Jana Asis K, Tiwari Mrityunjay K, Vanka Kumar, Sengupta Neelanjana
Physical Chemistry Division, CSIR-National Chemical Laboratory, Pune 411008, India.
Phys Chem Chem Phys. 2016 Feb 17;18(8):5910-24. doi: 10.1039/c5cp04675k.
Emerging nanotechnology has rapidly broadened interfacial prospects of biological molecules with carbon nanomaterials (CNs). A prerequisite for effectively harnessing such hybrid materials is a multi-faceted understanding of their complex interfacial interactions as functions of the physico-chemical characteristics and the surface topography of the individual components. In this article, we address the origins of the curvature dependence of polypeptide adsorption on CN surfaces (CNSs), a phenomenon bearing an acute influence upon the behavior and activity of CN-protein conjugates. Our benchmark molecular dynamics (MD) simulations with the amphiphilic full-length amyloid beta (Aβ) peptide demonstrate that protein adsorption is strongest on the concave (inner) CN surface, weakest on the convex (outer) surface, and intermediary on the planar surface, in agreement with recent experimental reports. The curvature effects, however, are found to manifest non-uniformly between the amino acid subtypes. To understand the underlying interplay of the chemical nature of the amino acids and surface topography of the CNs, we performed high-level quantum chemical (QM) calculations with amino acid analogs (AAA) representing their five prominent classes, and convex, concave and planar CN fragments. Molecular electrostatic potential maps reveal pronounced curvature dependence in the mixing of electron densities, and a resulting variance in the stabilization of the non-covalently bound molecular complexes. Interestingly, our study revealed that the interaction trends of the high-level QM calculations were captured well by the empirical force field. The findings in this study have important bearing upon the design of carbon based bio-nanomaterials, and additionally, provide valuable insights into the accuracy of various computational techniques for probing non-bonded interfacial interactions.
新兴的纳米技术迅速拓宽了生物分子与碳纳米材料（CNs）的界面前景。有效利用此类混合材料的一个先决条件是从多个方面理解它们复杂的界面相互作用，这些相互作用是各组分物理化学特性和表面形貌的函数。在本文中，我们探讨了多肽在CN表面（CNSs）吸附的曲率依赖性的起源，这一现象对CN - 蛋白质缀合物的行为和活性有着深刻影响。我们用两亲性全长淀粉样β（Aβ）肽进行的基准分子动力学（MD）模拟表明，蛋白质吸附在凹面（内）CN表面最强，在凸面（外）表面最弱，在平面表面居中，这与最近的实验报告一致。然而，发现曲率效应在氨基酸亚型之间表现不一致。为了理解氨基酸化学性质与CNs表面形貌之间的潜在相互作用，我们用代表其五个主要类别的氨基酸类似物（AAA）以及凸面、凹面和平面CN片段进行了高水平量子化学（QM）计算。分子静电势图揭示了电子密度混合中明显的曲率依赖性，以及由此导致的非共价结合分子复合物稳定性的差异。有趣的是，我们的研究表明经验力场能很好地捕捉高水平QM计算的相互作用趋势。本研究的结果对碳基生物纳米材料的设计具有重要意义，此外，还为探索非键合界面相互作用的各种计算技术的准确性提供了有价值的见解。
