The Development of a Label-Free Electrochemical Impedance Based Pointof-care Technology for Multimarker Detection

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With an increasing global population, rising healthcare costs, and greater demand on hospitals and clinicians, a growing need for low cost, rapid, Point of Care Technologies (POCT) exists. The overall goal is to detect or monitor a disease in order to give patients and clinicians fast, accurate, and all-encompassing information regarding the state of the disease. A challenge for many currentpoint-of-care technologies is the difficulty of monitoring several biomarkers simultaneously without the complexity of multiple sensors, labels, or spatially separated transducers. We have previously shown that convoluted signals obtained from protein biomarkers monitored by electrochemical impedance spectroscopy can be “tuned” away from one another by conjugation with gold nanoparticles to allow for the potential simultaneous detection of multiple biomarkers. This method of detection yields a sensitive and specific means of biomarker quantification in human media including tears or blood. In this work, we detail the development of a mathematical model that explores the roles of various factors, such as nanoparticle size and the nature of materials, so that a design space could be created for tuningotherwise convoluted biomarkers. Furthermore, we present assessments as to the validity of this model with preliminary bench-top experiments by taking advantage of gold nanoparticle-antibody conjugates of varying sizes. Gold nanoparticle size changes of 5, 10, and 20 nm demonstrated a 10.0, 4.8, and 1.0 Hz shift in frequency, respectively. Future work includes exploration of different sensor configurations, continuous monitoring, and the prospect for implantable sensors were also discussed as potential future avenues.