Department of Chemical and Materials Engineering, University of Alberta , Edmonton, Alberta, T6G 2V4, Canada.
Biomacromolecules. 2013 Oct 14;14(10):3498-508. doi: 10.1021/bm400837t. Epub 2013 Oct 3.
Nonspecific adsorption of proteins on biomaterial surfaces challenges the widespread application of engineered materials, and understanding the impact of secondary structure of proteins and peptides on their adsorption process is of both fundamental and practical importance in bioengineering. In this work, poly-L-lysine (PLL)-based α-helices and β-sheets were chosen as a model system to investigate the effect of secondary structure on peptide interactions with substrates of various surface chemistries. Circular dichroism (CD) was used to confirm the presence of both α-helix and β-sheet structured PLL in aqueous solutions and upon adsorption to quartz, where these secondary structures seemed to be preserved. Atomic force microscopy (AFM) imaging showed different surface patterns for adsorbed α-helix and β-sheet PLL. Interactions between PLL of different secondary structures and various substrates (i.e., PLL, Au, mica, and poly(ethylene glycol) (PEG)) were directly measured using a surface forces apparatus (SFA). It was found that β-sheet PLL films showed higher adsorbed layer thicknesses in general. Adhesion energies of β-sheet versus Au and β-sheet versus β-sheet were considerably higher than that of α-helix versus Au and α-helix versus α-helix systems, respectively. Au and β-sheet PLL interactions seemed to be more dependent on the salt concentration than that of α-helix, while the presence of a grafted PEG layer greatly diminished any attraction with either PLL structure. The molecular interaction mechanism of peptide in different secondary structures is discussed in terms of Derjaguin-Landau-Verwey-Overbeek (DLVO) theory, Alexander-de Gennes (AdG) steric model and hydrogen bonding, which provides important insight into the fundamental understanding of the interaction mechanism between proteins and biomaterials.
蛋白质在生物材料表面的非特异性吸附给工程材料的广泛应用带来了挑战，而了解蛋白质和肽的二级结构对其吸附过程的影响在生物工程中具有基础和实际的重要性。在这项工作中，聚-L-赖氨酸 (PLL) 基的α-螺旋和β-折叠被选为模型体系，以研究二级结构对肽与各种表面化学物质底物相互作用的影响。圆二色性 (CD) 用于确认水溶液中和吸附到石英上的 PLL 中均存在α-螺旋和β-折叠结构，这些二级结构似乎得以保留。原子力显微镜 (AFM) 成像显示了吸附的α-螺旋和β-折叠 PLL 的不同表面图案。使用表面力仪 (SFA) 直接测量了不同二级结构的 PLL 与各种底物（即 PLL、Au、云母和聚乙二醇 (PEG)）之间的相互作用。结果发现，β-折叠 PLL 膜通常显示出更高的吸附层厚度。β-折叠相对于 Au 和β-折叠相对于β-折叠的粘附能明显高于α-螺旋相对于 Au 和α-螺旋相对于α-螺旋的系统。Au 和β-折叠 PLL 之间的相互作用似乎比α-螺旋更依赖于盐浓度，而接枝 PEG 层的存在则大大降低了与任何一种 PLL 结构的吸引力。根据德加古因-朗道-弗韦尔贝克 (DLVO) 理论、亚历山大-德热纳 (AdG) 位阻模型和氢键，讨论了不同二级结构中肽的分子相互作用机制，为深入了解蛋白质与生物材料之间的相互作用机制提供了重要的见解。
