Capacitive Biosensing Technique for the Detection of DNA Modification and Hybridization Process Using Custom- made Gold Interdigital Microelectrode Arrays

摘要

Interest in miniaturized bio-sensing techniques has grown in the past decades for the rapid and accurate detection of disease-causing agents. Innovative custom microdevices provide a greener approach by reducing the cost and waste in terms of sample amount, reagent volumes, size, time and human resources. This is particularly important for outer space environment where timing is crucial and laboratory facilities are not available. Here, we propose a non-faradaic, label-free, electrochemical method based on capacitance measurement to sense DNA surface modification and hybridization. We created custom- made gold interdigital microelectrodes arrays using photolithography technique. Silver electroplating was used to make a stable silver silver/chloride quasi-reference electrode. Self assembled monolayers of B. Anthracis aptamer at two different surface coverage were made and exposed to complementary, non-complementary and mismatch strands to study the hybridization and/or non-hybridization processes by means of double layer capacitance (C_(dl)) measurements at two given applied potentials using Electrochemical Impedance Spectroscopy (EIS) analysis. An average percentage change in C_(dl) of 31.0% and 19.8% were obtained for the low and high Anthracis aptamer coverage respectively when exposed to its complementary target. The conditions that showed better distinction between strand interactions, as well as lower error bars, were low surface coverage at 0.3V vs. E_(oc) applied potential. Overall results showed that double layer capacitance is a measurable property to detect specific DNA sequences.