title: Quantifying the effect of ionic screening with protein-decorated graphene transistors.
abstract: Liquid-based applications of biomolecule-decorated field-effect transistors (FETs) range from biosensors to in vivo implants. A critical scientific challenge is to develop a quantitative understanding of the gating effect of charged biomolecules in ionic solution and how this influences the readout of the FETs. To address this issue, we fabricated protein-decorated graphene FETs and measured their electrical properties, specifically the shift in Dirac voltage, in solutions of varying ionic strength. We found excellent quantitative agreement with a model that accounts for both the graphene polarization charge and ionic screening of ions adsorbed on the graphene as well as charged amino acids associated with the immobilized protein. The technique and analysis presented here directly couple the charging status of bound biomolecules to readout of liquid-phase FETs fabricated with graphene or other two-dimensional materials.
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia 19104, USA.
authors.forename: Jinglei
authors.initials: J
authors.lastname: Ping
authors.affiliation: Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Jin
authors.initials: J
authors.lastname: Xi
authors.affiliation: Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Jeffery G
authors.initials: JG
authors.lastname: Saven
authors.affiliation: Department of Anesthesiology and Critical Care, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA.
authors.forename: Renyu
authors.initials: R
authors.lastname: Liu
authors.affiliation: Department of Physics and Astronomy, University of Pennsylvania, Philadelphia 19104, USA. Electronic address: cjohnson@sas.upenn.edu.
authors.forename: A T Charlie
authors.initials: ATC
authors.lastname: Johnson
mesh_terms: D015374:Biosensing Techniques / Q000295:instrumentation*; D004553:Electric Conductivity; D004867:Equipment Design; D006108:Graphite / Q000737:chemistry*; D006801:Humans; D055767:Immobilized Proteins / Q000737:chemistry*; D009994:Osmolar Concentration; D017450:Receptors, Opioid, mu / Q000737:chemistry*; D055672:Static Electricity; D014173:Transistors, Electronic
chemical_list: D055767:Immobilized Proteins; D017450:Receptors, Opioid, mu; D006108:Graphite
keywords: Field effect transistor; Graphene; Ionic screening; Redesigned GPCR