Wavelength modulation based surface plasmon resonance sensor for detection of cardiac marker proteins troponin I and troponin T

A wavelength modulation based surface plasmon resonance (SPR) sensor setup was developed with inexpensive components. The developed setup is utilized for the detection of cardiac marker proteins, cardiac troponin I (CTnI), and cardiac troponin T (CTnT). A simple approach was used for the fabrication of CTnI/CTnT antibody sensor chip. A self-assembled monolayer (SAM) of 1-octanethiol and 11-mercaptoundecanoic acid (11-MUA) was formed on annealed Au thin film. The −COOH group of 11-MUA was modified with EDC-NHS for amine coupling to monoclonal antibodies of CTnI and CTnT. The developed SPR setup and the sensor chip with monoclonal antibodies showed good performance for the detection of CTnI and CTnT in direct assay. For CTnI, the lowest concentration detected was 0.03125 ng/mL whereas for CTnT, it was 0.0625 μg/mL. The detected concentrations are well below the onset concentration of these two proteins in blood following the acute myocardial infarction (AMI). The performance of this direct assay based on the developed setup and sensor chip therefore can be used easily for detection of CTnI and CTnT during their onset period.