A novel dimer-induced AIE material as a nano-sensor for colormetric and ratiometric sensing of Erythromycin and metal ions (Zn2+, Cd2+ and Cu2+) with different dissociation and re-aggregation processes and cellular imaging applications

Abstract

We reported a sensor BZH bearing AIE (aggregation-induced emission) characteristics in solid state and aqueous ethanol solution. In EtOH/H2O (1/9, V/V) medium, BZH possessed spherical shape with the average diameter of ~142 nm due to the unique dimer formation by intermolecular hydrogen bonds, and exhibited fluorescence ratiometric response to Erythromycin, Zn2+ and Cd2+ and UV–vis ratiometric behavior to Cu2+ along with remarkable naked-eye color changes, respectively. The binding stoichiometry of BZH to Erythromycin was 2:1, but that to metal ions was 1:1. The BZH towards Erythromycin and metal ions showed different sensing mechanisms, and were confirmed by job'plot, 1H NMR FT-IR, ESI-MS, DLS and TEM. The presence of Erythromycin triggered the ESIPT process and induced new intramolecular hydrogen bond formation, but the presence of metal ions (Zn2+, Cd2+ and Cu2+) caused deprotonation processes, these caused the BZH dimers' dissociation and consequently induced monomer emission. Meanwhile, the morphology of BZH changed from spherical to flower shape for Erythromycin and block shape for metal ions, indicating the Erythromycin and metal ions with BZH monomer further formed new aggregates, respectively. Furthermore, the BZH was applied to detect Erythromycin, Zn2+, Cd2+ and Cu2+ in actual water samples and Hela cells.