Ultrasensitive detection and high-contrast bioimaging of Hg2+ using monothiosquaraine-based fluorescent probe via hydrogen bond promoted desulfurization

• Published in: Microchemical journal Vol. 179; p. 107481
• Main Authors: Wang, Guimei, Xu, Wenjian, Liu, Yunfan, Fu, Nanyan
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.08.2022
• Subjects: Fluorescent probe; Hg2+ detection; High contrast bioimaging; Hydrogen bond promoted desulfurization; Monothiosquaraine; Monothiosquaraine; Hydrogen bond promoted desulfurization; High contrast bioimaging; Hg2+ detection; Fluorescent probe
• ISSN: 0026-265X; 1095-9149
• DOI: 10.1016/j.microc.2022.107481

[Display omitted] •Two monothiosquaraine based fluorescent probes of Hg2+ have been constructed.•Hydrogen bonding assisted Hg2+-specific desulfurization has been used in Hg2+ sensing.•The fluorescent probes show excellent selectivity and high sensitivity.•They have been applied in environmental samples and high contrast living cell imaging.•The sensing mechanism has been discussed. Mercury (Hg) is an exceedingly toxic heavy metal which leads to grievous nonbiodegradable contamination and human health threat. Thus, developing a practical, quick, effective and labor-saving method for detecting Hg2+ is of great significance. In this study, we rationally design two novel near-infrared (NIR) monothiosquaraine-based probes MTSQ-1 and MTSQ-2 for tracking and bioimaging of Hg2+ with the mercury-desulfurization strategy. MTSQ-1 and MTSQ-2 show ultrahigh sensitivity, superb selectivity and rapid response for spotting of Hg2+ in vitro. We find that it is the intramolecular hydrogen bond between the carbonyl oxygen of the squaraine core and the ortho-hydroxyl substituent of the anilinyl moiety that promotes the desulfurization of the probes, inducing enhanced fluorescence emission. Related sensing mechanism has been fully discussed through experimental methods and theoretical calculations. Meanwhile, MTSQ-1 has been used in detection of Hg2+ in river samples, and MTSQ-2 encapsulated in β-CD possesses good ability for imaging of Hg2+ in HeLa cells with high signal-to-background ratio.