The Experts below are selected from a list of 6861 Experts worldwide ranked by ideXlab platform
Haesik Yang - One of the best experts on this subject based on the ideXlab platform.
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hydroquinone diphosphate as a phosphatase substrate in enzymatic amplification combined with electrochemical chemical chemical redox cycling for the detection of e coli o157 h7
2013Co-Authors: Md Rajibul Akanda, Myung Ho Hyun, Vellaiappillai Tamilavan, Seonhwa Park, Haesik YangAbstract:Signal amplification by enzyme labels in enzyme-linked immunosorbent assays (ELISAs) is not sufficient for detecting a low number of bacterial pathogens. It is useful to employ approaches that involve multiple signal amplification such as enzymatic amplification plus redox cycling. An advantageous combination of an enzyme product [for fast electrochemical–chemical–chemical (ECC) redox cycling that involves the product] and an enzyme substrate (for slow side reactions and ECC redox cycling that involve the substrate) has been developed to obtain a low detection limit for E. coli O157:H7 in an electrochemical ELISA that employs redox cycling. In our search for an alkaline phosphatase substrate/product couple that is better than the most common couple of 4-aminophenyl phosphate (APP)/4-Aminophenol (AP), we compared five couples: APP/AP, hydroquinone diphosphate (HQDP)/hydroquinone (HQ), l-ascorbic acid 2-phosphate/l-ascorbic acid, 4-amino-1-naphthyl phosphate/4-amino-1-naphthol, and 1-naphthyl phosphate/1-na...
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electrochemical immunosensor using p Aminophenol redox cycling by hydrazine combined with a low background current
2007Co-Authors: Jagotamoy Das, Jae Wook Lee, Haesik YangAbstract:Signal amplification and noise reduction are crucial for obtaining low detection limits in biosensors. Here, we present an electrochemical immunosensor in which the signal amplification is achieved using p-Aminophenol (AP) redox cycling by hydrazine, and the noise level is reduced by implementing a low background current. The redox cycling is obtained in a simple one-electrode, one-enzyme format. In a sandwich-type heterogeneous immunosensor for mouse IgG, an alkaline phosphatase label converts p-aminophenyl phosphate into AP for 10 min. This generated AP is electrooxidized at an indium tin oxide (ITO) electrode modified with a partially ferrocenyl-tethered dendrimer (Fc-D). The oxidized product, p-quinone imine (QI), is reduced back to AP by hydrazine, and then AP is electrooxidized again to QI, resulting in redox cycling. Moreover, hydrazine protects AP from oxidation by air, enabling long incubation times. The small amount of ferrocene in a 0.5% Fc-D-modified ITO electrode, where 0.5% represents the ra...
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A nanocatalyst-based assay for proteins: DNA-free ultrasensitive electrochemical detection using catalytic reduction of p-nitrophenol by gold-nanoparticle labels
2006Co-Authors: Jagotamoy Das, Md Abdul Aziz, Haesik YangAbstract:This communication reports a nanocatalyst-based electrochemical assay for proteins. Ultrasensitive detection has been achieved by signal amplification combined with noise reduction: the signal is amplified both by the catalytic reduction of p-nitrophenol to p-Aminophenol by gold-nanocatalyst labels and by the chemical reduction of p-quinone imine to p-Aminophenol by NaBH4; the noise is reduced by employing an indium tin oxide electrode modified with a ferrocenyl-tethered dendrimer and a hydrophilic immunosensing layer.
Chuanxiang Chen - One of the best experts on this subject based on the ideXlab platform.
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amperometric sensor for hydrogen peroxide based on poly aniline co p Aminophenol
2009Co-Authors: Chuanxiang Chen, Cheng Sun, Yuhua GaoAbstract:Abstract It was found that the poly(aniline- co - p -Aminophenol) film can effectively catalyze the oxidation of hydrogen peroxide in a sodium citrate buffer solution with pH 5.0. Here, we applied the copolymer to the construction of an efficient electrochemical sensor to determine the concentration of hydrogen peroxide. The sensor exhibited an excellent electrocatalytic activity toward the oxidation of H 2 O 2 , and the interferences of ascorbic acid and phenol were completely avoided. Unlike the inherent instability of enzyme, the poly(aniline- co - p -Aminophenol) film-based sensor showed an outstanding stability.
Jagotamoy Das - One of the best experts on this subject based on the ideXlab platform.
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electrochemical immunosensor using p Aminophenol redox cycling by hydrazine combined with a low background current
2007Co-Authors: Jagotamoy Das, Jae Wook Lee, Haesik YangAbstract:Signal amplification and noise reduction are crucial for obtaining low detection limits in biosensors. Here, we present an electrochemical immunosensor in which the signal amplification is achieved using p-Aminophenol (AP) redox cycling by hydrazine, and the noise level is reduced by implementing a low background current. The redox cycling is obtained in a simple one-electrode, one-enzyme format. In a sandwich-type heterogeneous immunosensor for mouse IgG, an alkaline phosphatase label converts p-aminophenyl phosphate into AP for 10 min. This generated AP is electrooxidized at an indium tin oxide (ITO) electrode modified with a partially ferrocenyl-tethered dendrimer (Fc-D). The oxidized product, p-quinone imine (QI), is reduced back to AP by hydrazine, and then AP is electrooxidized again to QI, resulting in redox cycling. Moreover, hydrazine protects AP from oxidation by air, enabling long incubation times. The small amount of ferrocene in a 0.5% Fc-D-modified ITO electrode, where 0.5% represents the ra...
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A nanocatalyst-based assay for proteins: DNA-free ultrasensitive electrochemical detection using catalytic reduction of p-nitrophenol by gold-nanoparticle labels
2006Co-Authors: Jagotamoy Das, Md Abdul Aziz, Haesik YangAbstract:This communication reports a nanocatalyst-based electrochemical assay for proteins. Ultrasensitive detection has been achieved by signal amplification combined with noise reduction: the signal is amplified both by the catalytic reduction of p-nitrophenol to p-Aminophenol by gold-nanocatalyst labels and by the chemical reduction of p-quinone imine to p-Aminophenol by NaBH4; the noise is reduced by employing an indium tin oxide electrode modified with a ferrocenyl-tethered dendrimer and a hydrophilic immunosensing layer.
Shuhua Cheng - One of the best experts on this subject based on the ideXlab platform.
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electrochemically pretreated screen printed carbon electrodes for the simultaneous determination of Aminophenol isomers
2011Co-Authors: Shengming Wang, Shuhua ChengAbstract:Abstract This study reports that disposable, electrochemically pretreated screen-printed carbon electrodes (SPCE*) can be employed for the simultaneous determination of Aminophenol isomers in aqueous buffer solution. In sharp contrast to untreated SPCE, voltammetric studies indicate that the oxidation peak potential of each analyte in an Aminophenol isomer mixture may be separated at the activated SPCE*. The individual oxidation peak currents are greatly increased by first-order derivative techniques. All experimental parameters were optimized to improve responses. The derivative oxidation peak currents is proportional to the concentration of isomer over the range from 0.2 to 100 μM for 2-Aminophenol (2AP), from 3.0 to 200 μM for 3-Aminophenol (3AP), and from 0.2 to 200 μM for 4-Aminophenol (4AP), with detection limits of 0.07, 0.16 and 0.05 μM, respectively. The proposed methods have excellent analytical characteristics that include ease of handling, high sensitivity, wide linear dynamic range and low detection limits. The assay was applied to the simultaneous determination of Aminophenol isomers in river water with good recovery results.
Yuhua Gao - One of the best experts on this subject based on the ideXlab platform.
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amperometric sensor for hydrogen peroxide based on poly aniline co p Aminophenol
2009Co-Authors: Chuanxiang Chen, Cheng Sun, Yuhua GaoAbstract:Abstract It was found that the poly(aniline- co - p -Aminophenol) film can effectively catalyze the oxidation of hydrogen peroxide in a sodium citrate buffer solution with pH 5.0. Here, we applied the copolymer to the construction of an efficient electrochemical sensor to determine the concentration of hydrogen peroxide. The sensor exhibited an excellent electrocatalytic activity toward the oxidation of H 2 O 2 , and the interferences of ascorbic acid and phenol were completely avoided. Unlike the inherent instability of enzyme, the poly(aniline- co - p -Aminophenol) film-based sensor showed an outstanding stability.
