Achieving highly sensitive detection of Cu²⁺ based on AIE and FRET strategy in aqueous solution

The aggregation-induced emission (AIE) luminogens are now showing strong potential in mimicking the energy donor of fluorescence resonance energy transfer (FRET) system. Herein, one highly efficient FRET system 1-NiR is successfully fabricated in aqueous solution based on an AIE active compound 1 and fluorescence dyes (Nile red (NiR)). 1 acts as the energy donor and NiR acts as the acceptor in the FRET system with the optimum concentrations ratio [1]/[NiR] = 100. Besides, the AIE(1) itself displays excellent selectivity for Cu²⁺ ions at 525 nm with the detection limit of 1.32 × 10^-7 M. While through the FRET system of 1-NiR system, the detection limit of Cu²⁺ can be further decreased to 9.12 nM by monitoring the fluorescence at 630 nm. As a result, using an AIE probe to detect Cu²⁺ based on FRET mechanism is a promising strategy.