The Beneficial Mechanical and Biological Outcomes of Thin Copper-Gallium Doped Silica-Rich Bio-Active Glass Implant-Type Coatings

Abstract

Silica-based bioactive glasses (SBG) hold great promise as bio-functional coatings of metallic endo-osseous implants, due to their osteoproductive potential, and, in the case of designed formulations, suitable mechanical properties and antibacterial efficacy. In the framework of this study, the FastOs®BG alkali-free SBG system (mol%: SiO2—38.49, CaO—36.07, P2O5—5.61, MgO—19.24, CaF2—0.59), with CuO (2 mol%) and Ga2O3 (3 mol%) antimicrobial agents, partially substituting in the parent system CaO and MgO, respectively, was used as source material for the fabrication of intentionally silica-enriched implant-type thin coatings (~600 nm) onto titanium (Ti) substrates by radio-frequency magnetron sputtering. The physico-chemical and mechanical characteristics, as well as the in vitro preliminary cytocompatibility and antibacterial performance of an alkali-free silica-rich bio-active glass coating designs was further explored. The films were smooth (RRMS < 1 nm) and hydrophilic (water contact angle of ~65°). The SBG coatings deposited from alkali-free copper-gallium co-doped FastOs®BG-derived exhibited improved wear performance, with the coatings eliciting a bonding strength value of ~53 MPa, Lc3 critical load value of ~4.9 N, hardness of ~6.1 GPa and an elastic modulus of ~127 GPa. The Cu and Ga co-doped SBG layers had excellent cytocompatibility, while reducing after 24 h the Staphylococcus aureus bacterial development with 4 orders of magnitude with respect to the control situations (i.e., nutritive broth and Ti substrate). Thereby, such SBG constructs could pave the road towards high-performance bio-functional coatings with excellent mechanical properties and enhanced biological features (e.g., by coupling cytocompatibility with antimicrobial properties), which are in great demand nowadays.

Advancement of Gallium and Gallium-Based Compounds as Antimicrobial Agents

“…On the one hand, hydrogel, bioceramics, and other materials with good biocompatibility can be directly used as tissue engineering scaffolds for the repair of infectious defects. On the other hand, chemical processes, such as electrophoretic deposition, thermochemical treatment (Rodriguez-Contreras et al, 2020), solid-state method (Pajor et al, 2020), radio-frequency magnetron sputtering (Stan et al, 2020), and gel/sol can form antibacterial coatings (Pajor et al, 2020;Rodriguez-Contreras et al, 2020;Stan et al, 2020;Almohandes et al, 2021;Centurion et al, 2021) containing gallium on the surface of implants to prevent and treat iatrogenic infections. The controlled release of gallium by the above materials mainly benefits from their biodegradability, porous network structure, and adjustable porosity.…”

Fiber-Templated 3D Calcium-Phosphate Scaffolds for Biomedical Applications: The Role of the Thermal Treatment Ambient on Physico-Chemical Properties

“…A higher value of the surface free energy is an indicator of an increased hydrophilicity. In this regard, the 50–80° range was suggested to be optimal for a proper wettability and cell survival [ 78 , 79 , 80 , 81 ]. This translates into an improved future protein adsorption and cell adhesion and proliferation on a given sample surface, leading to an augmented biological response [ 82 ].…”

Gallium containing bioactive materials: A review of anticancer, antibacterial, and osteogenic properties

“…Stan et al [ 153 ] used the radio-frequency magnetron sputtering (RF-MS) method for coating titanium surfaces with Ga and Cu doped bioactive glass, using the FastOs®BG alkali-free glass composition. The glass coating did not show any cytotoxic behavior and served as an efficient antibacterial agent against S. aureus strain [ 153 ].…”