RNA aptamer-based optical nanostructured sensor for highly sensitive and label-free detection of antigen–antibody reactions

Developments of optical protein sensors with nanostructure based on the noble metals have currently received great attention for their high efficiency and simultaneous analysis of various important biomolecules from proteomics to genetics. In this study, we exploited the absorbance spectra of gold-capped nanoparticles substrate for label-free detections of antigen–antibody reactions using a specific thiolated RNA aptamer. These synthesized RNA aptamers have been optimized to bind to the Fc portion of the human IgG1 subclass, due to their ability to orient antibodies direction on the gold surface. After attaching the anti-fibrinogen antibodies on the surface via these linkers, our thiolated RNA aptamer-based nanostructured sensors were easily applicable to specific detections of fibrinogen with a limit of detection of 0.1 ng/mL. These nanostructured sensor-based models will open a way to display numerous immunosensors as well as to develop other functionally similar sensors which could then be expanded into multi-arrays assay systems.