A Green Light Emitting Turn-on Ionic Liquid-based Nano-optode for Selective and Sensitive Detection of Dextran Sulphate

Abstract

Dextran sulfate sodium (DSS) is a polyanionic derivative of dextran, synthesized through the esterification of dextran with chlorosulfonic acid. DSS is a heparin-like polysaccharide; excessive use of DSS can lead to several adverse effects, including joint stiffness, pain, and hair loss. Therefore, developing a rapid and accurate method for the detection of DSS is essential for clinical diagnostics and treatment. Recently, the design of advanced photofunctional materials based on ionic liquids (ILs) has attracted significant attention due to their unique physicochemical properties, such as their ionic nature, low melting points, and nonvolatile behaviour, all while maintaining intrinsic photoluminescent functionality. In this study, we have strategically developed a fluorescent ionic liquid (FLIL) through a simple ionic exchange reaction. The resulting material exhibits high sensitivity and selectivity for the detection of DSS in both solid and liquid phases. The pure FLIL displays orange colour photoluminescence under a 365 nm portable UV lamp. When converted into water-suspended nanoparticles, nFLIL, the system shows a remarkable transition from non-fluorescent to green fluorescent upon the stepwise addition of DSS. The probe demonstrates excellent selectivity toward DSS with a limit of detection and quantification in the nanomolar range. In addition, a portable and user-friendly paper-based strip kit was developed, highlighting its potential for practical applicability of DSS detection in solid-phase samples. This work introduces an innovative approach for the development of DSS-sensitive, IL-based materials, offering superior properties over conventional systems for potential use in forensic and environmental monitoring.