Direct Measurement of a Biomarker’s Native Optimal Frequency with Physical Adsorption Based Immobilization

The optimal frequency (OF) of a biomarker in electrochemical impedance spectroscopy (EIS) is the frequency at which the EIS response best reflects the binding of the biomarker to its molecular recognition element. Commonly, biosensors rely on complicated immobilization chemistry to attach biological molecules to the sensor surface, making the direct study of a biomarker’s native OF a challenge. Physical adsorption presents a simple immobilization strategy to study the native biomarker’s OF, but its utility is often discouraged due to a loss in biological activity. To directly study a biomarker’s native OF and investigate the potential of OF to overcome the limitations of physical adsorption, a combination of EIS and glutaraldehyde-mediated physical adsorption was explored. The experimental sensing platform was prepared by immobilizing either anti-lactoferrin (Lfn) IgG or anti-immunoglobulin E (IgE) onto screen printed carbon electrodes. After characterizing the native OFs of both biomarkers, investigation...