Probing Biomolecular Interactions at Conductive and Semiconductive Surfaces by Impedance Spectroscopy: Routes to Impedimetric Immunosensors, DNA‐Sensors, and Enzyme Biosensors

Abstract

Impedance spectroscopy is a rapidly developing electrochemical technique for the characterization of biomaterialfunctionalized electrodes and biocatalytic transformations at electrode surfaces, and specifically for the transduction of biosensing events at electrodes or field-effect transistor devices. The immobilization of biomaterials, e.g., enzymes, antigens/antibodies or DNA on electrodes or semiconductor surfaces alters the capacitance and interfacial electron transfer resistance of the conductive or semiconductive electrodes. Impedance spectroscopy allows analysis of interfacial changes originating from biorecognition events at electrode surfaces. Kinetics and mechanisms of electron transfer processes corresponding to biocatalytic reactions occurring at modified electrodes can be also derived from Faradaic impedance spectroscopy. Different immunosensors that use impedance measurements for the transduction of antigen-antibody complex formation on electronic transducers were developed. Similarly, DNA biosensors using impedance measurements as readout signals were developed. Amplified detection of the analyte DNA using Faradaic impedance spectroscopy was accomplished by the coupling of functionalized liposomes or by the association of biocatalytic conjugates to the sensing interface providing biocatalyzed precipitation of an insoluble product on the electrodes. The amplified detections of viral DNA and single-base mismatches in DNA were accomplished by similar methods. The changes of interfacial features of gate surfaces of field-effect transistors (FET) upon the formation of antigen-antibody complexes or assembly of protein arrays were probed by impedance measurements and specifically by transconductance measurements. Impedance spectroscopy was also applied to characterize enzymebased biosensors. The reconstitution of apo-enzymes on cofactor-functionalized electrodes and the formation of cofactor-enzyme affinity complexes on electrodes were probed by Faradaic impedance spectroscopy. Also biocatalyzed reactions occurring on electrode surfaces were analyzed by impedance spectroscopy. The theoretical background of the different methods and their practical applications in analytical procedures were outlined in this article.

Label‐Free Impedance Biosensors: Opportunities and Challenges

“…For further reading, we refer the reader to an excellent 2003 review of impedance biosensors by Katz and Willner that focuses on faradaic techniques and impedance amplification using labels [31]. An earlier review of capacitive biosensors includes capacitive biosensors on semiconductor substrates with field-effect contributions [32].…”

Impedance spectroscopy using maximum length sequences: Application to single cell analysis

“…[22][23][24] In all these examples the static or dynamic complex impedance spectrum Z ͑j ͒ of a device, network, or sample contains information on the physicochemical properties. In particular, impedance ͑or dielectric͒ spectroscopy has been used to measure the passive electrical properties of biological cells for many years.…”

Vibrational spectroscopy for probing molecular-level interactions in organic films mimicking biointerfaces

“…biointerfaces). In clinical diagnosis, the fabrication of novel biosensors relies increasingly on functionalized surfaces that may also be considered as biointerfaces [25][26][27][28][29].…”