title: Capacitance-modulated transistor detects odorant binding protein chiral interactions.
abstract: Peripheral events in olfaction involve odorant binding proteins (OBPs) whose role in the recognition of different volatile chemicals is yet unclear. Here we report on the sensitive and quantitative measurement of the weak interactions associated with neutral enantiomers differentially binding to OBPs immobilized through a self-assembled monolayer to the gate of an organic bio-electronic transistor. The transduction is remarkably sensitive as the transistor output current is governed by the small capacitance of the protein layer undergoing minute changes as the ligand-protein complex is formed. Accurate determination of the free-energy balances and of the capacitance changes associated with the binding process allows derivation of the free-energy components as well as of the occurrence of conformational events associated with OBP ligand binding. Capacitance-modulated transistors open a new pathway for the study of ultra-weak molecular interactions in surface-bound protein-ligand complexes through an approach that combines bio-chemical and electronic thermodynamic parameters.
authors.affiliation: Dipartimento di Chimica and CSGI, Università degli Studi di Bari 'Aldo Moro', 70125 Bari, Italy.
authors.forename: Mohammad Yusuf
authors.initials: MY
authors.lastname: Mulla
authors.affiliation: School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL, UK.
authors.forename: Elena
authors.initials: E
authors.lastname: Tuccori
authors.affiliation: Dipartimento di Chimica and CSGI, Università degli Studi di Bari 'Aldo Moro', 70125 Bari, Italy.
authors.forename: Maria
authors.initials: M
authors.lastname: Magliulo
authors.affiliation: Dipartimento di Fisica 'M. Merlin', INFN and TIRES, Università degli Studi di Bari 'Aldo Moro', 70125 Bari, Italy.
authors.forename: Gianluca
authors.initials: G
authors.lastname: Lattanzi
authors.affiliation: Dipartimento di Chimica and CSGI, Università degli Studi di Bari 'Aldo Moro', 70125 Bari, Italy.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Palazzo
authors.affiliation: School of Chemical Engineering and Analytical Science, The University of Manchester, Manchester M13 9PL, UK.
authors.forename: Krishna
authors.initials: K
authors.lastname: Persaud
authors.affiliation: Dipartimento di Chimica and CSGI, Università degli Studi di Bari 'Aldo Moro', 70125 Bari, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Torsi
mesh_terms: D025802:Electric Capacitance; D011485:Protein Binding; D018035:Receptors, Odorant / Q000737:chemistry* / Q000378:metabolism*; D013237:Stereoisomerism; D014173:Transistors, Electronic
chemical_list: D018035:Receptors, Odorant; C045648:odorant-binding protein