The development of a hand-held, self-powering bio-sensing device for the early detection of mycobacterium tuberculosis

[摘要] ENGLISH ABSTRACT: Tuberculosis (TB) has been described as one of the top 10 leading infectious and deadliest diseases in the world and millions of people still contract and die from TB each year. TB diagnosis serves as one of the most important aspects towards controlling and ending TB. The current methods of testing for TB infection are very expensive and non-portable, laboratory-based, require experienced personnel, sometimes with poor accuracy and lack the ability to generate same-day results at point-of-care. Hence, the time from diagnosis to treatment is unnecessarily prolonged.This project presents the fabrication of a low-cost, portable, electronic biosensor for the early detection of Tuberculosis. A biotin-modified probe was linked using the non-covalent interaction of streptavidin-biotin and immobilised onZinc Oxide (ZnO) nanosensor. Streptavidin and biotin immobilisation was studied and confirmed using a Fourier Transform Infrared (FTIR). The ZnOnanowires were grown and optimized using the electrochemical deposition technique, which helped to improve the c-axis alignment of the nanowires.The ZnO nanowires were characterized using a scanning electron microscopy (SEM). Probe immobilisation was studied and confirmed using an atomic forcemicroscopy (AFM) and the piezoelectric response of the nanosensor itself. The high affinity of the biotinylated-probe, immobilised on the nanosensor surface,to the target molecule, resulted in a direct piezoelectric effect, meaning the increase in the concentration and binding of the target molecule caused the measured output piezoelectric voltage of the nanowires due to the high degreeof bending of the nanowires. Electronic circuits were simulated and built for an easy and inexpensive way to measure the piezoelectric voltage fromthe nanosensor, without having to use expensive equipment. The electronic circuit was successfully used to measure the piezoelectric voltage from the nanosensor. The biosensor was successfully fabricated and tested as a proof ofconcept, the chosen biotin-probe was the anti-luteinizing hormone-ß to detect the luteinizing hormone present in our bloodstream. An increase in piezoelectricpotential were due to an increase in antibodies concentration bound to the sensor surface, and this evidence shows that the ZnO nanosensor may be used to record changes in antibody concentrations. The recorded concentrations ofthe anti-luteinizing hormone-ß were ranging from 25 to 10 ng/µl.

[发布机构] Stellenbosch University