Key Laboratory of Pollution Processes and Environmental Criteria (Ministry of Education), Tianjin Key Laboratory of Environmental Remediation and Pollution Control, College of Environmental Science and Engineering , Nankai University , Tianjin 300350 , P. R. China.
Environ Sci Technol. 2018 Jul 3;52(13):7212-7219. doi: 10.1021/acs.est.7b06218. Epub 2018 Jun 22.
The impacts of a model globular protein (bovine serum albumin, BSA) on aggregation kinetics of graphene oxide (GO) in aquatic environment were investigated through time-resolved dynamic light scattering at pH 5.5. Aggregation kinetics of GO without BSA as a function of electrolyte concentrations (NaCl, MgCl, and CaCl) followed the traditional Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, and the critical coagulation concentration (CCC) was 190, 5.41, and 1.61 mM, respectively. As BSA was present, it affected the GO stability in a concentration dependent manner. At fixed electrolyte concentrations below the CCC values, for example 120 mM NaCl, the attachment efficiency of GO increased from 0.08 to 1, then decreased gradually and finally reached up to zero as BSA concentration increased from 0 to 66.5 mg C/L. The low-concentration BSA depressed GO stability mainly due to electrostatic binding between the positively charged lysine groups of BSA and negatively charged groups of GO, as well as double layer compression effect. With the increase of BSA concentration, more and more BSA molecules were adsorbed on GO, leading to strong steric repulsion which finally predominated and stabilized the GO. These results provided significant information about the concentration dependent effects of natural organic matters on GO stability under environmentally relevant conditions.
通过在 pH 5.5 下使用时间分辨动态光散射研究了模型球状蛋白（牛血清白蛋白，BSA）对水环境污染中氧化石墨烯（GO）聚集动力学的影响。在没有 BSA 的情况下，GO 的聚集动力学作为电解质浓度（NaCl、MgCl 和 CaCl）的函数遵循传统的德加古恩-兰德维维尔-奥弗贝克（DLVO）理论，临界聚沉浓度（CCC）分别为 190、5.41 和 1.61mM。由于存在 BSA，它以浓度依赖的方式影响 GO 的稳定性。在低于 CCC 值的固定电解质浓度下，例如 120mM NaCl，GO 的附着效率从 0.08 增加到 1，然后逐渐降低，最后随着 BSA 浓度从 0 增加到 66.5mg C/L 增加到零。低浓度 BSA 降低了 GO 的稳定性，主要是由于 BSA 中带正电荷的赖氨酸基团与 GO 中带负电荷的基团之间的静电结合以及双电层压缩效应。随着 BSA 浓度的增加，越来越多的 BSA 分子被吸附在 GO 上，导致强烈的空间排斥，最终占主导地位并稳定了 GO。这些结果提供了有关在环境相关条件下天然有机物对 GO 稳定性的浓度依赖性影响的重要信息。
