Heparin Gold Nanoparticles as a Colorimetric Probe for Cardiac Troponin I Detection

Abstract We report a simple, visual detection strategy for cardiac biomarker, troponin I (cTnI), a promising indicator of cardiac disease based on heparin gold nanoparticles (HAuNPs). The red shift in the plasmon absorption band followed by color change of the solution is the basic principle of the assay. The observed red shift and color change were attributed to the strong electrostatic attraction between the glycoaminoglycans and heparin binding groups present in cTnI. The method exhibits linearity between cTnI concentration and corresponding absorbance in the range of 0.5–20 ng/mL with a detection limit of 0.3 ng/mL. Other major blood proteins did not show any interference, and the binding was found to be pH dependent. The antibody free method was successfully applied to the quantification of cTnI in human serum and showed good correlation with the hospital measurements. Thus, HAuNPs-based assay is a quick, label-free platform for cTnI detection.