Laboratory of Physical Chemistry, Department of Environmental and Natural Resources Management, University of Ioannina, Seferi 2, 30100 Agrinio, Greece.
J Colloid Interface Sci. 2011 Jun 15;358(2):575-81. doi: 10.1016/j.jcis.2011.03.060. Epub 2011 Mar 23.
The thermodynamics of adsorption of gallic acid (GA, 3,4,5-trihydroxylbenzoic acid) on the hanging mercury drop electrode (HMDE) surface was studied by temperature-dependent stripping voltammetry (TD-SV), at physiological pH 7.4. The thermodynamic parameters, e.g., Gibbs free energy, ΔG(ADS), enthalpy, ΔΗ(ADS) and entropy, ΔS(ADS), of adsorption have been determined at physiological temperatures 2-40 °C. Chemisorption of the radical species ≡[GA(OH)(2)(O(-))]* is the energetically important reaction. The thermodynamic data show a complex mechanism of adsorption of GA on the electrode surface, which is strongly dependent on temperature. At low-temperatures T<12 °C, adsorption is controlled by enthalpy, while at T>22 °C, adsorption is entropy driven. In the temperature range 12 °C and 22 °C, a combined enthalpy-entropy stabilization occurs. A mechanism is proposed which analyses the implication of thermodynamics to the interfacial adsorption of polyphenols with cell membranes under physiological conditions.
在生理 pH 值 7.4 下，通过温度依赖的溶出伏安法（TD-SV）研究了没食子酸（GA，3,4,5-三羟基苯甲酸）在悬汞电极（HMDE）表面的吸附热力学。在生理温度 2-40°C 下，确定了吸附的热力学参数，如吉布斯自由能ΔG(ADS)、焓ΔΗ(ADS)和熵ΔS(ADS)。自由基物种≡[GA(OH)(2)(O(-))]*的化学吸附是能量上重要的反应。热力学数据表明，GA 在电极表面的吸附存在复杂的机制，且强烈依赖于温度。在低温 T<12°C 下，吸附受焓控制，而在 T>22°C 时，吸附由熵驱动。在 12°C 和 22°C 的温度范围内，发生了焓熵联合稳定作用。提出了一种机制，该机制分析了热力学对多酚与细胞膜在生理条件下界面吸附的影响。
