Robinson R L, Strickholm A
Biochim Biophys Acta. 1978 May 4;509(1):9-20. doi: 10.1016/0005-2736(78)90003-2.
Black lipid membranes made from oxidized cholesterol were examined for their specific resistance, capacitance, and physical stability, as a function of cholesterol oxidation time and of age. Membranes formed from cholesterol oxidized in n-octane were not physically stable even after 7 h of oxidation unless they were aged for at least a month. Membranes formed from cholesterol oxidized in decane and tetradecane (1 : 1) were stable immediately after 2--6 h of oxidation. Oxidation times outside this range produced unstable membranes. After 1 month storage, membranes from cholesterol solutions oxidized in decane and tetradecane from 0.75--3 h were stable. After 11 months, only the 0.75 oxidation time produced stable membranes. Storage in nitrogen retarded the aging process. After initial forming of the membrane, total membrane area and capacity increased and then stabilized, although specific capacity and resistance did not change, indicating inherent stability in the bilayer's intrinsic electrical properties. Bilayers formed soon after cholesterol oxidation had membrane capacity which ranged from 0.42 to 0.55 muF/cm2. Specific membrane resistance ranged initially from 2 . 10(6) to 37 . 10(6) omega/cm2 in 0.2 M NaCl with lower resistances in the more oxidized membranes. With aging, membrane capacity decreased gradually over 11 months to values approaching 0.1 muF/cm2 indicating membrane thickening. Membrane resistance ordinarily decreases with storage time. The rate of these changes with age is dependent on the extent of initial cholesterol oxidation and subsequent oxidation, with long term stability best in the least oxidized membranes.
对由氧化胆固醇制成的黑色脂质膜的比电阻、电容和物理稳定性进行了研究，作为胆固醇氧化时间和老化时间的函数。由在正辛烷中氧化的胆固醇形成的膜即使在氧化7小时后也没有物理稳定性，除非它们老化至少一个月。由在癸烷和十四烷（1:1）中氧化的胆固醇形成的膜在氧化2至6小时后立即稳定。超出此范围的氧化时间会产生不稳定的膜。储存1个月后，由在癸烷和十四烷中氧化0.75至3小时的胆固醇溶液形成的膜是稳定的。储存11个月后，只有0.75的氧化时间产生稳定的膜。在氮气中储存会延缓老化过程。在膜最初形成后，总膜面积和电容增加然后稳定，尽管比电容和电阻没有变化，这表明双层膜的固有电性能具有内在稳定性。胆固醇氧化后不久形成的双层膜的膜电容范围为0.42至0.55 μF/cm²。在0.2 M NaCl中，特定膜电阻最初范围为2×10⁶至37×10⁶ Ω/cm²，氧化程度越高的膜电阻越低。随着老化，膜电容在11个月内逐渐降低至接近0.1 μF/cm²的值，表明膜增厚。膜电阻通常随储存时间降低。这些随年龄变化的速率取决于初始胆固醇氧化和后续氧化的程度，氧化程度最低的膜长期稳定性最佳。
