An AIEE Active Anthracene-Based Nanoprobe for Zn²⁺ and Tyrosine Detection Validated by Bioimaging Studies

Abstract

Novel anthracene-based Schiff base derivative (4-(anthracen-9-ylmethylene) amino)-5-phenyl-4H-1,2,4-triazole-3-thiol; AT2) is synthesized and utilized as an aggregation-induced emission-enhancement (AIEE) active probe to detect Zn2+ and Tyrosine. Ultraviolet-visible absorption/photoluminescence (UV-vis/PL) spectroscopy studies on the AIEE property of AT2 (in ethanol) with increasing water fractions (fw: 0–97.5%) confirm the J-type aggregation. Excellent sensor selectivity of AT2 to Zn2+ and its reversibility with Tyrosine are demonstrated with PL interrogations. 2:1 and 1:1 stoichiometry and binding sites of AT2-Zn2+ and Tyrosine-Zn2+ complexes are elucidated from Job plots, HR-mass, and 1H-NMR results. Nanomolar-level detection limits (LODs) of Zn2+ (179 nM) and Tyrosine (667 nM) and association constants (Kas) of 2.28 × 10−6 M−2 (for AT2-Zn2+) and 1.39 × 10−7 M−1 (for Tyrosine-Zn2+) are determined from standard deviation and linear fittings. Nanofiber formation in AIEE and aggregated/dispersed nanoparticles in the presence of the Zn2+/Tyrosine are supported by scanning-electron microscope (SEM), transmission-electron microscope (TEM), atomic-force microscope (AFM), and dynamic-light scattering (DLS) investigations. Density-functional theory (DFT) studies confirm an “On-Off” twisted intramolecular charge transfer/photo-induced electron transfer (TICT/PET) and “On-Off-On” PET mechanisms for AIEE and sensors, respectively. B16-F10 cellular and zebrafish imaging are conducted to support the applications of AIEE and sensors.

Keywords

• nanoprobe
• AIEE
• anthracene
• Zn²⁺ detection
• reversible sensor
• tyrosine quantitation