Nanocomposites of magnetite (Fe3O4) and reduced graphene oxide (rGO) generate heat under an alternating magnetic field and therefore have potential applications as thermoseeds for cancer hyperthermia treatment. However, the properties of such nanocomposites as biomaterials have not been sufficiently well characterized. In this study, the osteoconductivity of Fe3O4-rGO nanocomposites of various compositions was evaluated in vitro in terms of their apatite-forming ability in simulated body fluid (SBF). Furthermore, the heat generation of the nanocomposites was measured under an alternating magnetic field. The apatite-forming ability in SBF improved as the Fe3O4 content in the nanocomposite was increased. As the Fe3O4 content was increased, the nanocomposite not only rapidly raised the surrounding temperature to approximately 100 °C, but the specific absorption rate also increased. We assumed that the ionic interaction between the Fe3O4 and rGO was enhanced and that Brown relaxation was suppressed as the proportion of rGO in the nanocomposite was increased. Consequently, a high content of Fe3O4 in the nanocomposite was effective for improving both the osteoconductivity and heat generation characteristics for hyperthermia applications.
Dense iron-doped akermanite ceramics with 0.3, 0.6 and 0.9 mol% of Fe3+ were synthesized via high-speed planetary ball milling and subsequently subjected to sintering at 1200 and 1250 °C. The aim of the current work was to investigate the effect of trivalent iron (Fe3+) in tuning the physicomechanical and in vitro biological properties of akermanite. The incorporation of Fe3+ into akermanite host and sintering at a high temperature of 1200 °C resulted in a synergistic effect in enhancing the sinterability and densification of akermanite ceramics. Although varying the Fe3+ content, it was found that similar densification and mechanical properties (i.e., diametral tensile strength, Vickers microhardness and fracture toughness) were observed for the doped ceramics at 1250 °C, indicating that this newly developed formulation is temperature-dependent. Fe3+-doped akermanite ceramics revealed greater in vitro bioactivity as compared to undoped akermanite, demonstrated by better coverage of needle-like apatite precipitates after 21 days of immersion in simulated body fluid. Additionally, Rat-1 cells cultured in direct contact with Fe3+-doped akermanite ceramics showed almost double levels of cell proliferation than their undoped counterpart on both 3 and 7 days of culture. Our finding suggests that 0.9Fe-AK ceramic is a suitable formulation to be considered for future bone substitute material as it provides sufficient mechanical strength as well as good bioactivity and the ability to encourage cell proliferation.
In present study, a new composition of glass-ceramic was synthesized based on the Na2O-CaO-SiO2-P2O5 glass system. Heat treatment of glass powder was carried out in 2 stages: 600 °C as the nucleation temperature and different temperature on crystallization at 850, 950 and 1000 °C. The glass-ceramic heat-treated at 950 °C was selected as bioactive filler in commercial PMMA bone cement; (PALACOS® LV) due to its ability to form 2 high crystallization phases in comparison with 850 and 1000 °C. The results of this newly glass-ceramic filled PMMA bone cement at 0-16 wt% of filler loading were compared with those of hydroxyapatite (HA). The effect of different filler loading on the setting properties was evaluated. The peak temperature during the polymerization of bone cement decreased when the liquid to powder (L/P) ratio was reduced. The setting time, however, did not show any trend when filler loading was increased. In contrast, dough time was observed to decrease with increased filler loading. Apatite morphology was observed on the surface of the glass-ceramic and selected cement after bioactivity test.