| Description |
Currently, all over the world, a lot of money is being pumped into the healthcare domain to facilitate development of rapid, point-of-care disease diagnostic platforms, which are relatively cheap with enhanced ease-of-use capabilities that can be deployed in low-resource settings which have higher prevalence of disease infected cases. Volatile organic compounds (VOCs) represent one class of biomarkers that has been less explored but possesses immense potential from a disease diagnostic standpoint. Tuberculosis (TB) has been a cause of significant health concern affecting a large population of people in Africa and Asia and recently, researchers have identified four specific TB VOCs from the breath of infected patients, through GC-MS analysis techniques. Rapid, accurate diagnosis is critical for timely initiation of treatment and, ultimately, control of the disease. Lack of access to appropriate diagnostic tools is caused, in part, by shortcomings as currently available diagnostics are often ill-adapted to resource-limited settings or specific patient needs, or may be priced out of reach. Although many countries still rely on basic tools such as smear microscopy, new diagnostics are changing the TB diagnostics landscape. Some groups have previously attempted to develop breath-based TB detection techniques utilizing evanescent wave technology and colorimetry-based pattern detection techniques, but no sensors exist for detection of the four methyl ester-based VOCs. In the research presented in this dissertation, we have attempted to develop a low-cost, metal functionalized titania nanotubular array-based sensor platform for electrochemical detection of the four major TB volatile organic biomarkers (VOBs). TiO2 or titania nanotubes is an easy-to-synthesize, robust, wide bandgap (~3.2 eV) semiconductor material with excellent vectorial charge transport properties. In addition, the nanotubular morphology presents a large surface-area-to-volume ratio with sufficient metal bound active sites which facilitates efficient binding with the VOBs of interest. Titania nanotubes with an optimized morphology and stoichiometry and functionalized with cobalt through the incipient wetting impregnation, and an in-situ lattice functionalization method for electrochemical detection of the four TB VOBs and their subsequent integration into a sensor hardware, has been investigated. The potential light assisted, plasmonic-based sensing capabilities of gold nanoparticle functionalized TiO2 nanotubes have been illustrated as well. In the end, a similar but slightly tweaked sensing platform has been tested for the detection of nonpulmonary colorectal cancer as well, extending the detection capabilities of the fabricated sensor substrate and leaving room for further research for screening of other life-threatening diseases. Improved access to better TB screening and diagnostics may present potential opportunities that may include efforts to accelerate market entry and/or scale-up of the innovative sensing platform that addresses unmet needs. |
