Biosensors based on graphene field-effect transistors have become a promising tool for detecting a broad range of analytes. However, their performance is substantially affected by the functionalization protocol. In this work, we use a controlled in-vacuum physical method for the covalent functionalization of graphene to construct ultrasensitive aptamer-based biosensors (aptasensors) able to detect hepatitis C virus core protein. These devices are highly specific and robust, achieving attomolar detection of the viral protein in human blood plasma. Such an improved sensitivity is rationalized by theoretical calculations showing that induced polarization at the graphene interface, caused by the proximity of covalently bound molecular probe, modulates the charge balance at the graphene/aptamer interface. This charge balance causes a net shift of the Dirac cone providing enhanced sensitivity for the attomolar detection of the target proteins. Such an unexpected effect paves the way for using this kind of graphene-based functionalized platforms for ultrasensitive and real-time diagnostics of different diseases.

Centro de Astrobiología 28850 Torrejón de Ardoz Madrid Spain

Centro de Astrobiología 28850 Torrejón de Ardoz Madrid Spain; Universidad de Alcalá Facultad de Medicina Madrid Spain

Centro de Astrobiología Instituto de Salud Carlos 3 Madrid Spain

Department of Chemistry in Pharmaceutical Sciences Faculty of Pharmacy Complutense University Plaza Ramón y Cajal 28040 Madrid Spain

Institute of Material Science of Madrid C Sor Juana Inés de La Cruz 3 28049 Madrid Spain

Institute of Physics Czech Academy of Sciences 16200 Prague Czech Republic

International Iberian Nanotechnology Laboratory 4715 330 Braga Portugal

International Iberian Nanotechnology Laboratory Universidade do Minho 4710 057 Braga Portugal

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