Abstract

Plasmonic chip with a wavelength-size periodic structure can provide the enhanced electric field on the chip surface and therefore, in the fluorescence detection and imaging, the target molecule was sensitively detected with the sandwich immunoassay by the larger fluorescence signal. Here, the hole array-type and Bull's eye-type patterns were used for target detection of S-protein and single exosome, respectively. The capture interface was prepared for suppressing the nonspecific adsorption of labeled-antibody and detection antibody was also considered. The fluorescence was measured with an angle scanning system and a fluorescence microscope. S-protein was detected at 0.1 ng/mL within 40 min. On the other hand, single exosome modified with some kinds of labeled-antibody was detected at the exosome concentration of 47 fM. The combination of the S-protein immunoassay and single exosome detection and analysis method can be applied to detection of SARS-CoV-2 virus.

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