Effect of anions on fluorescence quenching of Rhodamine B–Pluronic F127 complex

Pluronic F127 has been widely used for controlled release of drugs. The aggregation behaviour and solubilisation properties of pluronics can be affected by addition of salts. This work reports the studies on the changes in micellar assemblies of F127 due to addition of inorganic anions (KCl, KBr, KI and KNO3) in Pluronic F127–Rhodamine B system. This was monitored by using UV–vis spectroscopy, fluorescence spectroscopy and fluorescence lifetime spectra. The change in fluorescence spectrum due to the presence of quenchers was attributed to the change in microenvironment of the micelle. The quenching depends on the ability of the fluorophore to transfer energy to the quencher. Out of all four salts, KI was observed to be the best quencher for the above system.