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

2008; American Chemical Society; Volume: 80; Issue: 3 Linguagem: Inglês

10.1021/ac701910r

1520-6882

Apon Numnuam, Karin Y. Chumbimuni‐Torres, Yun Xiang, R. Bash, Panote Thavarungkul, Proespichaya Kanatharana, Ernö Pretsch, Joseph Wang, Eric Bakker,

Electrochemical Analysis and Applications

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 μL microwells, using a calcium-selective electrode as a pseudoreference electrode. As a prototype example, thrombin was measured in 200 μL 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.