去氧胆酸钠在水溶液中的簇集行为

Aggregation of Sodium Deoxycholate in Aqueous Solution

用外源荧光探针法和旋光度、电导率及pH滴定法研究了去氧胆酸钠(SDOC)在水溶液中的簇集行为.SDOC浓度低于5×10^(-3)～6×10^(-3)mol/L时在水溶液中以二元缔合物形式存在,具有较高的对称性和较弱的碱性并能提供一定的疏水性微环境;浓度高于该值后簇集成胶束,但簇集数(8～10)较小,同时伴随着对称性略微降低和碱性有所提高.

The aggregation behavior of a steroidal surfactant--sodium deoxycholate (SDOC) inaqueous solution was studied by extrinsic fluorescent probe [via twisted intramolecular charge transfer (TICT) fluorescence characteristics of p-N,N-dimethylamminobenzaldehyde, DMABA], optical rotation , conductivity, and pH measurement. TICT fluorescence band of DMABA shifts to blue and the fluorescence intensity ratio (Ia/Ib) of TICT band to LE band increases with the increase of SDOC concentration up to 6. 0× 10-3 mol/L, then the variation trends reversed. These results indicate that the critical micelle concentration of SDOC is 6. 0×10-3 mol/L and that the SDOC molecules don't exist in monomer but in dimer which provides a hydrophobic microenvironment less polar than that of SDOC micelle. Fittig the conductivity data of aqueous SDOC solution yields an average aggregation number of 8-10 for SDOC micelle which is substantially less than that of normal micelle. Optical rotation and pH measurements show that SDOC micelle has a relatively lower symmetry and stronger basicity than the dimer.