Digital Plasmonic Immunosorbent Assay for Dynamic Imaging Detection of Protein Binding

Abstract A highly sensitive imaging sensor and digital plasma immunosorbent assay, based on a gold-titanium plasmonic nanopore array, has been reported. The sensor can quantitatively determine a low concentration of proteins and exhibits superior performance by combining a classical Poisson statistical algorithm and the digital surface plasmon resonance (SPR) imaging technique. In this study, we used a device to detect C-reactive protein (CRP) and anti-CRP antibody binding information from SPR images. Our technique avoids complex spectroscopic detection and was applied to detect the inflammatory marker CRP protein with an LOD of 2.36 ng/ml using white light. Moreover, we analyzed the protein-binding kinetics and demonstrated that our device could also be used to determine the equilibrium dissociation constant in protein interactions through ultrasensitive dynamic imaging of the CRP protein during interaction with anti-CRP antibodies. Owing to the superior performance of the plasmonic nanopore array, the proposed device is promising for future portable optical sensing with visible light for the early detection of diseases.