Nanoparticles (NPs) of magnesium hydroxide appear to be an exceptional nanomaterial due to its biocompatibility and low toxicity. However, the mechanism by which the NPs act in the organism has been very difficult to study. In order to contribute to that challenge, in this work magnesium hydroxide was functionalised with organic fluorophores allowing the material to be traced during an in-vivo experiment. Magnesium hydroxide NPs were obtained by the co-precipitation method and analysed by TEM (Transmission electron microscopy), XRD (x-ray diffraction), Raman spectroscopy (RS) and FTIR (Fourier transform infrared spectroscopy). The effects of reaction time, agitation and stoichiometric ratios of the reagents (MgCl 2 :NaOH) on the NPs characteristics were studied. Mg(OH) 2 NPs with average sizes below 65±26 nm were obtained with hexagonal, circular or irregular platelet-shape. NPs with an average size of 41±12 nm were functionalised with curcumin and rhodamine using (3-aminopropyl)-triethoxysilane (APTES) as a coupling agent. It was observed the positive effect of the addition of APTES keeping the Mg(OH) 2 NPs dispersed. Moreover, it was found that incorporating APTES as a binding agent with curcumin quenched the fluorescence of curcumin on nanoparticles.

In this work, anodic oxide layers on the surface of an AZ31 magnesium alloy were obtained by plasma electrolytic oxidation (PEO) process under low frequency pulsed current. For this, electrolytical solutions containing hexamethylenetetramine and sodium fluoride were used. The morphology and chemical composition of formed coatings were examined by scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), Fourier transform infrared spectroscopy (FTIR) and X-ray diffraction (XRD). Also, salt spray test, hydrogen evolution and electrochemical tests (potentiodynamic polarization and electrochemical impedance spectroscopy) were conducted in order to study the corrosion behavior of the coated samples. It was found that the use of low frequency pulsed current for the PEO process reduces the film porosity and increases its thickness, compared with PEO films obtained by continuous anodization. The effect of the pulsed current signal was also analyzed for a two steps PEO process, observing changes in the morphological characteristics of the coatings which allow a better corrosion according electrochemical tests (short term corrosion measurements). However, long term tests results as hydrogen evolution and salt spray tests, indicated the opposite. Both the film porosity and thickness were affected by either the pulsing of the current or the use of a two-step process.

Magnesium-based nanoparticles have shown promise in regenerative therapies in orthopedics and the cardiovascular system. Here, we set out to assess the influence of differently functionalized Mg nanoparticles on the cellular players of wound healing, the first step in the process of tissue regeneration. First, we thoroughly addressed the physicochemical characteristics of magnesium hydroxide nanoparticles, which exhibited low colloidal stability and strong aggregation in cell culture media. To address this matter, magnesium hydroxide nanoparticles underwent surface functionalization by 3-aminopropyltriethoxysilane (APTES), resulting in excellent dispersible properties in ethanol and improved colloidal stability in physiological media. The latter was determined as a concentration- and time-dependent phenomenon. There were no significant effects on THP-1 macrophage viability up to 1.500 μg/mL APTES-coated magnesium hydroxide nanoparticles. Accordingly, increased media pH and Mg 2+ concentration, the nanoparticles dissociation products, had no adverse effects on their viability and morphology. HDF, ASCs, and PK84 exhibited the highest, and HUVECs, HPMECs, and THP-1 cells the lowest resistance toward nanoparticle toxic effects. In conclusion, the indicated high magnesium hydroxide nanoparticles biocompatibility suggests them a potential drug delivery vehicle for treating diseases like fibrosis or cancer. If delivered in a targeted manner, cytotoxic nanoparticles could be considered a potential localized and specific prevention strategy for treating highly prevalent diseases like fibrosis or cancer. Looking toward the possible clinical applications, accurate interpretation of in vitro cellular responses is the keystone for the relevant prediction of subsequent in vivo biological effects.

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