| Surface plasmon resonance (SPR) based biosensors have become a central analytical tool in the quantification of disease-representing biomarkers in biological fluids. However, conventional SPR detection systems are bulky, sophisticated and expensive, rendering them unsuitable for point-of-care applications. In this study, biofunctional nano-biosensors based on gold nanorods in solution and those immobilized on glass slides are developed for rapid and onsite monitoring of biomolecules. Specifically, I propose to develop a point-of-care, nanobiosensing system to rapidly quantify the level of cardiac troponin I (cTnI) in plasma samples for heart attack diagnosis. A label-free mode of detection is obtained through localized surface plasmon resonance (SPR) by gold nanorods. Gold nanorods possess strong optical absorption spectra at visible and near-infrared region due to SPR property. By adjusting the aspect ratio of the nanorods, one can easily tune the characteristic absorption spectra to enable label-free, multiplex detection in a single sample. Here, we synthesized gold nanorods of various aspect ratios (e.g. 5-20) and characterized the nanoparticles using electron microscopy and spectroscopy. The gold nanorods were then biofunctionalized using various immobilization methods for specific cTnI quantifications. Upon binding of target cTnI molecules, the nanorod biosensor was quantified by the shifting magnitude of the longitudinal SPR peak. Magnetic nanoparticles was found to significantly enhance the nanoSPR biosensor sensitivity to enable cTnI quantifications in the clinical relevant ranges. |
