Animal Origin Bioactive Hydroxyapatite Thin Films Synthesized by RF-Magnetron Sputtering on 3D Printed Cranial Implants

Abstract

Ti6Al4V cranial prostheses in the form of patterned meshes were 3D printed by selective laser melting in an argon environment; using a CO2 laser source and micron-sized Ti6Al4V powder as the starting material. The size and shape of prostheses were chosen based on actual computer tomography images of patient skull fractures supplied in the framework of a collaboration with a neurosurgery clinic. After optimizations of scanning speed and laser parameters, the printed material was defect-free (as shown by metallographic analyses) and chemically homogeneous, without elemental segregation or depletion. The prostheses were coated by radio-frequency magnetron sputtering (RF-MS) with a bioactive thin layer of hydroxyapatite using a bioceramic powder derived from biogenic resources (Bio-HA). Initially amorphous, the films were converted to fully-crystalline form by applying a post-deposition thermal-treatment at 500 °C/1 h in air. The X-ray diffraction structural investigations indicated the phase purity of the deposited films composed solely of a hexagonal hydroxyapatite-like compound. On the other hand, the Fourier transform infrared spectroscopic investigations revealed that the biological carbonatation of the bone mineral phase was well-replicated in the case of crystallized Bio-HA RF-MS implant coatings. The in vitro acellular assays, performed in both the fully inorganic Kokubo’s simulated body fluid and the biomimetic organic–inorganic McCoy’s 5A cell culture medium up to 21 days, emphasized both the good resistance to degradation and the biomineralization capacity of the films. Further in vitro tests conducted in SaOs-2 osteoblast-like cells showed a positive proliferation rate on the Bio-HA RF-MS coating along with a good adhesion developed on the biomaterial surface by elongated membrane protrusions.

Metal Additive Manufacturing—State of the Art 2020

“…3D cranial meshes of Ti6Al4V were successfully manufactured using SLM and coated using radio-frequency magnetron sputtering with a~600-nanometer layer of hydroxyapatite that was derived from biogenic sustainable resources (i.e., calcined cortical bovine bones). The Bio-HA sputtered films elicited promising biological performances [9].…”

Metal Matrix Composites Synthesized by Laser-Melting Deposition: A Review

“…It showed that they could be used for load-bearing implants such as hip, knee and shoulder joints [ 151 , 152 ]. Moreover, orthopedic bone prototypes and meshed cranial prostheses implants were successfully developed for biomedical applications [ 57 , 153 , 154 ].…”

Fish Bone Derived Bi-Phasic Calcium Phosphate Coatings Fabricated by Pulsed Laser Deposition for Biomedical Applications

“…The PLD coated samples were immersed in 1 mL of the same cell culture medium (i.e., DMEM supplemented with 10% fetal bovine serum), used in the case of the cytocompatibility assay, detailed here-under. Recent developments have indicated that a more truthful evaluation of the degradation speed/biomineralization capacity of a material can be achieved by testing under cell culture media, and not in the simplistic simulated body fluids such as Tris-HCl or Kokubo SBF, since the cell culture media reproduces with higher accuracy the composition of the intercellular medium [59,64,79]. The solubility/bioactivity in vitro tests were carried out in a dedicated biological incubator under homeostatic conditions (i.e., humidified atmosphere, temperature of 37 • C, and partial pressure of CO 2 of 5 kPa) for different time periods of 1, 3, and 7 days, respectively.…”