A novel FRET immunosensor for rapid and sensitive detection of dicofol based on bimetallic nanoclusters

Abstract

To minimize the need of complex testing procedures, accurate, rapid and selective on-site determination of dicofol (DICO) is of vital importance. Herein, fluorescence immunosensing platforms based on the Förster resonance energy transfer (FRET) between Au–Ag bimetallic nanoclusters (Au–Ag NCs) and Au nanoflowers (Au NFs) were developed for the rapid detection of DICO in both liquid system and paper-based analytical devices (PADs). Conjugations of Au–Ag NCs and antigen (NCs-Agen) and Au–Ag NCs were regarded as energy donors in liquid system and PADs, respectively, while conjugations of Au NFs and antibody (NFs-Ab) were synthesized as energy acceptors. The overlapping spectrum and decrease of fluorescence lifetime of NCs-Agen proved that the fluorescence quenching mechanism was FRET effect. When DICO was captured by NFs-Ab, FRET effect was inhibited due to the long distance between NFs-Ab and NCs/NCs-Agen. Under optimal conditions, the FRET-based fluorescent immunosensors allowed for a rapid response toward DICO with considerable sensitivities of 0.185 ng/mL and 0.170 ng/mL in liquid system and PADs, respectively. Excellent specificity and satisfactory recovery in three kinds of tea samples were confirmed as well. This study opens an avenue for on-site, portable and sensitive detection methods.