Separation Techniques

The immersion of biosensors in body tissue samples inevitably involves the formation of interfaces with body electrolytes. The interfaces are generally viewed as nuisances to recognizances of antibodies to which nanostructures comprising the biosensor surfaces have been sensitized. This is because the interfaces can interfere with sophisticated electronic and chemical constructs comprising the biosensor substrates that transduce and amplify signals generated by targeted antibodies upon binding tocomplementary antigens anchored within the nanostructures. The interfacial impedimetric biosensor avoids this sophistication butuses electrical impedance spectroscopy (EIS) to characterize electrochemical and physiochemical changes in the interface where antibody-antigen bindings occur. EIS, XPS and water-contact-angle measurements were used to characterize the surfaces andinterfaces that alkane nanostructures formed with 1-300 mM KCl electrolytes during the construction of the biosensor. EIS alsocharacterized the interfaces that formed between the nanostructures and the highly doped semiconductor substrate. This confirmedthe absence of the usual electric field inducing depletion layers that develop in low doped semiconductor substrates and the absenceof dependencies of the interfacial properties on electrolyte concentration. Such remained the case during the construction whichcommenced with an undecylenic acid nanostructure and progressed through stages of surface modifications with NHS, IgG andglycine. The interfaces that formed with the electrolytes varied but in explainable ways related to thicknesses, surface coverage’s and electronegativity of the modifications as well as electrolyte concentrations. The interfacial recognizance of the targeted anti-IgG wasunambiguously confirmed by non-specific binding tests with anti-IgM. Future development stages will be discussed.