Improving the optical response of chemosensors through the use of surfactant micelles

This review provides a comprehensive insight into recent (post-2020) examples of supramolecular micelles and their use in tandem with chemosensors/fluorophores to design and generate supramolecular-micelle-based sensing systems. Due to the broad range of surfactants available, the supramolecular micelles formed in these systems have both the ability to be tailored towards a specific analyte (metal cations with anionic surfactants, anions with cationic surfactants), and to work in tandem with the incorporated sensor system through encapsulation of the chemosensor and (or) through forming co-micellar aggregates. The examined supramolecular micelle-based sensing systems demonstrate an ability to enable functionality of previously non-responsive sensors, and (or) improve fluorescent/colorimetric responses, by providing stronger emissions and signal-to-noise clarity. A substantial portion of the reported work focuses on metal-ion based sensors working synergistically with anionic surfactants, with Hg²⁺ and Cu²⁺ ions as the most prominent analytes due to their well-known fluorescent quenching mechanisms. Cases involving Fe³⁺ and Cd²⁺ ions are also discussed within. Anion sensing is also a significant body of work covered in this review, with cationic surfactants assisting chemosensors for the detection of CN⁻, HS⁻, HSO₃⁻/SO₃²⁻ and NO₂⁻. In addition to ion-based sensors, recent small molecule and large macromolecule sensors are also reviewed within, with hydrophobic fluorophores encapsulated by a variety of supramolecular surfactant micelles.