Bioactivity and mechanical behaviour of cobalt oxide-doped bioactive glass

Abstract

Bioactive glasses are materials capable of bonding implants to tissues. 45S5 Bio-glass R is one such material capable of bonding strongly to bone within 6 weeks. It develops a hydroxy-carbonate apatite layer on the implant that is chemically and crystallographically equivalent to the mineral phase of bone. However, it suffers from a mechanical weakness and low fracture toughness due to an amorphous glass network and is not suitable for load-bearing applications. In order to improve its mechanical strength and bioactivity, the present work explores the effects of cobalt oxide additions. Bioactivity of the glass samples was assessed through their hydroxyapatite formation ability by immersing them in the simulated body fluid for different soaking periods. The formation of hydroxyapatite was confirmed by Fourier transform infrared spectrometry, pH measurement and microstructure evaluation through scanning electron microscopy. Densities and mechanical properties of the samples were found to increase considerably with an increase in the concentration of cobalt oxide.

Assessment of nickel oxide substituted bioactive glass-ceramic on in vitro bioactivity and mechanical properties

“…The authors found that there was an excellent agreement between metal-oxygen (M-O) correlation obtained for Ni by isotopic substitution and Ni/Co data sets by isomorphic substitution method which confirmed that both Ni 2+ and Co 2+ ion were isostructural in the bioactive glasses. [4,39,40] in an earlier investigation had also shown that the addition of cobalt oxide up to 2.0 wt% in 45S5 bioactive glass-ceramic has resulted in an increase in density and compressive strength of their samples due to formation Co-O-Si bonds. Azevedo et al [26] had also performed the 29 Si MAS-NMR to determine the role of Co 2+ ion in the silicate glass structure and reported the dual role of Co 2+ as an intermediate and modifier in their bioglass samples depending upon its concentration like Mg 2+ , Ca 2+ and Zn 2+ ions.…”

Development of Zirconia Substituted 1393 Bioactive Glass for Orthopaedic Application

“…Kokubo and his teams developed Simulated Body Fluid (SBF) which has similar inorganic ion concentrations to those of human extracellular fluid 22,[29][30][31] . The ion concentrations of SBF are given on Table. 2.…”

“…12 2+ and Na + ions from the sample surface 22,23,25,26 . The sample number G-4 with higher zirconia content was found to show maximum pH value may be due to high rate of dissolution as compared to base sample G-1.…”

“…The total range of density is found to be from 2.44 g/ cm 3 to 2.495 g/cm 3 . The density of bioactive glass is directly proportional to the solidity of the configuration 22,23,25,26 . Here G-4 and G-5 glass are showing approximately same density which means these materials are suitable for making scaffolds for bone tissue engineering 47 .…”

“…In vitro evaluation has also shown that ZrO 2 is not cytotoxic [19][20][21] . Vyas et al, [22][23][24][25][26][27] in an earlier investigation had also shown that the addition of cobalt oxide and nickel oxide up to 0-2.0 wt% in 45S5 glass (BG) and glassceramic (BGC) has resulted an increase physicomechanical properties and bioactivity of their samples due to formation Co-O-Si and Ni-O-Si bonds. Tripathi et al, 28 have also found the characterization of Li 2 O, CaO, Al 2 O 3 , P 2 O 5 ,SiO 2 glasses as bioactive material and all the elastic moduli values were establish to increase with the increasing in Al 2 O 3 /Li 2 O ratio.…”