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Open Access Highly Accessed Research article

Electrical protein detection in cell lysates using high-density peptide-aptamer microarrays

David Evans1, Steven Johnson1, Sophie Laurenson2, A Giles Davies1, Paul Ko Ferrigno23 and Christoph Wälti1*

Author affiliations

1 School of Electronic and Electrical Engineering, University of Leeds, Leeds LS2 9JT, UK

2 MRC Cancer Cell Unit, Hutchison/MRC Research Centre, Hills Road, Cambridge CB2 2XZ, UK

3 Leeds Institute of Molecular Medicine, St James' University Hospital, Leeds LS9 7TF, UK

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Citation and License

Journal of Biology 2008, 7:3  doi:10.1186/jbiol62

Published: 31 January 2008

Abstract

Background

The dissection of biological pathways and of the molecular basis of disease requires devices to analyze simultaneously a staggering number of protein isoforms in a given cell under given conditions. Such devices face significant challenges, including the identification of probe molecules specific for each protein isoform, protein immobilization techniques with micrometer or submicrometer resolution, and the development of a sensing mechanism capable of very high-density, highly multiplexed detection.

Results

We present a novel strategy that offers practical solutions to these challenges, featuring peptide aptamers as artificial protein detectors arrayed on gold electrodes with feature sizes one order of magnitude smaller than existing formats. We describe a method to immobilize specific peptide aptamers on individual electrodes at the micrometer scale, together with a robust and label-free electronic sensing system. As a proving proof of principle experiment, we demonstrate the specific recognition of cyclin-dependent protein kinases in whole-cell lysates using arrays of ten electrodes functionalized with individual peptide aptamers, with no measurable cross-talk between electrodes. The sensitivity is within the clinically relevant range and can detect proteins against the high, whole-cell lysate background.

Conclusion

The use of peptide aptamers selected in vivo to recognize specific protein isoforms, the ability to functionalize each microelectrode individually, the electronic nature and scalability of the label-free detection and the scalability of the array fabrication combine to yield the potential for highly multiplexed devices with increasingly small detection areas and higher sensitivities that may ultimately allow the simultaneous monitoring of tens or hundreds of thousands of protein isoforms.