Al3+ induced hydrolysis of anthraquinone-based Schiff base fluorescent probe for determination PPi ions and bioimaging

Abstract

Herein, a novel anthraquinone derivative appended fluorescent probe (HAD), has been developed as a reversible probe for detection of aluminium ions (Al3+) and pyrophosphate (PPi) in buffer medium. The probe displays fluorescence “turn-on” response towards Al3+ with high specificity. The activation of the chelation-enhanced fluorescence (CHEF) effect occurs as a consequence of the formation of a complex via coordination with Al3+, which was due to the imine bond is dynamic and reversible and further causing subsequent cleavage of the -C=N bond in the presence of Al3+. This complex significantly amplifies the fluorescence response. Additionally, according to the Job's plot and high-resolution mass spectrometry (HRMS) measurements, the binding stoichiometry of HAD and Al3+ ions is 1:2. Moreover, Density functional theory (DFT) investigations further elucidate the binding mechanism. The original spectrum is restored after the addition of PPi, which is due to the formation of more stable Al3+-PPi complex. The specific determination of Al3+ and PPi with the detecting limit of 47.6 nM and 73.7 nM (S/N = 3), respectively. Due to its exceptional biocompatibility, the probe has facilitated the development of Al3+ and PPi imaging in vitro and in vivo, thereby showcasing its remarkable capabilities in the realm of environmental and biological analysis.