Ugolotti Aldo, Dolce Mirko, Di Valentin Cristiana
Dipartimento di Scienza dei Materiali, Università di Milano-Bicocca, via R. Cozzi 55, 20125 Milano, Italy.
BioNanoMedicine Center NANOMIB, Università di Milano-Bicocca, via Follereau 3, 20854 Vedano al Lambro, Italy.
Nanomaterials (Basel). 2024 Jan 25;14(3):261. doi: 10.3390/nano14030261.
Titanium dioxide nanotubes (TNT) have been extensively studied because of their unique properties, which make such systems ideal candidates for biomedical application, especially for the targeted release of drugs. However, knowledge about the properties of TiO nanotubes with typical dimensions of the order of the nanometer is limited, especially concerning the adsorption of molecules that can be potentially loaded in actual devices. In this work, we investigate, by means of simulations based on hybrid density functional theory, the adsorption of Vitamin C molecules on different nanotubes through a comparative analysis of the properties of different structures. We consider two different anatase TiO surfaces, the most stable (101) and the more reactive (001)A; we evaluate the role of the curvature, the thickness and of the diameter as well as of the rolling direction of the nanotube. Different orientations of the molecule with respect to the surface are studied in order to identify any trends in the adsorption mechanism. Our results show that there is no preferential functional group of the molecule interacting with the substrate, nor any definite spatial dependency, like a rolling orientation or the concavity of the nanotube. Instead, the adsorption is driven by geometrical factors only, i.e., the favorable matching of the position and the alignment of any functional groups with undercoordinated Ti atoms of the surface, through the interplay between chemical and hydrogen bonds. Differently from flat slabs, thicker nanotubes do not improve the stability of the adsorption, but rather develop weaker interactions, due to the enhanced curvature of the substrate layers.
二氧化钛纳米管（TNT）因其独特的性质而受到广泛研究，这些性质使此类体系成为生物医学应用的理想候选者，特别是在药物的靶向释放方面。然而，关于典型尺寸在纳米量级的TiO纳米管性质的知识有限，尤其是关于可能加载在实际装置中的分子的吸附情况。在这项工作中，我们通过基于混合密度泛函理论的模拟，通过对不同结构性质的比较分析，研究了维生素C分子在不同纳米管上的吸附。我们考虑了两种不同的锐钛矿TiO表面，最稳定的（101）面和反应性更强的（001）A面；我们评估了曲率、厚度、直径以及纳米管的滚动方向的作用。研究了分子相对于表面的不同取向，以确定吸附机制中的任何趋势。我们的结果表明，分子与底物相互作用没有优先的官能团，也没有任何确定的空间依赖性，如滚动取向或纳米管的凹面。相反，吸附仅由几何因素驱动，即通过化学键和氢键之间的相互作用，任何官能团的位置和排列与表面低配位Ti原子的良好匹配。与平板不同，较厚的纳米管不会提高吸附的稳定性，反而会由于底物层曲率的增加而产生较弱的相互作用。
