BIOACTIVITY ANALYISIS OF RADIO-OPAQUE BIOGLASS/BISMUTH OXIDE COATINGS DEPOSITED BY THERMAL SPRAY

This contribution presents the bioactivity analysis of thermally sprayed Bi₂O₃ modified bioglass 45s5 (BG) coatings with radio-opacity functionalities. BG was fabricated by the melting and fast quenching method using the following stoichiometry: 45 wt. % SiO₂, 24.5 CaO wt. %, 24.5 wt. % Na₂O and 6 wt. % P₂O₅. During the preparation, Bi₂O₃ was added from 1 to 20 wt. %, in 5 wt. % intervals seeking for the optimal content that increases the radio-opacity avoiding major influence on the BG structure. The radio-opaque BG composition, transition temperatures and structure were determined by X-ray fluorescence (XRF), differential scanning calorimetry (DSC), X-ray diffraction (XRD). The radio-opacity characteristics were determined following the ISO 13116:2014 norm. Thereafter, glass powder was deposited in stainless steel substrates by plasma spray. Commercial BG was also deposited for comparative purposes. The coatings morphology, thickness and microstructure were analyzed by scanning electron microscopy (SEM) micrographs. Finally, bioactivity was studied by soaking the samples in simulated body fluid (SBF), during 3, 7, 14 and 21 days. This bioactivity was evaluated by the growth kinetics of the carbonate-apatite layer of the coating surface after the immersion, using SEM micrographs, XRD analysis and ion measurements on the SBF by ICP-OES.