Modification of Indium Tin Oxide Electrodes with Nucleic Acids:  Detection of Attomole Quantities of Immobilized DNA by Electrocatalysis

Armistead, Paul M.; Thorp, H. Holden

doi:10.1021/ac000051e

Cited by 189 publications

(217 citation statements)

References 55 publications

(78 reference statements)

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“…This is due to the electrochemical oxidation of Ru-dppz followed by the redox reaction between oxidized Ru-dppz and oxalate. Although guanine bases in DNA can also be electro-catalytically oxidized [11], the contribution is negligible because the number of guanines in the film is limited. The catalytic current at 1.3 V in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…So by extrapolation, the lowest amount of DNA on the surface detectable by catalytic voltammetry is 1=20th of 3.2 ng mm À2 , or 160 pg mm À2 . For comparison, Armstead and Thorp reported a detection sensitivity of 44 amol mm À2 , or 40 pg mm À2 by electrocatalysis with dissolved Ru-bpy [11].…”

Section: Resultsmentioning

confidence: 99%

“…Recently, Thorp's group developed a novel approach in labelfree DNA analysis, employing dissolved ruthenium tris (bipyridine) (Ru-bipy) as a redox mediator for the catalytic oxidation of DNA guanines. An impressive detection limit of 40 pg mm À2 was achieved due to the facile electrode kinetics of the mediator and fast second-order reaction between the metal complex and guanine [10][11][12]. The approach was further developed by Rusling and Forster by immobilizing the mediator on the electrode surface [13,14].…”

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confidence: 99%

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Determination of Surface-Immobilized Double-Stranded DNA Using a Metallointercalator and Catalytic Voltammetry

2006

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Abstract. DNA films immobilized on an indium tin oxide (ITO) electrode surface were detected and determined employing a high-affinity intercalator, Ru(bpy) 2 (dppz) 2þ (bpy ¼ 2,2 0 -bipyridine, dppz ¼ dipyrido[3,2-a:2 0 ,3 0 -c]phenazine), as a redox indicator, and oxalate as a sacrificial electron donor in solution to chemically amplify the voltammetric signal of the indicator. Nucleic acids were immobilized on ITO by layer-by-layer electrostatic adsorption, using avidin as the first layer and nucleic acid as the second layer. In quartz crystal microbalance (QCM) measurements on an avidin-coated gold surface, the amount of adsorption from a 200 mg mL À1 nucleic acid solution was found to be 3.2 ng mm À2 for both double-stranded (ds-) and single-stranded (ss-) calf-thymus DNA as well as polycytidylic acid (Poly-C). After binding with Ru(bpy) 2 (dppz) 2þ (Ru-dppz), voltammetry of the ds-DNA film on ITO was carried out in an indicator-free phosphate buffer. An anodic peak at about 1.15 V was observed, and it was assigned to Ru-dppz oxidation. When measured in an oxalate buffer, however, a catalytic current was observed due to the oxidation of oxalate by electrochemically generated Ru(bpy) 2 (dppz) 3þ , resulting in a 120-fold increase in the signal. Since oxalate itself produces a very low oxidation current on ITO, catalytic voltammetry produces about a 14-fold improvement in the signal-to-blank ratio over the nonamplified determination. As a result, ds-DNA adsorbed from 20 ng mL À1 solution could be detected, which was estimated by QCM to be 160 pg mm À2 on the surface. The catalytic current of ds-DNA was substantially higher than that of ss-DNA and poly-C, indicative of selective binding of the redox indicator to ds-DNA. The results serve as a basis for the catalytic voltammetric detection of DNA hybridization in future work.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

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Determination of Surface-Immobilized Double-Stranded DNA Using a Metallointercalator and Catalytic Voltammetry

2006

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“…24 by modifying it with various functionalized groups. 34,35 We prepared an amorphous ITO film using RF sputtering under ambient low oxygen conditions, and found that the amount of phosphate adsorbed on the amorphous ITO film was 4.6-times that adsorbed on a commercially available polycrystalline ITO film, as determined by an XPS study. 36 The reason is that the surface of the amorphous ITO film has more hydroxyl groups, which can react with the phosphates/phosphonates, than that of the polycrystalline ITO film.…”

Section: ·2 Sputtered Nano-film Electrodementioning

confidence: 99%

Newly Developed Chemical Probes and Nano-Devices for Cellular Analysis

et al. 2008

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Homeostasis in an organism is maintained by activities within and between cells. Therefore, one is required to analyze both the cellular activities within cells, such as metabolisms or signal transduction, and cellular interactions, such as ligand-receptor recognition. We have developed a cellular analyzing system including a "real-time cellular imaging system" and a "comprehensive analysis system for cellular responses" as shown in Fig. 1. The system has been established using newly developed chemical probes and nano-devices. As chemical probes, we have developed 1) molecular imaging probes, and 2) mass probes.As nano-devices, we built 1) nano electrochemical and optical probes, 2) a sputtered nano-film electrode, 3) nano-dot SPR, 4) a nano-dot target plate for MS, and 5) microfluidic devices. We will review each of these probes and devices, and finally introduce a "real-time cellular imaging system" with an application model using PC12 cells and a "comprehensive analysis system for cellular responses", which measured IL-1β (interleukin-1β) as an example. Chemical Probes 2·1 Molecular imaging probesFluorescent imaging based on fluorescent probes offers a highly sensitive, high-speed spatial and temporal analysis of cells, and is widely used in the fields of biology and physiology. A cellular analyzing system including a "real-time cellular imaging system" and a "comprehensive analyzing system for cellular responses" was developed. A "real-time cellular imaging system" is a system used to measure real-time imaging of multiple phenomena of a single cell with high special and temporal resolutions for the purpose to understand the pathology and physiology in a single cell and realize to single cell level diagnosis. A "real-time cellular imaging system" includes multi-probe imaging with AFM (atomic force microscopy), optical and SECM (scanning electrochemical microscopy) modes, which provides us with topological information and biochemical reactions at the local area of the interior and exterior of a cell. Scanning electrochemical/optical microscopy was applied to image PC12 cells. On the other hand, cells respond to their specific substances via their ligands. Therefore, the comprehensive analysis of protein-protein interaction is the important issue to determine the functions of cells. For this purpose, a "comprehensive analysis system for cellular responses" was developed. This system is based on SPR (surface plasmon resonance) and MS (mass spectrometry) using a nano-fabricated substrate. The interaction between IL-1β and anti-IL-1β antibodies was detected.

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“…However, the guanine oxidation is irreversible, and almost all of the guanine bases are consumed in the first scan (28 ). The peak currents in the second and third scans are therefore essentially from Ru(bpy) 3 2ϩ alone:…”

Section: Electrochemical Detection Algorithm Ac Voltammetry (Acv)mentioning

confidence: 99%

Miniaturized Multiplex Label-Free Electronic Chip for Rapid Nucleic Acid Analysis Based on Carbon Nanotube Nanoelectrode Arrays

et al. 2004

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Background:Reducing cost and time is the major concern in clinical diagnostics, particularly in molecular diagnostics. Miniaturization technologies have been recognized as promising solutions to provide low-cost microchips for diagnostics. With the recent advancement in nanotechnologies, it is possible to further improve detection sensitivity and simplify sample preparation by incorporating nanoscale elements in diagnostics devices. A fusion of micro-and nanotechnologies with biology has great potential for the development of low-cost disposable chips for rapid molecular analysis that can be carried out with simple handheld devices. Approach: Vertically aligned multiwalled carbon nanotubes (MWNTs) are fabricated on predeposited microelectrode pads and encapsulated in SiO 2 dielectrics with only the very end exposed at the surface to form an inlaid nanoelectrode array (NEA). The NEA is used to collect the electrochemical signal associated with the target molecules binding to the probe molecules, which are covalently attached to the end of the MWNTs. Content: A 3 ؋ 3 microelectrode array is presented to demonstrate the miniaturization and multiplexing capability. A randomly distributed MWNT NEA is fabricated on each microelectrode pad. Selective functionalization of the MWNT end with a specific oligonucleotide probe and passivation of the SiO 2 surface with ethylene glycol moieties are discussed. Ru(bpy) 2؉ -mediator-amplified guanine oxidation is used to directly measure the electrochemical signal associated with target molecules.

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Modification of Indium Tin Oxide Electrodes with Nucleic Acids: Detection of Attomole Quantities of Immobilized DNA by Electrocatalysis

Cited by 189 publications

References 55 publications

Determination of Surface-Immobilized Double-Stranded DNA Using a Metallointercalator and Catalytic Voltammetry

Determination of Surface-Immobilized Double-Stranded DNA Using a Metallointercalator and Catalytic Voltammetry

Newly Developed Chemical Probes and Nano-Devices for Cellular Analysis

Miniaturized Multiplex Label-Free Electronic Chip for Rapid Nucleic Acid Analysis Based on Carbon Nanotube Nanoelectrode Arrays

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