Polarization and biomineralization of hydroxyapatite-barium titanate composites

Abstract

In the search of new materials for bone regeneration, the materials with piezoelectric properties look very promising. It has been reported that piezoelectric materials induce bone growth and enhance implant integration. Additionally, it has been found that bioactivity increases in negatively charge surfaces such as polarized BaTiO3 (BT) and polarized hydroxyapatite (HAp). Additionally, it is known that BaSO4 (BS) increases biocompatibility. Therefore, in this work, composites materials of 80BT/20BS (BTS) in different proportions with HAp (HAp/BTS: 10/90, 30/70, 50/50, 70/30 y 90/10) were prepared by a mixture of nanometric powders and then they were sintered at 1000 °C for a period of 5 h. The materials were polarized at 130, 300 and 400 °C applying a DC electric field of 1 kV/mm, during 1 h. The electric field was maintained until the material was cooled down to room temperature. The electric and piezoelectric response were measured immediately after cooling, after 1 h and after 24 h. The dielectric measurements of materials were performed at different frequencies (0.1 to 100 kHz). The polarized and unpolarized materials were immersed in simulated body fluid (1.5 SBF) for 7 and 19 days. The deposition and growth of hydroxyapatite using the biomimetic method was followed by FTIR and SEM. The polarization effect on the crystalline growth of hydroxyapatite formed from the SBF solution has been demonstrated. The process of biomineralization of HAp on HAp/BTS composites increased considerably with the addition of barium titanate, this effect greatly improved in polarized materials. The typical coral-like morphology characteristic of HAp formation from SBF deposition was observed after 7 days of SBF immersion for polarized composites. Excellent dielectric properties were determined by adding 30% Of BaTiO3, obtaining for these composites dielectric constant values of the order of 20 to 10 kHz, values similar to that of human bones. Therefore, these materials look very promising for bone regeneration.

The Effect of Doping on the Electrical and Dielectric Properties of Hydroxyapatite for Medical Applications: From Powders to Thin Films

“…Thus, it was shown that the ε1 values decreased when increasing the applied frequency. Notably, at each frequency, the ε1 values significantly decreased with the increase in the HA content: at 100 Hz, the ε1 values corresponding to 10% HA-90% BTS composite samples decreased by ~40% with a 10% The ε 1 values for HA-BTS sintered composites were also measured by Uribe et al [220] in the frequency range of 100 Hz to 100 kHz. Thus, it was shown that the ε 1 values decreased when increasing the applied frequency.…”

“…The ε1 values for HA-BTS sintered composites were also measured by Uribe et al [220] in the frequency range of 100 Hz to 100 kHz. Thus, it was shown that the ε1 values decreased when increasing the applied frequency.…”

Physicochemical, mechanical, dielectric, and biological properties of sintered hydroxyapatite/barium titanate nanocomposites for bone regeneration

“…A lack of calcium ions in nonstoichiometric HA can also cause this band to arise due to the stretching vibration caused by free OH groups of water molecules trapped in lattice vacancies of OH ions [37]. Overall, the non-sintered HA shows a band of OH − (3575 cm −1 ) stretching vibration, which gradually decreased in intensity with an increase in the sintering temperature and completely disappeared in the 5HA/95BT sintered nanocomposite with the lowest HA content [38].…”

“…Nanostructured HA-coated titanium and stainless-steel wires also showed induced expression of bone formation and provided osteointegration [76]. The biomineralization process of HA in HA/BT nanocomposites is significantly enhanced by the addition of BT and enhanced in polarized materials [38]. The in vitro experimentation of 10%HA/90%BT ceramics with increased BT content in dynamic loading device stimulated growth of osteoblasts and allows boneinducing activity without cytotoxicity [41].…”