Stimuli-responsive discriminative detection of Cu2+ and Hg2+ with concurrent sensing of S2- from aqueous medium and bio-fluids by C N fused azophenine functionalized “smart” hydrogel assay @A potential biomarker sensor for Wilson’s disease

Abstract

• Azophenine based colorimetric chemosensor, CN-1 is synthesized by solvent-free FeCl 3 mediated C N bond fusion pathway. • CN-1 can selectively and discriminatively detect aqueous Cu 2+ , Hg 2+ with LOD of 30 and 480 ppb respectively. • The reversible sensing by S 2− could formulate “Write-Read-Erase-Read” memory element and 4-input complex logic circuitry. • CN-1 can successfully detect Cu 2+ & Hg 2+ in real water samples with qualified recoveries by functionalized hydrogel assay. • The detection ability of unbound Cu 2+ from bio-fluids made it a potential diagnostic tool for monitoring Wilson’s disease. A multi-functional azophenine based colorimetric chemosensor, CN-1 has been reported by catalytic FeCl 3 mediated facile oxidative C N bond fusion of o -anisidine. The chemosensor, characterized by single crystal X-ray crystallography, can be exploited towards ‘naked-eye’ discriminative detection of Cu 2+ and Hg 2+ (LOD = 30 and 480 ppb respectively) from purely aqueous medium through colorimetric and electrochemical (CV) readouts. It is equally responsive towards intoxicated real water specimen, like river water, industrial sewage water, demonstrating its practical applicability. Along with detection, CN-1 exhibited metal ion sequestration capability, leading to the removal of ∼74 % and ∼40 % removal of Cu 2+ and Hg 2+ respectively from contaminated water bodies. Moreover, the unprecedented uniqueness of the synthesized azophenine based chemosensor levies in its capability towards ppb level Cu 2+ detection colorimetrically from target-specific bio-fluids to monitor aberrant unbound copper levels, thereby highlighting it as a potential biomarker sensor as well as a pathological non-invasive diagnostic tool of Wilson’s disease , which has been explored for the first time in the domain of azophenine based host-guest chemistry. The reversible spectrochemical response in presence of aqueous S 2− could efficiently formulate “ Write-Read-Erase-Read ” nature of a memory element and four-input complex logic circuitry for molecular level information storage, which is also hitherto unexplored in the azophenine family. One step ahead, fabrication of functionalized “smart” hydrogel assay escalates the reliability and practical applicability of the present work through simple ‘naked eye’ colorimetric-optical readouts.