A novel "turn on" fluorescence probe based on a caffeic acid skeleton for detecting Al 3+ and bioimaging application.

The specificity detection of Al 3+ is important for monitoring life health and environmental pollution. A fluorescence enhancement probe based on caffeic acid HAM was synthesized for detecting Al 3+ with high sensitivity and good selectivity. When Al 3+ was added in the aqueous solution of HAM, the formation of HAM-Al 3+ complexes inhibited the PET process, which led to great enhancement of fluorescence. The addition of other metal ions cannot induce the change of fluorescence intensity. The sensing mechanism was proved by 1 H NMR titration, MS, and Job's plot. Moreover, probe HAM exhibited excellent properties, such as high sensitivity (LOD = 0.168 μM), fast response time (30 s), wide pH range (3-11), and good interference ability. Based on the above results, probe HAM was used to explore its bioimaging application in biological samples.