Porous magnetic Fe3O4/bioactive glass–ceramic (CaO-SiO2-P2O5-MgO) scaffold with enhanced self-heating ability for hyperthermia treatment of bone tumor—an in vitro study

Influence of zirconium dioxide (ZrO2) and magnetite (Fe3O4) additions on the structural, electrical, and biological properties of Bioglass® for metal implant coatings

Background

The growing need for durable implants, driven by aging populations and increased trauma cases, highlights challenges such as limited osseointegration and biofilm formation. 45S5 Bioglass® has shown promise due to its bioactivity, antimicrobial properties, and ability to enhance osseointegration through electrical polarization. This study investigates the effects of incorporating different concentrations of ZrO2 and Fe3O4 into 45S5 Bioglass® to enhance its electrical and biological properties.

Methods

Raman analysis was used to evaluate how these oxides influenced the amount of non-bridging oxygens (NBOs) and glass network connectivity. Electrical characterization was performed using impedance spectroscopy to measure conductivity and ion mobility. Antibacterial activity was assessed using the agar diffusion method, and bioactivity was evaluated through simulated body fluid (SBF) immersion tests.

Results

The results revealed that bioglasses containing ZrO2 exhibited higher NBO content compared to Fe3O4, leading to improved electrical and biological properties. ZrO2, particularly at 2 mol%, significantly enhanced conductivity, antibacterial activity, and bioactivity. In contrast, Fe3O4 reduced both antibacterial activity and bioactivity.

Conclusion

The findings demonstrate that ZrO2 addition improves the electrical and biological performance of 45S5 Bioglass®, making it a promising candidate for durable implants. Fe3O4, however, showed limited benefits.

Impact of Iron Oxide Phases on the Magnetic Induction Heating Capacity of Mesoporous 45SiO2-16.5CaO-24.5Na2O-6P2O5-8Fe3O4 Glass-Ceramics

Sol-gel-based mesoporous 45SiO2-16.5CaO-24.5Na2O-6P2O5-8Fe3O4 bioglass-ceramics were obtained by substituting magnetite nanoparticles for CaO in a 45SiO2-24.5CaO-24.5Na2O-6P2O5 bioglass composition. To enhance the dissolution of the precursors and to vary the crystalline phases, the as-synthesized ceramic powders were processed for 1 h each at temperatures (TA) between 550 and 700 °C. A gradual decline in the saturation magnetization with an increase in TA was observed, which is linked to the gradual conversion of magnetite into hematite at different TA > 550 °C. All of the processed samples indicated a hydroxyapatite surface layer formation in in vitro tests. Aqueous solutions of the ceramic processed at 600 °C exhibited superior magnetic induction capacity. Thus, the substitution of magnetite nanoparticles for CaO in the base composition, coupled with appropriate heat treatment, results in a promising bioactive glass-ceramic for magnetic hyperthermia treatment of deep-rooted cancer cells.

The Effect of Iron Oxide Insertion on the In Vitro Bioactivity, and Antibacterial Properties of the 45S5 Bioactive Glass

The aging population and increasing incidence of trauma among younger age groups have heightened the increasing demand for reliable implant materials. Effective implant materials must demonstrate rapid osseointegration and strong antibacterial properties to ensure optimal patient outcomes and decrease the chance of implant rejection. This study aims to enhance the bone-implant interface by utilizing 45S5 bioglass modified with various concentrations of Fe3O4 as a coating material. The effect of the insertion of Fe3O4 into the bioglass structure was studied using Raman spectroscopy which shows that with the increase in Fe3O4 concentration, new vibration bands associated with Fe-related structural units appeared within the sample. The bioactivity of the prepared glasses was evaluated using immersion tests in simulated body fluid, revealing the formation of a calcium phosphate-rich layer within 24 h on the samples, indicating their potential for enhanced tissue integration. However, the sample modified with 8 mol% of Fe3O4 showed low reactivity, developing a calcium phosphate-rich layer within 96 h. All the bioglasses showed antibacterial activity against the Gram-positive and Gram-negative bacteria. The modified bioglass did not present significant antibacterial properties compared to the bioglass base.