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 photo-functional 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 non-volatile 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 towards 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.