Influence of SPION Surface Coating on Magnetic Properties and Theranostic Profile.

This study aimed to develop multifunctional nanoplatforms for both cancer imaging and therapy using superparamagnetic iron oxide nanoparticles (SPIONs). Two distinct synthetic methods, reduction-precipitation (MR/P) and co-precipitation at controlled pH (MpH), were explored, including the assessment of the coating's influence, namely dextran and gold, on their magnetic properties. These SPIONs were further functionalized with gadolinium to act as dual T1/T2 contrast agents for magnetic resonance imaging (MRI). Parameters such as size, stability, morphology, and magnetic behavior were evaluated by a detailed characterization analysis. To assess their efficacy in imaging and therapy, relaxivity and hyperthermia experiments were performed, respectively. The results revealed that both synthetic methods lead to SPIONs with similar average size, 9 nm. Mössbauer spectroscopy indicated that samples obtained from MR/P consist of approximately 11-13% of Fe present in magnetite, while samples obtained from MpH have higher contents of 33-45%. Despite coating and functionalization, all samples exhibited superparamagnetic behavior at room temperature. Hyperthermia experiments showed increased SAR values with higher magnetic field intensity and frequency. Moreover, the relaxivity studies suggested potential dual T1/T2 contrast agent capabilities for the coated SPpH-Dx-Au-Gd sample, thus demonstrating its potential in cancer diagnosis.

Fabrication of a biodegradable and cytocompatible magnesium/nanohydroxyapatite/fluorapatite composite by upward friction stir processing for biomedical applications.

Biodegradable magnesium (Mg)-based metal matrix composites are promising candidates for orthopaedic applications since magnesium is an abundant mineral in the human body. To improve the bioactivity and cytocompatibility of these Mg composites, hydroxyapatite nanoparticles (HAP) and fluorapatite (FA) microparticles synthesised by a citrate-derived hydrothermal method were introduced into a Mg matrix. These innovative Mg/HAP/FA composites were produced by multi-pass upward friction stir processing (UFSP). Microstructural observation and Micro-CT reconstruction of the composite revealed that HAP and FA particles are well dispersed in the Mg matrix and the magnesium grain size was significantly reduced after the UFSP process. The in vitro bioactivity behaviour of UFSP processed Mg/HAP/FA composites was investigated in simulated body fluid. The results revealed the formation of a fluoride-rich apatite layer on the composites, which was attributed to the release of fluoride ions from the composite and their precipitation in a different configuration. Moreover, cytocompatibility results revealed that the presence of FA particles, together with HAP nanoparticles, were able to favour osteoblasts-biomaterial interaction.

3D-printed platform multi-loaded with bioactive, magnetic nanoparticles and an antibiotic for re-growing bone tissue.

Polymeric platforms obtained by three-dimensional (3D) printing are becoming increasingly important as multifunctional therapeutic systems for bone treatment applications. In particularly, researchers aim to control bacterial biofilm on these 3D-platforms and enhance re-growing bone tissue, at the same time. This study aimed to fabricate a 3D-printed polylactic acid platform loaded with hydroxyapatite (HA), iron oxide nanoparticles (IONPs) and an antibiotic (minocycline) with tuneable properties and multistimuli response. IONPs were produced by a facile chemical co-precipitation method showing an average diameter between 11 and 15 nm and a superparamagnetic behaviour which was preserved when loaded into the 3D-platforms. The presence of two types of nanoparticles (IONPs and HA) modify the nanomorphological/nanotopographical feature of the 3D-platforms justifying their adequate bioactivity profile and in vitro cellular effects on immortalized and primary osteoblasts, including cytocompatibility and increased osteogenesis-related gene expression (RUNX2, BGLAP and SPP1). Disk diffusion assays and SEM analysis confirmed the effect of the 3D-platforms loaded with minocycline against Staphylococcus aureus. Altogether results showed that fabricated 3D-platforms combined the exact therapeutic antibiofilm dose of the antibiotic against S. aureus, with the enhanced osteogenic stimulation of the HA and IONPs nanoparticles which is a disruptive approach for bone targeting applications.