Selective immobilization of DNA and antibody probes on electrode arrays: Simultaneous electrochemical detection of DNA and protein on a single platform
ABSTRACT A proof of concept procedure for the electroaddressable covalent immobilization of DNA and protein on arrayed electrodes along with simultaneous detection of multiple bioagents in the same sample solution is described. Carboxyphenyldiazonium was selectively deposited onto five of nine individually addressable electrodes in an array via bias assisted assembly. Amine functionalized DNA probes were covalently coupled to the carboxyl surface via carbodiimide chemistry. This was followed by the covalent immobilization of diazonium-antibody conjugates into the remaining four electrodes via cyclic voltammetry. Simultaneous electrochemical detection of a DNA sequence related to the breast cancer BRCA1 gene and the human cytokine protein interleukin-12, which is a substantial component in the immune system response and attack of tumor cells, is reported. These results demonstrate the possibility of selective patterning of diverse biomolecules on a single device and may have significant implications for future development of microarrays and biosensors.
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ABSTRACT: This paper reviews past and current developments in the field of electrochemical biosensors with a focus on the sequence-specific detection of nucleic acids in real samples. After electrochemical hybridization sensors had been first described in 1993, it took nearly a decade until some of the many proposed protocols were indeed applied to real samples like blood or tissue. Electrochemical transduction schemes used either rely on electroactive moieties such as intercalators, groove binders, covalently attached labels, and products of enzyme markers or they are completely indicator free like impedance-based detection principles. Most detection schemes require a polymerase chain reaction amplification step to allow for sufficient selectivity and sensitivity. Today, several companies develop electrochemical microarrays able to detect dozens to many thousands of sequences in a single experiment. KeywordsElectrochemical biosensor–Hybridization detection–Real sample–Intercalator–Redox label–Indicator freeBioanalytical Reviews 12/2010; 2(1):103-114. DOI:10.1007/s12566-010-0014-x
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ABSTRACT: In this article we review recent work in our laboratory towards the realization of a multianalyte microelectrode detection platform capable of discriminating chemicals and different biomolecules simultaneously. The functionalization of electrodes with aryl diazonium salts provides an electrically addressable deposition procedure capable of immobilizing a wide range of molecules. We demonstrate control over surface density and electron transfer kinetics as well as the activation of individual electrodes in an array. The direct electrically-addressable immobilization of diazonium-modified proteins is shown to be suitable for the construction of multianalyte immunosensors and the immobilization of horseradish peroxidase leading to the direct electron transfer between the redox enzyme and the electrode. The use of catalytic nanoparticles leads to the construction of a reagent-less immunosensor and the simultaneous detection of DNA and proteins on the same electrode array is demonstrated.Electroanalysis 02/2008; 20(6):671 - 679. DOI:10.1002/elan.200704129 · 2.50 Impact Factor
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ABSTRACT: (Chemical Equation Presented) Holding cells: Individual gold electrodes can be activated by phenylboronic acid diazonium salts for the facile and reversible immobilization of eukaryotic cells (see scheme). This platform provides a simple method for on-demand release of captured cells (yeast and macrophage) and can be used in single-cell or array-based studies.Angewandte Chemie International Edition 03/2008; 47(14):2631-4. DOI:10.1002/anie.200704597 · 11.26 Impact Factor