Abstract:

An electrochemical biosensor has been developed for ultrasensitive, label-free determination of protein kinase activity. The sensor is composed of a unique peptide monolayer on a gold electrode. It identifies the order change in the monolayer upon phosphorylation, via square wave voltametry (SWV) measurements. Disorder caused by the introduction of the phosphate groups onto the middle of the peptide sequence results in pinhole formation and therefore an increase in the electrochemical signal. The measured sensitivity was 100 nM of kinase and the dynamic range was 100 nM up to 11 μM. Sensitivity was an order of magnitude higher, and the dynamic range wider by two orders of magnitude, as compared to our previously reported impedimetric method, in which the sensitivity was 1 μM, and the dynamic range was 1-20 μM.

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