SSRN Electronic Journal | 2021
A Ratiometric Fluorescence Immunoassay for the Detection of C-Peptide
Abstract
We reported a platform for the reatiometric fluorescent sensing of C-peptide based on quantum dot-dylight (QD-DL) probe. Owing to the pre-built state of QD aggregation, there has been aggregation-enhanced fluorescence resonant energy transfer (AE-FRET) from a blue emissive QD aggregate donor to a red emissive DL acceptor in the internal of the QD-DL probe. The immune bridge between QD and DL was cleaved upon exposure to C-peptide through competition, resulting in termination of AE-FRET as the DL diffused away from QD. This results in QD emission enhancing and DL emission quenching. The resulting ratiometric response can be correlated quantitatively to the concentration of C-peptide, and was found to have a detection limit as low as 4.4 pM and rapid response time as short as 5 min. The potential for use in biological applications was demonstrated by measuring the response of the immunoassay into real serum samples. The methodology used here is built upon a highly multifunctional platform that offers numerous advantages such as low detection limit, enhanced photochemical stability, rapid sensing ability within a biological milieu.