A surfactant type fluorescence probe for detecting micellar growth

We report on the detection of micellar growth in anionic, cationic, and catanionic surfactant systems using a novel surfactant type fluorescence probe, sodium 12-(N-dansyl)amino-dodecanate (12-DAN-ADA). The fluorescent group was incorporated in the tail of the surfactant which tethers the fluorescent group deep inside the apolar micellar cores. The fluorescence anisotropy of 12-DAN-ADA was found to be very sensitive for directly detecting the micellar growth in micelles containing oppositely charged surfactants, including cationic CTAB systems and mixed systems of oppositely charged surfactants (DEAB/SDS); in regard to the like charged SDS micellar systems, the sensitivity can be greatly enhanced by addition of a water soluble quencher which quenches the background fluorescence from the equilibrium population of free 12-DAN-ADA.

The growth of surfactant micelles can be sensitively detected by measuring the fluorescence anisotropy or the fluorescence maximum of a surfactant type fluorescence probe 12-DAN-ADA.Figure optionsDownload high-quality image (59 K)Download as PowerPoint slideResearch highlights
► A novel anionic surfactant type fluorescence probe with the fluorescent group attached to the end of the chain was designed.
► The fluorescent group can be tethered deep into the micellar cores.
► The growth of micelles can be detected by using this new type of fluorescence probe.
► The sensibility of the probe can be enhanced considerably if the background fluorescence is quenched by water soluble quenchers.