New rhodamine B-based chromo-fluorogenic probes for highly selective detection of aluminium(iii) ions and their application in living cell imaging

Two rhodamine B-based fluorescent probes, BOS1 and BOS2, were designed and synthesized with good yields via the condensation reactions between the o-diaminobenzene modified rhodamine core structure (RBO) and salicylaldehyde derivatives. Both the probes exhibited remarkable absorbance-on and fluorescence-on responses to Al(3+) over other metal ions in ethanol–water (1 : 9, v/v) medium via the rhodamine ring-opening approach, which can be used for “naked-eye” Al(3+) detection over a broad pH range (5–9). The fluorescence intensities of the probes were linear with the Al(3+) ion concentration, resulting in a low limit of detection of 1.839 μM (BOS1) and 1.374 μM (BOS2) for Al(3+). In addition, the MTT assays and cell imaging experiments of Al(3+) in SGC-7901 living cells demonstrated that the probes had negligible cytotoxicity, and were cell permeable and suitable for sensing Al(3+) in biological systems.