Rapid Fabrication, Microstructure, and in Vitro and in Vivo Investigations of a High-Performance Multilayer Coating with External, Flexible, and Silicon-Doped Hydroxyapatite Nanorods on Titanium

Abstract

A high-performance multilayer coating with external, flexible, and silicon-doped hydroxyapatite (Si-HA) nanorods was designed using bionics. Plasma electrolytic oxidation (PEO) and the microwave hydrothermal (MH) method were used to rapidly deposit this multilayer coating on a titanium (Ti) substrate, applied for 5 and 10 min, respectively. The bioactive multilayer coating was composed of four layers, and the outermost layer was an external growth layer that consisted of many Si-HA nanorods with a singlecrystal structure. The Si-HA nanorods exhibited good flexibility, likely because of their complete single-crystal structures, smooth surfaces, and suitable diameters and lengths. This multilayer coating with a high surface energy was superhydrophilic and exhibited good in vitro bioactivities, such as good apatite formation ability, good cell spreading, and high osteogenic gene expression levels. After implantation in the tibia of rabbits for 16 weeks, almost no soft tissues were formed at the MH treated PEO implant-bone interface. A direct bone contact interface was formed by a bridging effect of the flexible Si-HA nanorods, which further produced a high implant-bone interface bonding strength. The current results demonstrated that the bioactive multilayer layers with the flexible Si-HA nanorods displayed a very good osseointegration ability, showing promising applications in the biomedical field.

In situ titanium phosphate formation on a titanium implant as ultrahigh bonding with nano-hydroxyapatite coating for rapid osseointegration

“…We can observe that there is no fracture of the peri -implant bone 2 weeks after the operation, indicating that the implant can be used for replacement and load-bearing situations, such as dentistry and orthopedics. 53 The regenerated bone structure around the implant was reconstructed and analyzed by μ-CT 4 weeks after implantation. Assessing changes in complex bone formation around implants is more intuitive due to the natural radiopacity of Ti materials.…”

Rapid structural regulation, apatite-inducing mechanism and in vivo investigation of microwave-assisted hydrothermally treated titania coating

“…The details of the MAO treatment process have been reported in our previous studies. [40][41][42] For the MH treatment, the MAO specimens were treated in a reaction kettle containing 40 mL of different concentrations of NaOH solution, followed by microwave hydrothermal treatment at 200 C for 10 min (XH-800S, Beijing Xianghu Science and Technology Development Co., China). During the MH treatment process, the microwave frequency and power were set to 2450 MHz and 800 W, respectively.…”

“…The previous literature study reported that the ionic substituted HA nanorods such as Sr, Si and F ions had higher solubility. 42,43 In addition, the Sidoped HA crystals had higher solubility than the pure HA crystals because the substitution of PO 4 3À by SiO 4 3À ions could change the crystal structure of the HA phase. Therefore, the Si-HA crystals were easily degraded owing to the formation of the crystal defects aer the substitution.…”

“…Previous literature studies have reported that the HA nanomaterial enhances the osteoblast adhesion ability, thus further promoting the in vivo osseointegration ability. 42,43,45 Moreover, the Si-substituted HA crystals can accelerate the expression of the related osteoblast genes, thus, promoting the cell-material interaction ability and improving the in vivo interface status. 55,56 Based on the comprehensive factors, the MAOMH001 sample with Si-HA nanorods exhibited excellent osseointegration and in vivo interface status.…”

Microwave-assisted synthesis of composites based on titanium and hydroxyapatite for dental implantation

“…Many studies have confirmed that microwave heating could achieve better performance than conventional heating in materials synthesis and processing. [12][13][14][15] Microwave energy is characterized by the volumetric thermal effect due to its large wavelength, which allows the energy to be absorbed in a large material volume (Fig. 1).…”