Cobalt Ferrite Synthesized Using a Biogenic Sol-Gel Method for Biomedical Applications.

Cancer is one of the leading causes of death worldwide. Conventional treatments such as surgery, chemotherapy, and radiotherapy have limitations and severe side effects. Magnetic hyperthermia (MH) is an alternative method that can be used alone or in conjunction with chemotherapy or radiotherapy to treat cancer. Cobalt ferrite particles were synthesized using an innovative biogenic sol-gel method with powder of coconut water (PCW). The obtained powders were subjected to heat treatments between 500 °C and 1100 °C. Subsequently, they were characterized by thermal, structural, magnetic, and cytotoxic analyses to assess their suitability for MH applications. Through X-ray diffraction and Raman spectroscopy, it was possible to confirm the presence of the pure phase of CoFe2O4 in the sample treated at 1100 °C, exhibiting a saturation magnetization of 84 emu/g at 300 K and an average grain size of 542 nm. Furthermore, the sample treated at 1100 °C showed a specific absorption rate (SAR) of 3.91 W/g, and at concentrations equal to or below 5 mg/mL, is non-cytotoxic, being the most suitable for biomedical applications.

Bioactive Glasses Containing Strontium or Magnesium Ions to Enhance the Biological Response in Bone Regeneration.

The non-surgical treatments are being required to reconstruct damaged tissue, prioritizing our body's natural healing process. Thus, the use of bioactive materials such as bioactive glass has been studied to support the repair and restoration of hard and soft tissue. Thus, in this work Bioglass 45S5 was developed, adding 1 and 2%mol of SrO or MgO and the physical and biological properties were evaluated. The addition of MgO and SrO at the studied concentrations promoted the slight increase in non-bridging oxygens number, observed through the temperature shift in phase transitions to lower values compared to Bioglass 45S5. The insertion of the ions also showed a positive effect on Saos-2 cell viability, decreasing the cytotoxic of Bioglass 45S5. Besides the Ca/P ratio on the pellets surface demonstrating no evidence of higher reactivity between Bioglass 45S5 and Bioglass with Sr and Mg, micrographs show that at 24 h the Ca/P rich layer is denser than in Bioglass 45S5 after the contact with simulated body fluid. The samples with Sr and Mg show a higher antibacterial effect compared to Bioglass 45S5. The addition of the studied ions may benefit the biological response of Bioglass 45S5 in dental applications as scaffolds or coatings.

Antibacterial Biomaterial Based on Bioglass Modified with Copper for Implants Coating.

Biofilm-related implant infections pose a substantial threat to patients, leading to inflammation in the surrounding tissue, and often resulting in implant loss and the necessity for additional surgeries. Overcoming this implantology challenge is crucial to ensure the success and durability of implants. This study shows the development of antibacterial materials for implant coatings by incorporating copper into 45S5 Bioglass®. By combining the regenerative properties of Bioglass® with the antimicrobial effects of copper, this material has the potential to prevent infections, enhance osseointegration and improve the long-term success of implants. Bioglasses modified with various concentrations of CuO (from 0 to 8 mol%) were prepared with the melt-quenching technique. Structural analysis using Raman and FTIR spectroscopies did not reveal significant alterations in the bioglasses structure with the addition of Cu. The antibacterial activity of the samples was assessed against Gram-positive and Gram-negative bacteria, and the results demonstrated significant inhibition of bacterial growth for the bioglass with 0.5 mol% of CuO. Cell viability studies indicated that the samples modified with up to 4 mol% of CuO maintained good cytocompatibility with the Saos-2 cell line at extract concentrations up to 25 mg/mL. Furthermore, the bioactivity assessment demonstrated the formation of a calcium phosphate (CaP)-rich layer on the surfaces of all bioglasses within 24 h. Our findings show that the inclusion of copper in the bioglass offers a significant enhancement in its potential as a coating material for implants, resulting in notable advancements in both antibacterial efficacy and osteointegration properties.

Bioactive Glass Modified with Zirconium Incorporation for Dental Implant Applications: Fabrication, Structural, Electrical, and Biological Analysis.

Implantology is crucial for restoring aesthetics and masticatory function in oral rehabilitation. Despite its advantages, certain issues, such as bacterial infection, may still arise that hinder osseointegration and result in implant rejection. This work aims to address these challenges by developing a biomaterial for dental implant coating based on 45S5 Bioglass® modified by zirconium insertion. The structural characterization of the glasses, by XRD, showed that the introduction of zirconium in the Bioglass network at a concentration higher than 2 mol% promotes phase separation, with crystal phase formation. Impedance spectroscopy was used, in the frequency range of 102-106 Hz and the temperature range of 200-400 K, to investigate the electrical properties of these Bioglasses, due to their ability to store electrical charges and therefore enhance the osseointegration capacity. The electrical study showed that the presence of crystal phases, in the glass ceramic with 8 mol% of zirconium, led to a significant increase in conductivity. In terms of biological properties, the Bioglasses exhibited an antibacterial effect against Gram-positive and Gram-negative bacteria and did not show cytotoxicity for the Saos-2 cell line at extract concentrations up to 25 mg/mL. Furthermore, the results of the bioactivity test revealed that within 24 h, a CaP-rich layer began to form on the surface of all the samples. According to our results, the incorporation of 2 mol% of ZrO2 into the Bioglass significantly improves its potential as a coating material for dental implants, enhancing both its antibacterial and osteointegration properties.

Nanostructured LiFe5O8 by a Biogenic Method for Applications from Electronics to Medicine.

The physical properties of the cubic and ferrimagnetic spinel ferrite LiFe5O8 has made it an attractive material for electronic and medical applications. In this work, LiFe5O8 nanosized crystallites were synthesized by a novel and eco-friendly sol-gel process, by using powder coconut water as a mediated reaction medium. The dried powders were heat-treated (HT) at temperatures between 400 and 1000 °C, and their structure, morphology, electrical and magnetic characteristics, cytotoxicity, and magnetic hyperthermia assays were performed. The heat treatment of the LiFe5O8 powder tunes the crystallite sizes between 50 nm and 200 nm. When increasing the temperature of the HT, secondary phases start to form. The dielectric analysis revealed, at 300 K and 10 kHz, an increase of ε' (≈10 up to ≈14) with a tanδ almost constant (≈0.3) with the increase of the HT temperature. The cytotoxicity results reveal, for concentrations below 2.5 mg/mL, that all samples have a non-cytotoxicity property. The sample heat-treated at 1000 °C, which revealed hysteresis and magnetic saturation of 73 emu g-1 at 300 K, showed a heating profile adequate for magnetic hyperthermia applications, showing the potential for biomedical applications.

Electrospun composite cellulose acetate/iron oxide nanoparticles non-woven membranes for magnetic hyperthermia applications.

In the present work composite membranes were produced by combining magnetic nanoparticles (NPs) with cellulose acetate (CA) membranes for magnetic hyperthermia applications. The non-woven CA membranes were produced by electrospinning technique, and magnetic NPs were incorporated by adsorption at fibers surface or by addition to the electrospinning solution. Therefore, different designs of composite membranes were obtained. Superparamagnetic NPs synthesized by chemical precipitation were stabilized either with oleic acid (OA) or dimercaptosuccinic acid (DMSA) to obtain stable suspensions at physiological pH. The incorporation of magnetic NP into CA matrix was confirmed by scanning and transmission electron microscopy. The results showed that adsorption of magnetic NPs at fibers' surface originates composite membranes with higher heating ability than those produced by incorporation of magnetic NPs inside the fibers. However, adsorption of magnetic NPs at fibers' surface can cause cytotoxicity depending on the NPs concentration. Tensile tests demonstrated a reinforcement effect caused by the incorporation of magnetic NPs in the non-woven membrane.

Local nanoelectromechanical properties of multiferroics Gd-doped BiFeO3-BaTiO3 solid solution.

Bi(1-x-y)GdxBayFe(1-y)TiyO3 (x = 0.1 and y = 0.1, 0.2, 0.3) solid solutions have been prepared via solid state reaction method with the aim to obtaining magnetoelectric coupling (i.e., linear relation between magnetization and electric field) at room temperature. Optimum calcination and sintering strategies for obtaining pure perovskite phase, high density ceramics and homogeneous microstructures have been determined. The maximum ferroelectric transition temperature (Tc) of this system was 150-170 degrees C with the dielectric constant peak of 2300 at 100 kHz for y = 0.1. Well saturated piezoelectric loops were observed for all composition indicating room temperature ferroelectricity. Hardness and Young's modulus decrease with depth and with increasing concentration y.