Materials Research Centre, Indian Institute of Science, Bangalore 560012, India.
Center for Condensed Matter Theory, Department of Physics, Indian Institute of Science, Bangalore 560012, India.
J Phys Chem B. 2021 Jan 14;125(1):3-16. doi: 10.1021/acs.jpcb.0c08255. Epub 2021 Jan 4.
In experimental research-driven biomaterials science, the influence of different material properties (elastic stiffness, surface energy, etc.) and, to a relatively lesser extent, biophysical stimulation (electric/magnetic) on cell-material interactions has been extensively investigated. Despite the central importance of protein adsorption on cell-material interactions, the quantitative analysis to probe into the role of physicochemical factors in protein adsorption remains largely unexplored in biomaterials science. In recent studies, the critical role of electric field stimulation toward the modulation of cell functionality in implantable biomaterials has been experimentally demonstrated. Given this background, we investigated the influence of external electric field stimulation (upto 1.00 V/nm) on fibronectin (FN) adsorption on a hydroxyapatite (HA) (001) surface at 300 K using the all-atom molecular dynamics (MD) simulation method. FN adsorption was found to be governed by attractive electrostatic interactions, which changed with the electric field strength. Nonmonotonous changes in the structural integrity of FN were recorded with the change in the field strength and direction. This can be attributed to the spatial rearrangement of the positions of local charges and the global structural changes of proteins. The dipole moment vectors of FN, water, and HA quantitatively exhibited a similar pattern of orienting themselves parallel to the field direction, with field strength-dependent increase in their magnitudes. No significant change has been recorded for the radial distribution function of water surrounding FN. Field-dependent variation in the salt bridge nets and the number of hydrogen bonds between FN and HA were also examined. One of the important results in the context of cell-material interaction is that the RGD (Arg-Gly-Asp) sequence of FN was exposed to the solvent side when the field was applied along an outward direction perpendicular to the HA (001) surface. In summary, the present study provides molecular insights into the influence of electric field stimulation on phenomenological interactions involved in FN adsorption on the HA surface.
在以实验为导向的生物材料科学研究中，广泛研究了不同材料特性（弹性刚度、表面能等）以及在相对较小程度上的生物物理刺激（电/磁）对细胞-材料相互作用的影响。尽管蛋白质吸附对细胞-材料相互作用至关重要，但在生物材料科学中，对于探究物理化学因素在蛋白质吸附中的作用的定量分析仍在很大程度上尚未得到探索。在最近的研究中，已经实验证明了电场刺激在调节可植入生物材料中的细胞功能方面的关键作用。鉴于此背景，我们使用全原子分子动力学（MD）模拟方法研究了外加电场刺激（高达 1.00 V/nm）对 300 K 时纤维连接蛋白（FN）在羟基磷灰石（HA）（001）表面上吸附的影响。FN 的吸附由吸引力静电相互作用控制，该相互作用随电场强度而变化。随着场强的变化，记录到 FN 的结构完整性发生了非单调变化。这可以归因于局部电荷位置的空间重排和蛋白质的整体结构变化。FN、水和 HA 的偶极矩向量在定量上表现出相似的模式，即它们自身平行于场方向取向，并且其大小随场强的增加而增加。FN 周围水的径向分布函数没有记录到明显变化。还检查了 FN 与 HA 之间盐桥网络和氢键数量的场依赖性变化。在细胞-材料相互作用方面的一个重要结果是，当电场沿垂直于 HA（001）表面的外向方向施加时，FN 的 RGD（精氨酸-甘氨酸-天冬氨酸）序列暴露于溶剂侧。总之，本研究提供了关于电场刺激对 FN 在 HA 表面上吸附的现象学相互作用的影响的分子见解。
