Oliva Fabiana Y, Avalle Lucía B, Cámara Osvaldo R, De Pauli Carlos P
INFIQC-Departamento de Fisicoquímica, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina.
J Colloid Interface Sci. 2003 May 15;261(2):299-311. doi: 10.1016/S0021-9797(03)00029-8.
The adsorption of human serum albumin (HSA) onto colloidal TiO2 (P25 Degussa) particles was studied in NaCl electrolyte at different solution pH and ionic strength. The HSA-TiO2 interactions were studied using adsorption isotherms and the electrokinetic properties of HSA-covered TiO2 particles were monitored by electrophoretic mobility measurements. The adsorption behavior shows a remarkable dependence of the maximum coverage degree on pH and was almost independent of the ionic strength. Other characteristic features such as maximum adsorption values at the protein isoelectric point (IEP approximately 4.7) and low-affinity isotherms that showed surface saturation even under unfavorable electrostatic conditions (at pH values far away from the HSA IEP and TiO2 PZC) were observed. Structural and electrostatic effects can explain the diminution of HSA adsorption under these conditions, assuming that protein molecules behave as soft particles. Adsorption reactions are discussed, taking into account acid-base functional groups of the protein and the surface oxide in different pH ranges, considering various types of interactions.
在不同溶液pH值和离子强度的NaCl电解质中，研究了人血清白蛋白（HSA）在胶体TiO₂（德固赛P25）颗粒上的吸附情况。利用吸附等温线研究了HSA与TiO₂之间的相互作用，并通过电泳迁移率测量监测了HSA包覆的TiO₂颗粒的电动性质。吸附行为表明最大覆盖度对pH值有显著依赖性，而几乎与离子强度无关。还观察到了其他特征，如在蛋白质等电点（IEP约为4.7）处的最大吸附值，以及即使在不利的静电条件下（pH值远离HSA的IEP和TiO₂的PZC）也显示出表面饱和的低亲和力等温线。假设蛋白质分子表现为软颗粒，结构和静电效应可以解释在这些条件下HSA吸附的减少。考虑到蛋白质和表面氧化物在不同pH范围内的酸碱官能团，以及各种类型的相互作用，对吸附反应进行了讨论。
