A novel aptamer biosensor based on polydopamine quenched electrochemiluminescence of polyfluorene nanoparticles for amyloid-β oligomers detection

Alzheimer’s disease (AD), as a serious neurodegenerative disease, has posed a great threat to human health. Sensitive detection of its specific biomarker amyloid-β oligomers (AβO) is very important. This work developed a novel electrochemiluminescence (ECL) biosensor for detecting AβO with poly [(9,9-dioctyl-fluorenyl-2,7-diacyl)-alt-co-(9-hexyl-3,6-carbazole)] nanoparticles (PFA NPs) as luminophore and polydopamine (PDA) as ECL quencher. The PFA NPs prepared with poly (styrene-co-maleicanhydride) (PSMA) as carboxyl functionalization reagent were found to have strong ECL emission at + 1.25 V with tripropylamine (TPrA) as coreactant. Furthermore, PFA NPs exhibited charming ECL stability and their ECL signals remained almost unchanged even after a year of storage. The rich carboxyl functional groups on the surface of PFA NPs facilitated the covalent bonding of biomolecules, thus facilitating the construction of “signal-on” ECL aptamer biosensor for detecting AβO. Meanwhile, target switching strategy coupling with three-dimensional (3D) DNA walker cycle amplification endowed aptamer biosensor with excellent analytical performance, characterized by low detection limit (8.30 × 10−15 M) and wide detection range (1.00 × 10−14~1.00 × 10−9 M). This work explored the application of PFA NPs in ECL filed and coupled excellent ECL performance of PFA NPs, efficient ECL quenching effect of PDA, and high sensitivity of target switching strategy for ultrasensitive detection of AβO.