Suppressing Non-Specific Binding of Proteins onto Electrode Surfaces in the Development of Electrochemical Immunosensors

Abstract

Electrochemical immunosensors, EIs, are systems that combine the analytical power of electrochemical techniques and the high selectivity and specificity of antibodies in a solid phase immunoassay for target analyte. In EIs, the most used transducer platforms are screen printed electrodes, SPEs. Some characteristics of EIs are their low cost, portability for point of care testing (POCT) applications, high specificity and selectivity to the target molecule, low sample and reagent consumption and easy to use. Despite all these attractive features, still exist one to cover and it is the enhancement of the sensitivity of the EIs. In this review, an approach to understand how this can be achieved is presented. First, it is necessary to comprise thoroughly all the complex phenomena that happen simultaneously in the protein-surface interface when adsorption of the protein occurs. Physicochemical properties of the protein and the surface as well as the adsorption phenomena influence the sensitivity of the EIs. From this point, some strategies to suppress non-specific binding, NSB, of proteins onto electrode surfaces in order to improve the sensitivity of EIs are mentioned.

Developments in biosensors for CoV detection and future trends

“…Chemical modification and functionalization of the electrode surface is generally performed to suppress the NSB and, at the same time, to enhance the biocompatibility of the electrode surface towards antibodies or proteins and the biosensor sensitivity. Thiol terminated polyethylene glycol (PEG) has become quite popular for reducing NSB, by forming self-assembled monolayers (SAM) on the metal coated sensor electrode, providing also functional groups for surface immobilization ( Contreras-Naranjo and Aguilar, 2019 ).…”

Integrated Electrochemical Biosensors for Detection of Waterborne Pathogens in Low-Resource Settings

“…This is due to the relatively low concentrations of biomarkers within water environments [133]. Additionally, in complex biological samples, sensitivity of biosensors may be decreased due to low levels of non-specific binding [134,135]. There are several different methods for the preconcentration of proteins and cells as well as the amplification of nucleic acid biomarkers used regularly within laboratory settings.…”

Printed Electrodes in Microfluidic Arrays for Cancer Biomarker Protein Detection

“…( Scheme 1 F) NSB arises when the Ab 2 molecules bind to non-antigen sites of the electrodes, providing a signal which is not proportionate to the analyte concentration, increasing the LOD and damaging the sensitivity. Casein and BSA are used to prevent NSB by sterically blocking the non-analyte sites, whereas detergent such as phosphate-buffered saline-Tween 20 (PBS-T20) or Tris buffer solution (TBS), with sodium dodecyl sulfate (SDS) or Triton 100-X, help to wash away weakly-bound Ab 2 on non-analyte sites [ 17 , 56 ]. Another approach on reduction of NSB is through chemical attachments of the electrode surface to reduce protein adsorption through (a) polymerization strategies (polyethylene glycol (PEG), conducting polymers), (b) modification of allotropic carbons (carbon nanotubes), (c) sol-gel modification, (d) surface modification by diazonium salts, (e) metal nanoparticles (magnetic beads, gold and silver nanoparticles), (f) self-assembled monolayers (SAMs) [ 52 ].…”

“…Electrode arrays were insulated with a printed overcoating of poly(amic) acid, a precursor that converts to Kapton when heated. The inkjet-printed working electrodes had reproducible surface areas with relative standard deviation (RSD) < 3% [ 56 , 57 ]. The material cost was $0.2 [ 31 , 98 ].…”