Localized surface plasmon resonance biosensing of Mycobacterium tuberculosis biomarker for TB diagnosis

Biosensors offer great advantages over conventional analytical techniques. Specifically, they can provide mul-tiple capabilities such as user-friendly operation, real-time analysis, rapid response, high sensitivity and speci-ficity, portability, label-free detection, and cost-effectiveness. As a result, this diagnostic approach is a point-of -care (POC) diagnostic and monitoring technology. In this study, for the first time, an optical biosensor chip was developed and analyzed using a localized surface plasmon resonance (LSPR) optical biosensing technique to monitor biomolecular interactions between mycolic acid TB antigen and anti -Mycobacterium tuberculosis anti-body. Mycolic acid was successfully immobilized on a gold-coated biosensor chip and allowed to react with anti -Mycobacterium tuberculosis antibody. To enhance the detection signal from biomolecular binding events, gold nanoparticles (AuNPs) were used and successfully bioconjugated with goat anti-rabbit IgG H&L secondary antibody and characterized using ultraviolet-visible (UV-vis) spectroscopy, dynamic light scattering (DLS), Fourier-transform infrared (FTIR) spectroscopy, and subsequently introduced on the biosensing layer. Scanning electron microscopy (SEM), energy-dispersive X-ray (EDX) spectroscopy, and atomic force microscopy (AFM) were used to characterize the biosensing surface. The optimized biosensor chip was analyzed using a custom-built biosensing transmission spectroscopy setup to perform LSPR biosensing. Our findings showed that mycolic acid was successfully immobilized on the biosensing surface and made it possible to capture anti -Mycobacterium tuberculosis antibodies. The LSPR optical biosensing technique was indeed successful in the detection of anti -Mycobacterium tuberculosis antibodies.