A novel reversible fluorescent probe for sequential detection of Al3+ and HPO42− based on caffeic acid and its applicability in cell imaging

In this work, we focused on synthesizing a new fluorescent probe HBA based on caffeic acid for detecting Al 3+ /HPO 4 2− by the mode of “off-on-off”. HBA alone exhibited a weak fluorescence emission in aqueous solution. When Al 3+ was added into the HBA solution, a significant green fluorescence was found at 498 nm. However, the introduction of HPO 4 2− to the solution of [ HBA -Al 3+ ] complex induced the disappearance of green fluorescence. The detection limit of HBA was calculated as low as 41.7 nM for Al 3+ and 62.1 nM for HPO 4 2− , respectively. Probe HBA exhibited good cell-membrane penetrability and had the potential to trace Al 3+ /HPO 4 2− in biological systems.