title: Complementarity of EIS and SPR to reveal specific and nonspecific binding when interrogating a model bioaffinity sensor; perspective offered by plasmonic based EIS.
abstract: The present work compares the responses of a model bioaffinity sensor based on a dielectric functionalization layer, in terms of specific and nonspecific binding, when interrogated simultaneously by Surface Plasmon Resonance (SPR), non-Faradaic Electrochemical Impedance Spectroscopy (EIS), and Plasmonic based-EIS (P-EIS). While biorecognition events triggered a sensitive SPR signal, the related EIS response was rather negligible. Contrarily, even a limited nonspecific adsorption onto the surface of the metallic electrode, allowed by the intrinsic imperfect compactness of the functionalization layers, was signaled by EIS and not by SPR. The source of this finding has been addressed from both theoretical and experimental perspectives, demonstrating that EIS signals are mainly sensitive to adsorptions that alter the current pathway through defects of the functionalization layer exposing the electrode. These observations are of importance for those developing biosensors analyzed by SPR, EIS, or the novel combination of the two methods (P-EIS). A possible application of the observed complementarity of the two methods, namely assessment of sample purity in respect to a target analyte is highlighted. Moreover, the possibility of false-positive EIS responses (determined by nonspecific binding) when assessing samples containing complex matrices or consisting of small molecular weight analytes is emphasized.
authors.affiliation: International Centre of Biodynamics , 1B Intrarea Portocalelor, 060101 Bucharest, Romania.
authors.forename: Cristina
authors.initials: C
authors.lastname: Polonschii
authors.forename: Sorin
authors.initials: S
authors.lastname: David
authors.forename: Szilveszter
authors.initials: S
authors.lastname: Gáspár
authors.forename: Mihaela
authors.initials: M
authors.lastname: Gheorghiu
authors.forename: Mihnea
authors.initials: M
authors.lastname: Rosu-Hamzescu
authors.forename: Eugen
authors.initials: E
authors.lastname: Gheorghiu
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002417:Cattle; D058266:Dielectric Spectroscopy; D007074:Immunoglobulin G / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D012709:Serum Albumin / Q000737:chemistry / Q000378:metabolism; D020349:Surface Plasmon Resonance
chemical_list: D007074:Immunoglobulin G; D012709:Serum Albumin