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 ${\epsilon }^{\prime }$ (≈10 up to ≈14) with a $tan$$\delta$ 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.

Several problems and limitations faced in the treatment of many diseases can be overcome by using controlled drug delivery systems (DDS), where the active compound is transported to the target site, minimizing undesirable side effects. In situ-forming hydrogels that can be injected as viscous liquids and jellify under physiological conditions and biocompatible clay nanoparticles have been used in DDS development. In this work, polymer–clay composites based on Pluronics (F127 and F68) and nanoclays were developed, aiming at a biocompatible and injectable system for long-term controlled delivery of methylene blue (MB) as a model drug. MB release from the systems produced was carried out at 37 °C in a pH 7.4 medium. The Pluronic formulation selected (F127/F68 18/2 wt.%) displayed a sol/gel transition at approx. 30 °C, needing a 2.5 N force to be injected at 25 °C. The addition of 2 wt.% of Na116 clay decreased the sol/gel transition to 28 °C and significantly enhanced its viscoelastic modulus. The most suitable DDS for long-term application was the Na116-MB hybrid from which, after 15 days, only 3% of the encapsulated MB was released. The system developed in this work proved to be injectable, with a long-term drug delivery profile up to 45 days.

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.

Electrospun membranes are compact structures with small pore sizes that hinder cell infiltration, resulting in membranes with cells attached only to the external surface rather than throughout the entire volume. Thus, there is a need to increase the pore size of electrospun membranes maintaining their structural similarity to the extracellular matrix. In this work, we used glucose crystals embedded in polyethylene oxide (PEO) fibers to create large pores in poly(lactic acid) (PLA) electrospun membranes to allow for cellular infiltration. The PEO fibers containing glucose crystals of different sizes (>50, 50–100 and 100–150 μm) and in varying concentrations (10, 15 and 20 %) were co-electrospun with PLA fibers and subsequently leached out using distilled water. PLA fibrous membranes without glucose crystals were also produced as controls. The membranes were examined for their morphology, mechanical properties, and potential to support the proliferation of fibroblasts. In addition, the immune response to the membranes was evaluated using monocyte-derived macrophages. The glucose crystals were uniformly distributed in the PLA membranes and their removal created open pores without collapsing the structure. Although a reduced Young's modulus was observed for membranes produced using higher glucose crystal concentrations and larger crystal sizes, the structural integrity remained intact, and the values are still suitable for tissue engineering. In vitro results showed that the scaffolds supported the adhesion and proliferation of fibroblasts and the pores created in the PLAmembranes were large enough for fibroblasts infiltration and colonization of the entire scaffold without inducing an inflammatory response.