The Interphase Electric Properties of SDS/n‐C₅H₁₁OH/L‐Phenylalanine/H₂O System

Abstract

The interphase electric properties of the SDS/n-C 5 H 11 OH/L-phenylalanine (L-phe)/H 2 O system have been investigated by the method of AC impedance. The results show that at the constant weight ratio of n-C 5 H 11 OH/H 2 O 5 50/50 and the total L-phe concentration, with an increase of the total concentration of sodium dodecyl sulfate (SDS) in the system, the structure of the upper phase always takes W/O (water/oil) form, whereas that of the lower phase changes from O/W (oil/water) to BI (bi-continuous) when the total concentration of SDS reaches 3.0%. The microstructure transition of microemulsions at the SDS concentration of 3.0% makes the increase of the interphase capacitance and interphase charge-transfer current apparently slow down with further increase of SDS concentration. In addition, L-phe can transfer from the lower phase to the upper phase with increase of the total SDS concentration. At a constant concentration of SDS, with an increase of the total L-phe concentration, the concentrations of L-phe in both the upper and lower phases increase the interphase capacitance and the interphase charge-transfer current of the system increase first rapidly and then slowly, but the interphase resistivity of the system decreases first rapidly and then slowly.

Distribution and Transfer of Gatifloxacin Between Two Microemulsion Phases with Different Structures in SDS/n‐C5H11OH/H2O System

“…With the constant weight ratio of n-C 5 H 11 OH/H 2 O at 50/50 and the rise in the total SDS content in the system, the increase of SDS content in the upper phase was different from that in the lower phase. 19 And so the changes of structures in these two phases were different either. Corresponding to the slow increase of the SDS content in the upper phase, the upper phase was always W/O microemulsion.…”

“…Therefore in our studied system, we chose the liquid-liquid interface formed by the surfactant aggregation, namely water in oil (W/O) -oil in water (O/W) interface or W/O-bicontinuous (BI) interface, which can be taken as half a model of biological membrane. In the previous papers we have studied the effects of Lphenylalanine 19 and malachite green 20 on the interphase electric properties of the O/W-W/O interface and of the W/O-BI interface in the SDS/n-C 5 H 11 OH/H 2 O system by the methods of AC impedance and cyclic voltammetry. Electrochemical measurements of these liquid-liquid interfaces can provide information about osmosis and transfer of bioactive materials across them, and will be a new method for the study of microemulsion interphase properties.…”

Distribution and structural behavior of hemoglobin between the two phases in SDS/n-C5H11OH/H2O system

“…When the total SDS content is less than 3.0% (wt), the upper phase is W/O microemulsion, and the lower phase is O/W microemulsion. When the total SDS content is greater than 3.0%, the upper phase is still W/O microemulsion, while the lower phase turns into bicontinuous microemulsion that presents a network structure composed of O/W and W/O structures [11,12].…”

“…The liquid-liquid interface formed by the surfactant aggregation, such as the W/O-O/W interface or W/O-BI interface, can be used to mimic biological membrane since it provides a hydrophobic-hydrophilic medium. We have studied the distribution and transfer of l-phenylalanine [11] and l-tryptophan [12] through the water-in-oil (W/O)-oil-in-water (O/W) interface and W/O-BI (bicontinuous) interface in SDS/n-C 5 H 11 OH/H 2 O system by means of UV-vis spectroscopy and AC impedance. The results indicate that the transfer and distribution of biologically active substance between the inside and outside of the membrane can be adjusted by constitutes of the upper and lower phases, and provide theoretical basis for the behavior of the biologically active * Corresponding author.…”

Transfer and distribution of L-tryptophan between W/O and O/W, and between W/O and bicontinuous microemulsions through the study of interphase electric properties

“…Studies of the electric properties of a liquid-liquid interface, as well as the mass transfer behavior via the interface, are of great significance to the thermodynamic and dynamic foundations for the simulation of ion transfer through biological membranes [3][4][5][6][7][8][9][10][11][12][13][14][15][16]. We have studied the electric properties of the O/W-W/O interface and the W/O-BI interface in the SDS/n-C 5 H 11 OH/H 2 O system [17] and the influence of malachite green [18] and L-phenylalanine [19] on the interfacial electric properties of the SDS/n-C 5 H 11 OH/H 2 O system by means of cyclic voltammetry and AC impedance. These provide some useful information about mass transfer between microemulsion phases with different structures.…”