Republic of China | Qi X.,Qingdao University of Science and Technology | Chen Y.,Chinese Academy of Inspection and Quarantine | Sun W.,Shandong Entry Exit Inspection and Quarantine Bureau of the Peoples Republic of China
Analytica Chimica Acta | Year: 2011

An electrochemical DNA biosensor was fabricated by self-assembling probe single-stranded DNA (ssDNA) with a nanogold decorated on ionic liquid modified carbon paste electrode (IL-CPE). IL-CPE was fabricated using 1-butylpyridinium hexafluorophosphate as the binder and the gold nanoparticles were electrodeposited on the surface of IL-CPE (Au/IL-CPE). Then mercaptoacetic acid was self-assembled on the Au/IL-CPE to obtain a layer of modified film, and the ssDNA probe was further covalently-linked with mercaptoacetic acid by the formation of carboxylate ester with the help of N-(3-dimethylamino-propyl)-N'-ethylcarbodiimide hydrochloride and N-hydroxysuccinimide. The hybridization reaction with the target ssDNA was monitored with methylene blue (MB) as the electrochemical indicator. Under the optimal conditions, differential pulse voltammetric responses of MB was proportional to the specific ssDNA arachis sequences in the concentration range from 1.0×10 -11 to 1.0×10 -6molL -1 with the detection limit as 1.5×10 -12molL -1 (3σ). This electrochemical DNA sensor exhibited good stability and selectivity with the discrimination ability of the one-base and three-base mismatched ssDNA sequences. The polymerase chain reaction product of arachis Arabinose operon D gene was successfully detected by the proposed method, which indicated that the electrochemical DNA sensor designed in this paper could be further used for the detection of specific ssDNA sequence. © 2011 Elsevier B.V. Source


Sun W.,Hainan Normal University | Sun W.,Qingdao University of Science and Technology | Qi X.,Qingdao University of Science and Technology | Zhang Y.,Qingdao University of Science and Technology | And 4 more authors.
Electrochimica Acta | Year: 2012

A new electrochemical DNA biosensor was fabricated by using a dendritic gold nanoparticles and electrochemical reduced graphene (GR) composite modified carbon ionic liquid electrode (CILE) as the platform. Ionic liquid 1-butylpyridinium hexafluorophosphate was used as the binder for the preparation of CILE and GR film was further decorated on the CILE surface by electrochemical reduction. Then the dendritic nanogold was electrodeposited on the surface of GR/CILE to get a modified electrode as Au/GR/CILE, which was further used for the formation of mercaptoacetic acid self-assembling film. The amino modified ssDNA probe sequence was covalently linked with mercaptoacetic acid to get the ssDNA modified electrode for the further hybridization. Methylene blue (MB) was used as the electrochemical indicator for monitoring the hybridization reaction after hybridized with the target ssDNA. Under the optimal conditions the specific Listeria monocytogenes hly ssDNA sequences could be detected by measuring the differential pulse voltammetric responses of the accumulated MB molecules on dsDNA molecules. The linear concentration range was achieved from 1.0 × 10-12 to 1.0 × 10-6 mol/L with the detection limit as 2.9 × 10-13 mol/L (3σ). This electrochemical DNA sensor exhibited excellent selectivity with the good discrimination ability of one-base and three-base mismatched ssDNA sequences. The polymerase chain reaction product of L. monocytogenes hly gene that extracted from deteriorated fish was successfully detected, which indicated that this electrochemical DNA sensor could be further used for the detection of specific ssDNA sequence in real biological samples. © 2012 Elsevier Ltd. Source


Sun W.,Qingdao University of Science and Technology | Qi X.,Qingdao University of Science and Technology | Chen Y.,Chinese Academy of Inspection and Quarantine | Liu S.,Qingdao University of Science and Technology | Gao H.,Shandong Entry Exit Inspection and Quarantine Bureau of the Peoples Republic of China
Talanta | Year: 2011

In this paper a Fe 3O 4 microsphere, graphene (GR) and chitosan (CTS) nanocomposite material modified carbon ionic liquid electrode (CILE) was used as the platform for the construction of a new electrochemical DNA biosensor. The single-stranded DNA (ssDNA) probe was immobilized directly on the surface of the CTS/Fe 3O 4-GR/CILE, which could hybridize with the target ssDNA sequence at the selected conditions. By using methylene blue (MB) as the electrochemical indicator the hybridization reaction was investigated with the reduction peak current measured. By combining the specific properties such as the biocompatibility and big surface area of Fe 3O 4 microspheres, the excellent electron transfer ability of GR, the good film-forming ability of CTS and the high conductivity of CILE, the synergistic effects of nanocomposite increased the amounts of ssDNA adsorbed on the electrode surface and then resulted in the greatly increase of the electrochemical responses. Under the optimal conditions differential pulse voltammetric responses of MB were proportional to the specific ssDNA sequences concentration in the range from 1.0 × 10 -12 to 1.0 × 10 -6 mol/L with the detection limit as 3.59 × 10 -13 mol/L (3σ). This DNA biosensor showed good stability and discrimination ability to one-base and three-base mismatched ssDNA sequences. The polymerase chain reaction (PCR) product of soybean Lectin gene sequence was detected by the proposed method with satisfactory result, suggesting that the CTS/Fe 3O 4-GR/CILE was a suitable sensing platform for the sensitive detection of specific gene sequence. © 2011 Elsevier B.V. All rights reserved. Source


Sun W.,Hainan Normal University | Zhang Y.,Qingdao University of Science and Technology | Ju X.,Qingdao University of Science and Technology | Li G.,Qingdao University of Science and Technology | And 2 more authors.
Analytica Chimica Acta | Year: 2012

A carboxyl functionalized graphene oxide (GO-COOH) and electropolymerized ploy-l-lysine (PLLy) modified glassy carbon electrode (GCE) was fabricated and used for the construction of an electrochemical deoxyribonucleic acid (DNA) biosensor. The NH2 modified probe ssDNA sequences were immobilized on the surface of GO-COOH/PLLy/GCE by covalent linking with the formation of amide bonds, which was stable and furthur hybridized with the target ssDNA sequence. Differential pulse voltammetry (DPV) was used to monitor the hybridization events with methylene blue as electrochemical indicator, which gave a sensitive reduction peak at -0.287V (vs. SCE). Under the optimal conditions the reduction peak current was proportional to the concentration of tlh gene sequence in the range from 1.0×10-12 to 1.0×10-6molL-1 with a detection limit as 1.69×10-13molL-1 (3σ). The polymerase chain reaction products of tlh gene from oyster samples were detected with satisfactory results, indicating the potential application of this electrochemical DNA sensor. © 2012 Elsevier B.V. Source


Gao H.,Shandong Entry Exit Inspection and Quarantine Bureau of the Peoples Republic of China | Sun M.,Shandong Entry Exit Inspection and Quarantine Bureau of the Peoples Republic of China | Lin C.,Shandong Entry Exit Inspection and Quarantine Bureau of the Peoples Republic of China | Wang S.,Qingdao Agricultural University
Electroanalysis | Year: 2012

Based on graphene (GR), TiO2 nanorods, and chitosan (CTS) nanocomposite modified carbon ionic liquid electrode (CILE) as substrate electrode, a new electrochemical DNA biosensor was effectively fabricated for the detection of the transgenic soybean sequence of MON89788. By using methylene blue (MB) as hybridization indicator for monitoring the hybridization with different ssDNA sequences, the differential pulse voltammetric response of MB on DNA modified electrodes were recorded and compared. Due to the synergistic effects of TiO2 nanorods and GR on the electrode surface, the electrochemical responses of MB were greatly increased. Under optimal conditions the differential pulse voltammetric response of the target ssDNA sequence could be detected in the range from 1.0×10-12 to 1.0×10-6mol/L with a detection limit of 7.21×10-13mol/L (3σ). This electrochemical DNA biosensor was further applied to the polymerase chain reaction (PCR) product of transgenic soybeans with satisfactory results. © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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