Gravimetric Detection of Pathogens and an Electrochemical Study of the Immunological Consequences of Tuberculosis Exposure

Abstract

The continual spread of diseases, such as tuberculosis and influenza, which primarily affect poverty-stricken areas, could be slowed if suitable diagnostic resources were to become available. This dissertation examines the challenges of combining immunological detection with inexpensive technologies to pave the way for accessible diagnostic devices. The equilibrium association constants of multiple antibodies with Mycobacterium tuberculosis or an antigenic component of the cell wall, lipoarabinomannan, were compared using the quartz crystal microbalance. By establishing the kinetics governing these interactions, it was determined which antibodies promote the most sensitive method for the detection of tuberculosis. Similarly, the hemagglutinin protein of an H5N1 influenza virus was detected with an immunosensor and the kinetics of the achieved binding were examined. The immunosensor was calibrated with multifunctional gold nanoparticle simulants to provide for a safe and effective means of calibration at the point of care. With the development of these new sensors, steps have been made to address the lack of analytical techniques suitable for incorporation into low-resource environments. In addition to the detection of pathogens, it is important to further the understanding of the immunogical consequences of tuberculosis exposure. Mycobacterium tuberculosis can remain dormant until such a time when the infected individual becomes immunocompromised. To understand how tuberculosis can evade the normal cellular defense mechanisms, a new sensor was developed to study macrophage immune response. An electrode for the detection of superoxide, a reactive product released when white blood cells undergo oxidative stress, was developed and characterized. A microfluidic environment capable of housing this new sensor was developed that can continuously monitor the production of superoxide in real-time. The work outlined in this dissertation improves electrochemical studies of oxidative response, makes critical improvements in tuberculosis and influenza detection, and is essential to the understanding of macrophage response to a foreign pathogen.