title: Label-free C-reactive protein electronic detection with an electrolyte-gated organic field-effect transistor-based immunosensor.
abstract: In this contribution, we propose a label-free immunosensor, based on a novel type of electrolyte-gated field-effect transistor (EGOFET), for ultrasensitive detection of the C-reactive protein (CRP). The recognition layer of the biosensor is fabricated by physical adsorption of the anti-CRP monoclonal antibody onto a poly-3-hexyl thiophene (P3HT) organic semiconductor surface. A supplementary nonionic hydrophilic polymer is used as a blocking agent preventing nonspecific interactions and allowing a better orientation of the antibodies immobilized onto the P3HT surface. The whole biomolecule immobilization procedure does not require any pretreatment of the organic semiconductor surface, and the whole functionalization process is completed in less than 30 min. Surface plasmon resonance (SPR) measurements were performed to assess the amount of biomolecules physisorbed onto the P3HT and to evaluate the CRP binding proprieties of the deposited anti-CRP layer. A partial surface coverage of about 23 % of adsorbed antibody molecules was found to most efficiently sense the CRP. The electrical performance of the EGOFET immunosensor was comparable to that of a bare P3HT EGOFET device, and the obtained CRP calibration curve was linear over six orders of magnitude (from 4 pM to 2 μM). The relative standard deviation of the individual calibration points, measured on immunosensors fabricated on different chips, ranged between 1 and 14 %, and a detection limit of 2 pM (220 ng/L) was established. The novel electronic immunosensor is compatible with low-cost fabrication procedures and was successfully employed for the detection of the CRP biomarker in the clinically relevant matrix serum. Graphical abstract Schematic of the EGOFET immunosensor for CRP detection. The anti-CRP monoclonal antibody layer is physisorbed on the P3HT organic semiconductor and the CRP is directly measured by a label-free electronic EGOFET transducer.
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Bari "Aldo Moro" and GSI, Via Orabona 4, 70126, Bari, Italy. maria.magliulo@uniba.it.
authors.forename: Maria
authors.initials: M
authors.lastname: Magliulo
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Bari "Aldo Moro" and GSI, Via Orabona 4, 70126, Bari, Italy.
authors.forename: Donato
authors.initials: D
authors.lastname: De Tullio
authors.affiliation: BioMediTech, University of Tampere, Fimlab Laboratories Ltd., 33520, Tampere, Finland.
authors.forename: Inger
authors.initials: I
authors.lastname: Vikholm-Lundin
authors.affiliation: BioNavis OY, Elopellontie 3.C, 33470, Ylöjärvi, Finland.
authors.forename: Willem M
authors.initials: WM
authors.lastname: Albers
authors.affiliation: VTT Technical Research Centre of Finland, Process Chemistry and Environmental Engineering, Sinitaival 6, 33720, Tampere, Finland.
authors.forename: Tony
authors.initials: T
authors.lastname: Munter
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Bari "Aldo Moro" and GSI, Via Orabona 4, 70126, Bari, Italy.
authors.forename: Kyriaki
authors.initials: K
authors.lastname: Manoli
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Bari "Aldo Moro" and GSI, Via Orabona 4, 70126, Bari, Italy.
authors.forename: Gerardo
authors.initials: G
authors.lastname: Palazzo
authors.affiliation: Dipartimento di Chimica, Università degli Studi di Bari "Aldo Moro" and GSI, Via Orabona 4, 70126, Bari, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Torsi
mesh_terms: D000327:Adsorption; D000906:Antibodies / Q000737:chemistry; D055910:Antibodies, Immobilized; D015374:Biosensing Techniques / Q000295:instrumentation / Q000379:methods*; D002097:C-Reactive Protein / Q000032:analysis*; D004573:Electrolytes / Q000737:chemistry; D007118:Immunoassay / Q000295:instrumentation / Q000379:methods*; D057230:Limit of Detection; D012666:Semiconductors; D013876:Thiophenes / Q000737:chemistry
chemical_list: D000906:Antibodies; D055910:Antibodies, Immobilized; D004573:Electrolytes; D013876:Thiophenes; D002097:C-Reactive Protein
keywords: C-reactive protein; Electrolyte-gated organic field-effect transistor; Immunosensor; Label-free electronic detection