Cu-Releasing Bioactive Glass Coatings and Their in Vitro Properties

Abstract

Bioactive glasses are well-known materials suitable for bone-related applications thanks to their biocompatibility and osteoconductivity. In order to improve their in vivo performance, the modification of the glass composition by adding ions with specific biological functions is required. As copper (Cu) possesses antibacterial properties, in this study, 5 wt % of CuO has been added to the 45S5 bioactive glass composition. The investigation of the effect of the Cu-containing bioactive glass on cellular behavior has revealed that the presence of Cu induces an early differentiation of human mesenchymal stem cells through osteoblast phenotype, promotes the expression of anti-inflammatory interleukin, and reduces proinflammatory interleukin expression. With the aim to produce coatings with antibacterial properties, the Cu-containing bioactive glass was used as the target material for the pulsed laser deposition (PLD) of bioactive thin films. PLD experiments were carried out at different substrate temperatures to study the effect on the film’s characteristics. All of the films are compact, crack-free, and characterized by a rough morphology and good wettability. The in vitro bioactivity was demonstrated by the apatite growth on the coating surface, after soaking in simulated body fluid, revealed by Raman spectroscopy and scanning electron microscopyenergy dispersive X-ray analyses. The antibacterial study proved that the material showed more effective activity against three Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli, Salmonella enterica) rather than against Gram-positive bacteria (Staphylococcus aureus).

Advances in Antibacterial Functionalized Coatings on Mg and Its Alloys for Medical Use—A Review

“…Metallic oxides have also been demonstrated to have antibacterial capabilities. Rau et al added 5 wt.% CuO into bioactive glass in their study and found that the CuO-contained material showed excellent antibacterial abilities, and the antibacterial abilities revealed were more effective against Gram-negative bacteria (Pseudomonas aeruginosa, Escherichia coli, and Salmonella enterica) rather than against Gram-positive bacteria (Staphylococcus aureus) [68].…”

Borate and Silicate Bioactive Glass Coatings Prepared by Nanosecond Pulsed Laser Deposition

“…To obtain crystalline films, nanosecond PLD deposition is usually performed by the heating of the substrate or by using a buffer gas [41,44,45], so we can expect that also the deposited films are amorphous. We deposited the films at room temperature since it was demonstrated that amorphous materials show superior solubility in biological or simulated biological fluid media and are characterized by an increased bioactivity with respect to crystalline materials [8,9,29,46].…”

“…No antibacterial effects can be expected for silicate glass films and, probably, the absence of these properties also for borate glass films can be imputed to the amount of boron released by the coatings, which could be too low to inhibit bacterial growth. Therefore, if the aim is to deposit thin bioactive films that also present antimicrobial effects, the addition of specific ions in the glass composition, such as Ag, Zn or Cu, is advisable [9,28,30,51].…”

“…However, it is not osteogenic; therefore, the osteointegration takes place over a longer time, during which the eventual occurrence of shift movements between the implant and the host bone could lead to the formation of a fibrous capsule around the implant surface and its consequent failure may occur. In order to increase the chances of successful bone-related implant procedures, the modification of the Ti surface by coating it with a bioactive material is advisable [4][5][6][7][8][9]. In this way the optimal bulk mechanical properties are preserved, and the implant surface is more suitable to provide a better osteointegration.…”

“…Recently, several bioactive glasses [9,[38][39][40] have been successfully deposited by PLD. Ma et al [38] obtained, by PLD, Magnesium-containing bioactive glass coatings on Ti-6Al-4V that demonstrated higher corrosion resistance with respect to the uncoated substrates and film bioactivity by in vitro assay.…”