The bioactivity mechanism of magnetron sputtered bioglass thin films

Preferential sputtering in phosphate glass systems for the processing of bioactive coatings

“…The sputtering yield of the alkali metals was greater than the sputtering yields for the network forming phosphate, implying preferential sputtering of the network modifier ions. Berbecaru et al and Stan et al reported similar results whilst sputtering from silicate glass targets, with notably lower sputtering yields for silicon, and phosphorous, and higher sputtering yields for sodium, magnesium and calcium [25,29]. The relative changes from target to coating were reported by Berbecaru [29].…”

“…Berbecaru et al deposited a 0.5 μm thick bioactive glass coating (SiO 2 -40.5 CaO-32 P 2 O 5 -1.5 Na 2 O-9 MgO-17 mol%) on silicon substrates which were subsequently immersed for 30 days in SBF, and appeared to follow the stages of Hench's bioactivity theory, beginning with the solubility and degradation of the silicon network, followed by the formation of a calcium-phosphate apatite layer at the surface. A partially crystallised carbonated HA (CHA) layer appeared within the 30th day of testing [27,29]. The HA layer grew from 500 nm after 15 d with Ca:P ratio of 1.3 to 1200 nm by 30 d with a ratio of 1.77, indicating continuous calcium precipitation [27].…”

“…When bombarded with charged argon particles, atoms are preferentially ejected from a glass structure [25][26][27][28][29]37] a relationship termed relative sputtering yield. Sputtering yields are defined as the number of sputtered atoms/incident energetic ions; however, in relative terms, this refers to differential sputtering rates for individual elements, or elements within a compound.…”

Bioglass implant-coating interactions in synthetic physiological fluids with varying degrees of biomimicry

“…54 The slight deviation in the bands' maxima ( Figure 6A) with respect to a pure highly crystalline HA ( Figure 6D) indicated the biomineralization of an HA layer with structural faults (due to ionic substitutions with species or functional groups present in the SBF solution). 55 The occurrence of supplemental low-intensity bands was also signaled ( Figure 6A), and can be ascribed to the juxtaposition of the ν 2 bending mode of carbonate and vibrations typical of labile (HPO 4 ) 2-ions present in nonapatitic domains (peaking at 873 cm ) and to the symmetric stretching vibrations of Si−O bonds elicited in various environments (original BG film, silica-rich gel layer formed in the previous stages of bioactivity 17,56 ) centered at 819, 808, and 737 cm -1 . The integral area of the prominent phosphate asymmetric stretching band can be approximated with the thickness of HA films (Beer-Lambert law) chemically grown in vitro in simulated body media, and thus can be associated with one sample capacity of biomineralization.…”

Electrophoretic deposition of chitosan/Bioglass® and chitosan/Bioglass®/TiO2 composite coatings for bioimplants

“…Chitosan coatings have been obtained by cathodic electrophoretic deposition in previous research [8,9]. Bioactive glasses have excellent bioactivity and biocompatibility, they are used in several biomedical applications, for example non-load-bearing implants, bone cements, tissue engineering scaffolds, drug delivery systems, and bioactive coatings [10][11][12][13][14]. In particular, composite materials incorporating bioactive glasses are being considered promising for applications in biomedical coatings [7,[15][16][17].…”