Fluorescence correlation spectroscopy using octadecylrhodamine B as a specific micelle-binding fluorescent tag;: Light scattering and tapping mode atomic force microscopy studies of amphiphilic water-soluble block copolymer micelles

Amphiphilic multimolecular block copolymer micelles of polystyrene-block-poly(methacrylic acid) and polystyrene-block-poly(ethylene oxide) were investigated by fluorescence correlation spectroscopy (FCS) in aqueous media using octadecylrhodamine B (ORB) as a micelle-specific probe, together with UV-visible absorption and other fluorescence techniques (steady-state spectroscopy and depolarization and time-resolved fluorescence decay measurements). The aim of the study was to show that the fluorescence techniques alone provide sufficient information on the micellar system, allowing, thus, for the fully conclusive study. Other techniques, such as static and quasi-elastic light scattering and atomic force microscopy were used just for comparison to prove the reliability of the FCS results and estimate their accuracy. The binding kinetics of ORB to micelles in aqueous solutions accompanied by association-dependent changes in UV-vis and fluorescence spectra and the binding equilibrium were also studied because knowledge of them is necessary for the correct interpretation of the FCS results.