A novel protein binding strategy for energy-transfer-based photoelectrochemical detection of enzymatic activity of botulinum neurotoxin A

In this work, we propose a novel energy-transfer-based photoelectrochemical (PEC) platform for probing of protein-protein interaction, which associates intimately with zinc-dependent cleavage and substrate specificities in the enzymatic activities of botulinum neurotoxin (BoNT). Specifically, by using substrate protein SNAP-25 as the energy-transfer nanoprobe, an exciton-plasmon interaction (EPI) based strategy between CdS quantum dots (QDs) and Au nanoparticles (NPs) in a PEC system is constructed with the photocurrent declining. Interestingly, the EPI effect is then interrupted by the target botulinum neurotoxin serotype A light chain (BoNT-LCA) special cleavage of the probe SNAP-25, leading to the photocurrent recovery. Therefore, the enzymatic activity of BoNT-LCA could be sensitively detected with a detection limit of 1 pg/mL. Unlike conventional DNA-programable assembly, a protein probe is used to bridge the excitons and plasmons in this work, which provides a new route for the investigation of the EPI-based bioassay.