Electrostatic Interactions Influence Protein Adsorption (but Not Desorption) at the Silica-Aqueous Interface
Electrostatic Interactions Influence Protein Adsorption (but Not Desorption) at the Silica-Aqueous Interface
复制标题
DOI：
10.1021/acs.jpclett.5b00933
复制
发表时间：
2015-07-02
影响因子：
5.7
通讯作者：
Schwartz, Daniel K.
中科院分区：
文献类型：
--
作者：
McUmber, Aaron C.;Randolph, Theodore W.;Schwartz, Daniel K.
采用高通量单分子全内反射荧光显微镜研究了 pH 值和离子强度对牛血清白蛋白 (BSA) 在水-熔融石英界面吸附、解吸和界面扩散的影响。在高 pH 值和低离子强度下，带负电荷的 BSA 缓慢吸附到带负电荷的熔融二氧化硅表面。在低 pH 值和低离子强度下，BSA 带正电荷，或者在较高离子强度的溶液中，吸附速度大约快 1000 倍。有趣的是，BSA 的表面停留时间和界面扩散系数均不受 pH 值或离子强度的影响。这些发现表明，吸附动力学由与静电相互作用相关的能垒主导，但一旦吸附，蛋白质-表面相互作用则由短程非静电相互作用主导。这些结果凸显了单分子技术在稳态条件下分离基本过程（例如吸附和解吸）的能力，而使用整体平均方法无法测量这一过程。
High-throughput single-molecule total internal reflection fluorescence microscopy was used to investigate the effects of pH and ionic strength on bovine serum albumin (BSA) adsorption, desorption, and interfacial diffusion at the aqueous-fused silica interface. At high pH and low ionic strength, negatively charged BSA adsorbed slowly to the negatively charged fused silica surface. At low pH and low ionic strength, where BSA was positively charged, or in solutions at higher ionic strength, adsorption was approximately 1000 times faster. Interestingly, neither surface residence times nor the interfacial diffusion coefficients of BSA were influenced by pH or ionic strength. These findings suggested that adsorption kinetics were dominated by energy barriers associated with electrostatic interactions, but once adsorbed, protein-surface interactions were dominated by short-range nonelectrostatic interactions. These results highlight the ability of single-molecule techniques to isolate elementary processes (e.g., adsorption and desorption) under steady-state conditions, which would be impossible to measure using ensemble-averaging methods.