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Aptamer-Based Potentiometric Measurements of Proteins Using Ion-Selective Microelectrodes

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Authors
Numnuam, A.
Chumbimuni-Torres, K.
Xiang, Y.
Bash, R.
Thavarungkul, P.
Kanatharana, P.
Pretsch, E.
Wang, J.
Bakker, Eric
Date
2008
Type
Journal Article

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Citation
Numnuam, Apon and Chumbimuni-Torres, Karin Y. and Xiang, Yun and Bash, Ralph and Thavarungkul, Panote and Kanatharana, Proespichaya and Pretsch, Ern and Wang, Joseph and Bakker, Eric. 2008. Aptamer-Based Potentiometric Measurements of Proteins Using Ion-Selective Microelectrodes. Analytical Chemistry 80 (3): 707-712.
Source Title
Analytical Chemistry
DOI
Faculty
Nanochemistry Research Centre
School
Nanochemistry Research Institute (Research Institute)
URI
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Abstract

We here report on the first example of an aptamer-based potentiometric sandwich assay of proteins. The measurements are based on CdS quantum dot labels of the secondary aptamer, which were determined with a novel solid-contact Cd2+-selective polymer membrane electrode after dissolution with hydrogen peroxide. The electrode exhibited cadmium ion detection limits of 100 pM in 100 mL samples and of 1 nM in 200 microwells, using a calcium-selective electrode as a pseudoreference electrode. As a prototype example, thrombin was measured in 200 samples with a lower detection limit of 0.14 nM corresponding to 28 fmol of analyte. The results show great promise for the potentiometric determination of proteins at very low concentrations in microliter samples.