Polyethyleneimine-induced fluorescence enhancement strategy for AIEgen: the mechanism and application

Aggregation-induced emission luminogens (AIEgens) are attracting extensive research attention in the biosensor fields. Herein, we report a new polyethyleneimine (PEI)-induced strategy for enhancing luminescence of TCBPE (an AIEgen) to promote its development in biosensor. The copolymer dots (TCBPE-PEI) with high quantum yield (39.7%) and outstanding stability were synthesized via a one-pot method. The fluorescence enhancement mechanism based on the PEI strategy originated from the restriction of intramolecular motions of TCBPEs and the form of donor–acceptor structures to decrease the inherent energy bandgap. Benefiting from chelating property of TCBPE-PEI by Cu, a fluorescence-quenching sensor for Cu detection was developed based on the fluorescence quenching of the electron transfer effect. Especially, a good linear range of 10–250 nM with a low limit of detection 1.1 nM was achieved, and it was further applied in samples successfully. The current work provides a novel approach to fabricate AIEgen biosensors and shows great potential in Cu detection. Graphical Abstract: [Figure not available: see fulltext.].