Selli Daniele, Valentin Cristiana Di
Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca , via Cozzi 55 20125 Milano, Italy.
J Phys Chem C Nanomater Interfaces. 2016 Dec 29;120(51):29190-29201. doi: 10.1021/acs.jpcc.6b09554. Epub 2016 Oct 25.
In biomedical applications, TiO nanoparticles are generally coated with polymers to prevent agglomeration, improve biocompatibility, and reduce cytotoxicity. Although the synthesis processes of such composite compounds are well established, there is still a substantial lack of information on the nature of the interaction between the titania surface and the organic macromolecules. In this work, the adsorption of polyethylene glycol (PEG) on the TiO (101) anatase surface is modeled by means of dispersion-corrected density functional theory (DFT-D2) calculations. The two extreme limits of an infinite PEG polymer [-(OCHCH) ], on one side, and of a short PEG dimer molecule [H(OCHCH)OH], on the other, are analyzed. Many different molecular configurations and modes of adsorption are compared at increasing surface coverage densities. At low and medium coverage, PEG prefers to lay down on the surface, while at full coverage, the adsorption is maximized when PEG molecules bind perpendicularly to the surface and interact with each other through lateral dispersions, following a mushroom to brush transition. Finally, we also consider the adsorption of competing water molecules at different coverage densities, assessing whether PEG would remain bonded to the surface or desorb in the presence of the aqueous solvent.
在生物医学应用中，二氧化钛纳米颗粒通常会被聚合物包覆，以防止团聚、提高生物相容性并降低细胞毒性。尽管此类复合化合物的合成工艺已相当成熟，但关于二氧化钛表面与有机大分子之间相互作用的本质，仍存在大量信息缺失。在这项工作中，通过色散校正密度泛函理论（DFT-D2）计算，对聚乙二醇（PEG）在TiO（101）锐钛矿表面的吸附进行了建模。一方面分析了无限长PEG聚合物[-（OCHCH）]的两个极端极限情况，另一方面分析了短PEG二聚体分子[H（OCHCH）OH]的情况。在不断增加的表面覆盖密度下，比较了许多不同的分子构型和吸附模式。在低覆盖度和中等覆盖度时，PEG倾向于平铺在表面，而在完全覆盖时，当PEG分子垂直于表面结合并通过横向色散相互作用时，吸附达到最大值，呈现从蘑菇状到刷状的转变。最后，我们还考虑了在不同覆盖密度下竞争性水分子的吸附情况，评估在水性溶剂存在的情况下PEG是否会保持与表面结合或解吸。
