Anthraquinone-metal complex fluorescence sensing platform for monitoring PPi mediated by Al3+ and bioimaging

Anions are widely found in humans and the environment. The analysis of its content and distribution shows great potential in the fields of life science, environmental science and biochemical reactions. Herein, a new anthraquinone derivative appended fluorescent probe (HBD) was developed as a reversible fluorescent probe for the detection pyrophosphate (PPi) in methanol/urotropine buffer medium (1:1, v/v, pH 4.5). The probe displayed fluorescence "turn-on" response towards Al3+ with high specificity. Due to the cleaving of the -C=N bond and subsequent creation of complex caused by coordination with Al3+, the chelation-enhanced fluorescence (CHEF) effect was activated, resulting in a significantly enhancement fluorescence response. Further, 1H NMR titration and HRMS analysis revealed that the Al3+ induced hydrolysis occurs on one side of the Schiff base and led to the formation of free primary amine compound. Moreover, the binding mechanism was also recognized density functional theory (DFT) studies. Due to the strong binding ability of PPi and Al3+, PPi could remove Al3+ from the complex, causing fluorescence quenching. The specific determination of Al3+ and PPi with the detecting limit of 31.6 nM and 56.8 nM. Due to its good biocompatibility, the sensor was successfully applied to fluorescence imaging of Al3+ and PPi in HeLa cells and zebrafish. The results show that HBD has broad application prospects in environmental and biological analysis.