Phosphate bioglass thin-films: Cross-area uniformity, structure and biological performance tailored by the simple modification of magnetron sputtering gas pressure

authors	Tite, T; Popa, AC; Chirica, IM; Stuart, BW; Galca, AC; Balescu, LM; Popescu-Pelin, G; Grant, DM; Ferreira, JMF; Stan, GE
nationality	International
journal	APPLIED SURFACE SCIENCE
author keywords	Implant coating; Phosphate bio-glass; Magnetron sputtering; Material engineering; Structure; Biological performance
keywords	BIOACTIVE GLASS; OPTICAL BASICITY; ELECTRONIC POLARIZABILITY; MECHANICAL-PROPERTIES; RAMAN; SPECTROSCOPY; TEMPERATURE; INFECTIONS; COATINGS; SPECTRA
abstract	Currently, there is a considerable time-lag in the industrialisation of innovative technological solutions for the functionalization of osseous implants, with ever-demanding healthcare requirements (e.g., controlled release of therapeutic ions, match of biomaterial degradation - bone growth rates, antimicrobial efficiency). As third-generation biomaterials, phosphate bio-glasses (PBGs) have demonstrated an ability to stimulate specific biological responses from tissue to molecular level, by successfully coupling bioactive and resorbable material properties. Here, radio-frequency magnetron sputtered (RF-MS) PBGs were explored as sacrificial resorbable layers for prospective biomedical implant designs. A PBG powder with a 50-P2O5, 35-CaO, 10-Na2O and 5-Fe2O3 composition (mol%) was used as source (target) material. The influence of the argon working pressure (0.2-1 Pa) - one of the most prominent RF-MS variables - on the morphology, structure, uniformity, composition, degradation rate and cytocompatibility of PBG films was investigated. The engineered modification of physical-chemical and biological features of the PBG sputtered films was multi-parametrically surveyed by AFM, EDXS, spectroscopic ellipsometry, GIXRD, FTIR spectroscopy measurements and in vitro assays. Results suggested that the film thickness, composition, density and structure were preserved over a uniformity region having a diameter of similar to 30 mm, irrespective of sputtering pressure. The network connectivity and the surface porosity of the films were found to have antagonistic roles with respect to the in vitro degradation performance. The possibility of fine tuning the composition, structure and thereby biological interaction of the PBG films by conveniently modifying the sputtering pressure was shown (i.e., permitting their complete controlled degradation, without cytotoxic effects). This work is the first to show in vitro cytocompatibility outcomes of sputtered PBG films and their cross-area uniformity, and thus, it could prove to be an important technological step in their future biomedical application and suggest implications for future industrial scale-up.
publisher	ELSEVIER
issn	0169-4332
isbn	1873-5584
year published	2021
volume	541
digital object identifier (doi)	10.1016/j.apsusc.2020.148640
web of science category	19
subject category	Chemistry, Physical; Materials Science, Coatings & Films; Physics, Applied; Physics, Condensed Matter
unique article identifier	WOS:000608507800004