title: A quantitative study of detection mechanism of a label-free impedance biosensor using ultrananocrystalline diamond microelectrode array.
abstract: It is well recognized that label-free biosensors are the only class of sensors that can rapidly detect antigens in real-time and provide remote environmental monitoring and point-of-care diagnosis that is low-cost, specific, and sensitive. Electrical impedance spectroscopy (EIS) based label-free biosensors have been used to detect a wide variety of antigens including bacteria, viruses, DNA, and proteins due to the simplicity of their detection technique. However, their commercial development has been hindered due to difficulty in interpreting the change in impedance upon antigen binding and poor signal reproducibility as a result of surface fouling and non-specific binding. In this study, we develop a circuit model to adequately describe the physical changes at bio functionalized surface and provide an understanding of the detection mechanism based on electron exchange between electrolyte and surface through pores surrounding antibody-antigen. The model was successfully applied to extract quantitative information about the bio surface at different stages of surface functionalization. Further, we demonstrate boron-doped ultrananocrystalline diamond (UNCD) microelectrode array (3 × 3 format, 200 μm diameter) improves signal reproducibility significantly and increases sensitivity by four orders of magnitude. This study marks the first demonstration of UNCD array based biosensor that can reliably detect a model Escherichia coli K12 bacterium using EIS, positioning this technology for rapid adoption in point-of-use applications.
authors.affiliation: Advanced Diamond Technologies, Inc., 429 B Weber Road #286, Romeoville, IL 60446, USA.
authors.forename: Shabnam
authors.initials: S
authors.lastname: Siddiqui
authors.affiliation: Advanced Diamond Technologies, Inc., 429 B Weber Road #286, Romeoville, IL 60446, USA.
authors.forename: Zhenting
authors.initials: Z
authors.lastname: Dai
authors.affiliation: Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, WI 53706, USA.
authors.forename: Courtney J
authors.initials: CJ
authors.lastname: Stavis
authors.affiliation: Advanced Diamond Technologies, Inc., 429 B Weber Road #286, Romeoville, IL 60446, USA.
authors.forename: Hongjun
authors.initials: H
authors.lastname: Zeng
authors.affiliation: Advanced Diamond Technologies, Inc., 429 B Weber Road #286, Romeoville, IL 60446, USA.
authors.forename: Nicolaie
authors.initials: N
authors.lastname: Moldovan
authors.affiliation: Department of Chemistry, University of Wisconsin, 1101 University Avenue, Madison, WI 53706, USA.
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Hamers
authors.affiliation: Advanced Diamond Technologies, Inc., 429 B Weber Road #286, Romeoville, IL 60446, USA.
authors.forename: John A
authors.initials: JA
authors.lastname: Carlisle
authors.affiliation: Advanced Diamond Technologies, Inc., 429 B Weber Road #286, Romeoville, IL 60446, USA. Electronic address: prabhu@thindiamond.com.
authors.forename: Prabhu U
authors.initials: PU
authors.lastname: Arumugam
mesh_terms: D000907:Antibodies, Bacterial; D055910:Antibodies, Immobilized; D000941:Antigens / Q000032:analysis*; D000942:Antigens, Bacterial / Q000032:analysis; D015374:Biosensing Techniques / Q000379:methods* / Q000706:statistics & numerical data; D018130:Diamond; D058266:Dielectric Spectroscopy; D055664:Electrochemical Techniques; D048168:Escherichia coli K12 / Q000276:immunology / Q000302:isolation & purification; D008839:Microelectrodes; D053758:Nanoparticles / Q000648:ultrastructure; D015203:Reproducibility of Results; D013499:Surface Properties
chemical_list: D000907:Antibodies, Bacterial; D055910:Antibodies, Immobilized; D000941:Antigens; D000942:Antigens, Bacterial; D018130:Diamond