| Summary: | Early diagnosis of Mycobacterium tuberculosis is very important to reduce the number of fatal cases and allow fast recovery. This can be done by using smear microscopy method; however, the interpretation of results requires skilled personnel due to tendency of the method to produce false-negative results (lack of sensitivity). Therefore, in this study, sandwich-type electrochemical immunosensor and aptasensor were compared for detection of CFP10-ESAT6 complex antigen as a biomarker of Mycobacterium tuberculosis, based on graphene/polyaniline (GP/PANI) modified screen-printed gold electrode (SPGE). GP/PANI nanocomposite was synthesized and characterized using Raman spectroscopy and Field Emission Scanning Electron Microscope (FESEM) in order to confirm the formation of nanocomposite. Then, it was dispersed in 3-aminopropyltriethoxysilane (APTES) and used as an electrode modifier. The morphology of the fabricated GP/PANI-SPGE was analyzed using FESEM and it showed a rough and porous surface while Energy Dispersive X-ray (EDX) spectroscopy has shown all the presence elements of GP/PANI on SPGE surface. Based on cyclic voltammetry (CV) characterization, the fabricated GP/PANI-SPGE has shown a large surface area compared to unmodified electrode. Capturing probes (antiCFP10-ESAT6 antibodies or aptamer) were immobilized onto the surface of GP/PANI-SPGE. Iron/gold magnetic nanoparticles (Fe3Q4/Au MNPs) conjugated with anti-CFP10-ESAT6 was used to complete the sandwich system. The Fe3Q4/Au MNPs was synthesized and characterized using Ultraviolet-Visible (UV-Vis) spectrophotometer, High Resolution-Transmission Electron Microscopy (HR-TEM) and X-ray Diffraction (XRD) before conjugating it with anti-CFP10-ESAT6. Differential pulse voltammetry (DPV) technique was used to investigate the analytical performance of both immunosensor and aptasensor with its corresponding CFP10-ESAT6 antigen. The detection time was within 2 hours. Under optimum conditions, both sensors showed comparable results with almost the same limit of detection (LOO) of 1.47 ng/ml for immunosensor and 1.52 ng/ml for aptasensor. However, aptasensor showed better specificity and reproducibility than immunosensor. The methods developed from these processes were then integrated into a portable reader, which provides a good correlation with conventional methods on detection of M. tuberculosis in sputum samples. Henceforth, the developed biosensor
demonstrated potential as a practical screening tool for M. tuberculosis detection.
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