Abstract
The estimation of the critical micelle concentration (cmc) of various lysolecithins with 2-p-toluidinylnaphthalene-6-sulfonate (TNS) and 1-anilinonaphthalene-8-sulfonate (ANS) as fluorescent probes was investigated. The fluorescence yield of TNS in palmitoyl lysolecithin micellar phase was found to be somewhat larger than that of ANS. Further, the fluorescence yield of TNS in the aqueous phase is known to be much smaller than that of ANS. Thus, TNS should be useful for estimating very small cmc values of surfactants such as lysolecithins. The cmc values of lysolecithins estimated by using TNS were 0.5mM for lauroyl lysolecithin, 63μM for myristoyl lysolecithin, 8.3μM for palmitoyl lysolecithin and 6.6μM for oleoyl lysolecithin, in 20mM Tris-HCl buffer solution (pH7.0) at 25°C. It was also found that stearoyl lysolecithin does not form micelles at room temperature, and the Krafft point is about 60°C.
