A novel fluorescent probe for Cr3+ based on rhodamine-crown ether conjugate and its application to drinking water examination and bioimaging

A trivalent chromium (Cr3+) fluorescence probe (RhC) was designed and synthesized via Schiff base reaction based on rhodamine-crown ether conjugate. This probe displayed a favorable selectivity for Cr3+ over a range of other common metal ions in DMF/H2O (3:7, v/v; PBS buffer 50 mmol L-1; pH = 6.8) solution, leading to prominent fluorescence OFF-ON switching of the rhodamine fluorophore. The limit of detection was calculated to be 15 mu mol L-1 (S/N = 3). The binding ratio of RhC-Cr3+ complex was determined to be 1:2 according to the Job's plot and HR-MS. The probe was successfully applied to examination of Cr3+ in drinking water spiked samples. The average recoveries ranged from 104.9% to 106.9% at spiked concentration level of 10.00 mu mol L-1, and the obtained results were consistent with those obtained using atomic absorption spectrometry (AAS). Moreover, bioimaging experiments showed that RhC can sense the Cr3+ in living cells with a fluorescence enhancement signal. (c) 2015 Elsevier B.V. All rights reserved.