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Real-Time Label-Free Direct Electronic Monitoring of Topoisomerase Enzyme Binding Kinetics on Graphene

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journal contribution
posted on 24.11.2015, 00:00 by Laura Zuccaro, Cinzia Tesauro, Tetiana Kurkina, Paola Fiorani, Hak Ki Yu, Birgitta R. Knudsen, Klaus Kern, Alessandro Desideri, Kannan Balasubramanian
Monolayer graphene field-effect sensors operating in liquid have been widely deployed for detecting a range of analyte species often under equilibrium conditions. Here we report on the real-time detection of the binding kinetics of the essential human enzyme, topoisomerase I interacting with substrate molecules (DNA probes) that are immobilized electrochemically on to monolayer graphene strips. By monitoring the field-effect characteristics of the graphene biosensor in real-time during the enzyme–substrate interactions, we are able to decipher the surface binding constant for the cleavage reaction step of topoisomerase I activity in a label-free manner. Moreover, an appropriate design of the capture probes allows us to distinctly follow the cleavage step of topoisomerase I functioning in real-time down to picomolar concentrations. The presented results are promising for future rapid screening of drugs that are being evaluated for regulating enzyme activity.