Development of nanobiosensors for phenolic endocrine disrupting compounds and anti- tuberculosis drugs

>Magister Scientiae - MScTuberculosis still remains one of the world’s killer diseases. Pyrazinamide (PZA) is one of the most commonly prescribed anti-tuberculosis (anti-TB) drugs due to its ability to significantly shorten the TB treatment period. However, excess PZA in the body caused hepatotoxicity and liver damage. This, together with the resistance of the bacteria to treatment drugs, poor medication and inappropriate dosing, contribute significantly to the high incidents of TB deaths and diseases (such as liver damage). This, therefore, calls for new methods for ensuring reliable dosing of the drug, which will differ from person to person due to inter-individual differences in drug metabolism. A novel biosensor system for monitoring the metabolism of PZA was prepared with a nanocomposite of multi-walled carbon nanotubes (MWCNTs), polyaniline (PANI) and cytochrome P450 2E1 (CYP2E1) electrochemically deposited on a glassy carbon electrode (GCE). The nanocomposite biosensor system exhibited enhanced electro-activity that is attributed to the catalytic effect of the incorporated MWCNTs. The biosensor had a sensitivity of 7.80 μA/ μg mL-1 PZA and a dynamic linear range (DLR) of 4.92 – 160 ng/mL PZA. Bisphenol A (BPA) is a hormone-disrupting chemical used in production of epoxy resins and polycarbonates, which produce various products used on a daily basis. However, BPA can leach out of plastic during normal use and cause health effects such as cancer or disrupt the endocrine system. Moreover, BPA has also been proven to degrade from the containers in landfills and accumulate in groundwater and streams, thereby, polluting the environment while destroying aquatic organisms. Therefore, this also calls for new selective and sensitive methods for the monitoring of BPA. A novel biosensor system for monitoring the oxidation of BPA was prepared from a nanocomposite of polyaniline, polymethyl methacrylate and titanium dioxide nanoparticles, also electrochemically deposited on the GCE. Biosensor fabrication was conducted by immobilization of the enzyme manganese peroxidase (MnP) iii onto the nanocomposite film. The nanobiosensor also revealed enhanced electro activity, attributed to the incorporation of TiO2 nanoparticles. The biosensor system had a sensitivity of 0.3 μA/nM and a detection limit of 0.12 nM. This detection limit falls within the range of the allowed daily intake of BPA as recommended by the Food and Drug Administration (FDA, USA) and other regulatory bodies