Multifunctional polymeric coatings containing drug delivery vehicles can play a key role in preventing/reducing biofilm formation on implant surfaces. Their requirements are biocompatibility, good adhesion, and controllable drug release. Although cellulose acetate (CA) films and membranes are widely studied for scaffolding, their applications as a protective coating and drug delivery vehicle for metal implants are scarce. The reason is that adhesion to stainless steel (SS) substrates is non-trivial. Grinding SS substrates enhances the adhesion of dip-coated CA films while the adhesion of electrospun CA membranes is improved by an electrosprayed chitosan intermediate layer. PMMA microcapsules containing daptomycin have been successfully incorporated into CA films and fibres. The released drug concentration of 3 x10-3 mg/mL after 120 minutes was confirmed from the peak luminescence intensity under UV radiation of simulated body fluid (SBF) after immersion of the fibres.

Continuous wave terahertz (CW THz) imaging, is a variant of terahertz imaging that has been gaining scientific
and technological relevance in multiple areas. In this paper the fundamental phenomena of CW THz were
studied and a mathematical model was developed that successfully describes the Fabry–Perot interference for
such a system, opening the possibility for measurement of thicknesses and surface curvatures. The capabilities
of the system were tested using different types of defects, such as voids, water infiltrations and thin metallic
wires. The interactions between different materials, features and the radiation beam were numerically studied
using finite element method and the results agreed with the experiments. By comparing the results with other
Non-Destructive Testing methods, it was found that CW THz imaging is particularly interesting to image water
infiltrations and composite materials that incorporate conductive wires.

Design, research, and development of new and improved smart multifunctional devices is one of the main topics in the advanced functional materials agenda for the next decade. Smart materials that can be triggered by external stimuli are seen with high potential for innovative treatments and improved drug delivery systems by regulatory agencies like the FDA and EMA. The incorporation of magnetic nanostructures into complex systems produces multifunctional devices that can be spatiotemporally controlled by an external magnetic field. These magneto-responsive devices can be used for a multitude of biomedical applications, from diagnostic to the treatment of tumors, and are actively being developed and tested for cancer theranostics. Herein, we review the development of magneto-responsive devices for cancer theranostics, starting from the most straightforward architecture, single nanoparticles. We give some theoretical concepts about the design and production of such systems while providing a critical review of applications in clinical practice. Naturally, the review evolves to more complex architectures, from one-dimensional to three-dimensional magneto-responsive systems, demonstrating higher complexity and multifunctionality, and consequently, higher interest for clinical practice. The review ends with the main challenges in the design and engineering of magneto-responsive devices for cancer theranostics and future trends in this biomedical field.

Electronic controlled drug release from fibres was studied using ibuprofen as a model drug, one of the most popular analgesics, to impregnate gauze and cellulose acetate (CA) membranes. Conductivity in the range of 1–10 mS cm−1 was obtained in polypyrrole (Ppy) functionalised gauze and CA fibres, providing voltage-controlled drug release in a system consisting of Ppy/Ibuprofen/Ppy membranes and an Ag electrode. SEM images evidenced the Ppy adhesion to fibres and Micro Raman spectra proved drug incorporation and release. A small wound adhesive built with these membranes retains ibuprofen at 1.5 V and quickly releases it when −0.5 V is applied.

The delivery of multiple anti-cancer agents holds great promise for better treatments. The present work focuses on developing multifunctional materials for simultaneous and local combinatory treatment: Chemotherapy and hyperthermia. We first produced hybrid microgels (MG), synthesized by surfactant-free emulsion polymerization, consisting of Poly (N-isopropyl acrylamide) (PNIPAAm), chitosan (40 wt.%), and iron oxide nanoparticles (NPs) (5 wt.%) as the inorganic component. PNIPAAm MGs with a hydrodynamic diameter of about 1 μm (in their swollen state) were successfully synthesized. With the incorporation of chitosan and NPs in PNIPAAm MG, a decrease in MG diameter and swelling capacity was observed, without affecting their thermosensitivity. We then sought to produce biocompatible and mechanically robust membranes containing these dual-responsive MG. To achieve this, MG were incorporated in poly (vinyl pyrrolidone) (PVP) fibers through colloidal electrospinning. The presence of NPs in MG decreases the membrane swelling ratio from 10 to values between 6 and 7, and increases the material stiffness, raising its Young modulus from 20 to 35 MPa. Furthermore, magnetic hyperthermia assay shows that PVP-MG-NP composites perform better than any other formulation, with a temperature variation of about 1 °C. The present work demonstrates the potential of using multifunctional colloidal membranes for magnetic hyperthermia and may in the future be used as an alternative treatment for cancer.

Engineering drug delivery systems (DDS) aim to release bioactive cargo to a specific site within the human body safely and efficiently. Hydrogels have been used as delivery matrices in different studies due to their biocompatibility, biodegradability, and versatility in biomedical purposes. Microparticles have also been used as drug delivery systems for similar reasons. The combination of microparticles and hydrogels in a composite system has been the topic of many research works. These composite systems can be injected in loco as DDS. The hydrogel will serve as a barrier to protect the particles and retard the release of any bioactive cargo within the particles. Additionally, these systems allow different release profiles, where different loads can be released sequentially, thus allowing a synergistic treatment. The reported advantages from several studies of these systems can be of great use in biomedicine for the development of more effective DDS. This review will focus on in situ injectable microparticles in hydrogel composite DDS for biomedical purposes, where a compilation of different studies will be analysed and reported herein.

The present paper regards the preparation and characterization of Pluronic F127 + F68/water/poly (ε-caprolactone) microcapsules (MCs) composite systems for tissue repair. The first part of the work relates to the production of poly(ε-caprolactone) (PCL) MCs via water-in-oil-in-water (W/O/W) double emulsion system combined with solvent evaporation method. The study of different process parameters in the final MCs characteristics and their drug release profile is herein reported. Different percentages of PCL, emulsion stabilizer, and volume proportions of the emulsion constituents have been tested, leading to considerable differences in the MCs size distributions. The selected MCs, containing an aqueous solution of methylene blue (MB) as a model drug, were then used to fill a Pluronic F127 + F68/water system leading to the final composite system (5 and 10 wt % MB loaded PCL MCs). The composite systems were characterised in the second part of the work in terms of its rheological behaviour and drug release performance. They were found to gellify at 30 °C, and present an extended drug release to a total of 18 days. The models that best define the release profiles were also studied, with the release of MB occurring mostly by Fick diffusion and polymer chain relaxation. Pluronic F127 + F68/water/poly (ε-caprolactone) MCs composite system is shown to be a promising injectable system, with two different drug release rates, for tissue repair.

Cancer remains as one of the major causes of mortality worldwide. Recent advances in nanoparticles based therapy mark a new era on cancer treatment. Many groups have investigated biological/physical effects of nanoparticles on tumour cells and how these vary with physical parameters such as particle size, shape, concentration and distribution. Magnetic hyperthermia (MHT) can be an alternative or an add-value therapy with demonstrated effectiveness. MHT uses magnetic nanoparticles, which can be directly applied to the tumour, where, by applying an external ac magnetic field, will promote a localized temperature increment that can be controlled.

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.

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.

High-entropy alloys (HEAs) have been around since 2004. The breakthroughs in this field led to several potential applications of these alloys as refractory, structural, functional, and biomedical materials. In this work, a short overview on the concept of high-entropy alloys is provided, as well as the theoretical design approach. The special focus of this review concerns one novel class of these alloys: biomedical high-entropy alloys. Here, a literature review on the potential high-entropy alloys for biomedical applications is presented. The characteristics that are required for these alloys to be used in biomedical-oriented applications, namely their mechanical and biocompatibility properties, are discussed and compared to commercially available Ti6Al4V. Different processing routes are also discussed.