Density Functional Theory Study of Interface Interactions in Hydroxyapatite/Rutile Composites for Biomedical Applications

Abstract

To gain insight into the nature of the adhesion mechanism between hydroxyapatite (HA) and rutile (rTiO 2 ), the mutual affinity between their surfaces was systematically studied using density functional theory (DFT). We calculated both bulk and surface properties of HA and rTiO 2 , and explored the interfacial bonding mechanism of amorphous HA (aHA) surface onto amorphous as well as stoichiometric and nonstoichiometric crystalline rTiO 2 . Formation energies of bridging and subbridging oxygen vacancies considered in the rTiO 2 (110) surface were evaluated and compared with other theoretical and experimental results. The interfacial interaction was evaluated through the work of adhesion. For the aHA/rTiO 2 (110) interfaces, the work of adhesion is found to depend strongly on the chemical environment of the rTiO 2 (110) surface. Electronic analysis indicates that the charge transfer is very small in the case of interface formation between aHA and crystalline rTiO 2 (110). In contrast, significant charge transfer occurs between aHA and amorphous rTiO 2 (aTiO 2 ) slabs during the formation of the interface. Charge density difference (CDD) analysis indicates that the dominant interactions in the interface have significant covalent character, and in particular the Ti−O and Ca−O bonds. Thus, the obtained results reveal that the aHA/aTiO 2 interface shows a more preferable interaction and is thermodynamically more stable than other interfaces. These results are particularly important for improving the long-term stability of HA-based implants.

Effect of van der Waals interactions on the adhesion strength at the interface of the hydroxyapatite–titanium biocomposite: a first-principles study

“…For creating the Si substituted interfaces we used the a-HAP/a-TiO 2 model with two possible stacking positions, which resulted in the best interatomic interaction. 37 In this study, the aim is to improve our understanding of the interaction between the a-HAP coating and the a-TiO 2 substrate. For this purpose, we focus on the comparison of the results obtained for two best stacking positions of each considered interfaces, and calculated with normal GGA and dispersioncorrected DFT-D3 functionals.…”

“…The DFT-D3 method is used to account for dispersion corrections. A detailed description of the construction of the considered interfaces and the amorphization procedure can be found in our previous works 28,37 and ESI. † The atomic structures are visualized by the VESTA 3 program.…”

Synthesis and structure determination of calcium silicate‐cellulose nanograss biocomposite

“…In recent days, advance DFT and PDF techniques are used to dig out short‐range structural information of the materials, which process poor crystalline characteristic such as amorphous silica, porous carbon materials as well as calcium silicate hydrate . In addition, the interactions of collagen peptides with hydroxyapatite surfaces, Hyp‐Pro‐Gly peptide with hydroxyapatite surfaces, and hydroxyapatite with rutile surfaces can be determined by these techniques. These are also used to understand the short‐range interaction in amorphous silica and quartz …”

“…Recent reports claim that in order to get the desired property and high performance, a comprehensive and systematic study involving both experiment and theory are required to provide an in‐depth understanding of interfacial behavior in composites . Thus, the determination of proper structure and interactions between individual constituents often play very important roles in controlling the properties of nanocomposites …”

“…23,[28][29][30] Thus, the determination of proper structure and interactions between individual constituents often play very important roles in controlling the properties of nanocomposites. [23][24][25][26][27]29,30 Hence, it seems plausible to argue that, in order to be able to appropriately control the development of calcium silicate-cellulose nanograss-like nanocomposites, experimental studies are required to understand (a) the growth process of cellulose and (b) the interaction between the organic cellulosic matrix and the calcium silicate crystal. This knowledge in turn helps us to understand how the atomic level binding of fibril like polymeric cellulose structures to the inorganic calcium silicate surfaces occurs.…”