Construction of a ratiometric turn-on fluorescent probe based on amino acid skeleton for specific detection of Al3+ ions in environmental and biological system

In this work, a novel colorimetric and fluorometric dual-channel fluorescent sensor NHO based on an unsaturated amino acid derivative was rationally designed. The sensor exhibited discerning and expeditious fluorescence sensing capabilities towards Al³⁺ in MeOH/Hepes buffer solution (9/1, v/v, pH 7.4). The fluorescence of NHO at 537 nm was significantly and instantaneously enhanced upon addition of Al³⁺ ions, and this fluorescence could be reversibly quenched by EDTA. The detection limit (LOD) and binding constant of NHO for Al³⁺ were determined to be 24.8 nM and 6.1 x 10⁹ M⁻², respectively. The mechanism of interaction between NHO and Al³⁺ was comprehensively investigated and theoretically supported via DFT calculation. Furthermore, NHO’s multifaceted practical applications in detecting Al³⁺ ions were explored, including tests in real water samples, commercially available almagate suspension and applications on test paper. A smartphone-assisted detection platform was developed, making the monitoring of Al³⁺ ions more convenient and cost-effective. Additionally, NHO also exhibited promising bioimaging capabilities in PK-15 cells. These inventions highlighted that NHO was a useful tool for the detection of Al³⁺ in both environmental and living systems.