| When certain antigens are present in our environment, a rapid, on-site, accurate, selective, and repeatable detection method can be invaluable in preventing illness or saving lives. Rapid detection of these antigens is important to avert spreading infections.;Currently, capturing a sample and sending it to a laboratory can take weeks to get results, which can be much too long. Conventional sensing methodologies include various electrical measurements as capacitive, potentiometric, piezoelectric, surface plasmon resonance (SPR), and quartz crystal microbalance (QCM). Of particular power and interest is Alternating Current (AC) Electrochemical Impedance Spectroscopy (EIS) which provides for the characterization of the electrical properties of many biological interfaces without biological destruction or interference.;The application of unique detection techniques of the latter, in this dissertation, resulted in high selectivity and sensitivity even with the presence of non-specific contaminants. Prior to this work, the measurement media was a liquid. However, a particularly formidable task has remained of detection of unlabeled antigens in air. EIS, a powerful technique for identifying electrode surface molecular reactions by measuring the electrical characteristics of the resultants over a frequency spectrum, was employed to detect impedance changes at the formation of an antibody-antigen conjugate. A new gel was developed capable of keeping antibodies active for extended periods of time, and also capturing antigens from the air. Another development was attaching the self-assembling monolayer, 3-MPTS (3-mercaptopropyl)trimethoxysilane, onto gold nanoparticles to create a unique active electrode.;The primary purpose of this dissertation work was to prove the concept of being able to capture a specific (to the antibody) antigen in the air, conjugate it with a specially coated non-dry electrode, and rapidly characterize the reaction with EIS. This work was the first to successfully accomplish this detection task utilizing a novel colloidal gold nanoparticle electrode, an active antibody, IgG, and a novel modified hydrogel. |
