Pyrene-Based Fluorescent Probe for “Off-on-Off” Sequential Detection of Cu2+ and CN− with HeLa Cells Imaging

• Published in: Chemosensors Vol. 11; no. 2; p. 115
• Main Authors: Shellaiah, Muthaiah, Venkatesan, Parthiban, Thirumalaivasan, Natesan, Wu, Shu-Pao, Sun, Kien-Wen
• Format: Journal Article
• Language: English
• Published: Basel MDPI AG 01.02.2023
• Subjects: aggregation-induced emissions; Aqueous solutions; biocompatibility; Carbon dioxide; Cell culture; chemosensor; Copper; copper ion; cyanide ion; Cytotoxicity; Density functional theory; Emissions; Ethanol; Excimers; Fluorescent indicators; Imines; NMR; Nuclear magnetic resonance; Photoluminescence; Photons; Pyrene; pyrene derivative sequential detection; Stoichiometry; Titration; Toxicity
• ISSN: 2227-9040; 2227-9040
• DOI: 10.3390/chemosensors11020115

The novel pyrene-appended Schiff base probe L with aggregation-induced emissions (AIE) relevant to an increase in water fractions (0–90%) is synthesized and applied in sequentially detecting Cu2+ and CN−. The pyrene-based probe L firstly induces the excimer formation in the presence of Cu2+. However, the process can be reversed by sequentially adding CN−, which is demonstrated using the fluorescence “Off-On-Off” response in semi-aqueous media ethanol water (v/v = 7/3) under physiological pH (5 mM HEPES, pH 7.0). The Job’s plot, mass analysis, 1H NMR titrations, and density functional theory (DFT) interrogations confirm the 2:1 stoichiometry of excimer complex L–Cu2+-L*, preferential binding atoms, and CN− tuned complex reversibility. Based on the photoluminescence (PL) titration, the association constant of L to Cu2+ is determined as 4.95 × 106 M−1. From standard deviation and linear fittings, the detection limits (LODs) of Cu2+ and CN− are estimated as 219 nM and 580 nM, respectively. The practicality of Cu2+ and CN− detection is demonstrated using a TLC plate and a blended polymer membrane through which significant color changes under a UV lamp can be monitored. Moreover, utility of the designed probe L towards biological application with low toxicity is demonstrated by detecting Cu2+ and CN− inside HeLa cells. The responses of the probe to Cu(II) ions were also verified using living HeLa cells imaging.