A Selective Turn off Fluorescence Sensor Based on Propranolol-SDS Assemblies for Fe³⁺ Detection

A fluorophore modulation with sodium dodecyl sulphate (SDS) assemblies for the selective and sensitive sensing of Fe³⁺ ions in aqueous solution is illustrated in this work. Emission spectral characteristics of fluorescent molecule, propranolol (PPH) was intact in presence of metal ions. While on modulation with SDS assemblies, PPH was transformed into a tuneable sensor for Fe³⁺ ions. This sensor ensemble was not only highly sensitive towards Fe³⁺ ions in aqueous solution with detection limits lower than 3 μM but also possess high discriminating efficiency in presence of other metal ions like Cu²⁺, Pb²⁺, Zn²⁺, Ni²⁺, Fe²⁺, Cd²⁺, Co²⁺, Al³⁺, Mg²⁺, Hg²⁺ and Mn²⁺. The electrostatic interaction of the anionic group of surfactants with the metal cations significantly increases the communication between metal ions and PPH moiety which results in the quenching of PPH fluorescence. We have employed fluorescence steady state and lifetime studies to understand the metal sensing behaviour of the PPH-SDS sensor system. Principal component analysis (PCA) was used to evaluate the discriminative ability of the developed sensor system towards Fe³⁺ ions.