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Although the impact of local fluid dynamics in the biodegradation of magnesium is well known, currently no studies in the literature address the degradation effects of ocular vitreous on bioresorbable devices made of magnesium, which could be developed as drug delivery carriers. The aim of this study was to investigate the flow-induced corrosion mechanism of magnesium in an ophthalmological environment for future applications in ophthalmic drug delivery. To achieve this, experimental and computational methods were combined. Specifically, a CFD model was employed to design experimental conditions that replicate the ocular flow-induced shear stress (FISS) on manufactured magnesium samples. Pure Mg samples were tested in a bioreactor system capable of imposing the ocular CFD calculated values of FISS on the Mg samples' surface by varying the pump flow rate. Optimal flow rates for a range of different FISS values specific to the ophthalmological fluid dynamics affecting the device were indeed determined before running the experiments. After conducting customized corrosion tests, morphological observations and profilometric maps of the eroded surfaces of Mg samples were obtained using scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). These maps were then post-processed for the parametric evaluation of corrosion rates. Pre-existing localized superficial defects did affect the final corrosion pattern. SEM images and CLSM data confirmed a uniform corrosion mechanism, with corrosion rates of 1.9, 2.7, and 3.4 μm/day under different shear stress conditions (0, 0.01, and 0.032 Pa, respectively). More generally, uniform corrosion on pure Mg samples increased with higher FISS values, and at higher shear stress values (FISS = 0.032 Pa), a notable washing-out effect of the corrosion products was observed. The removal of corrosion products at higher shear stresses suggests that the dynamic ocular environment, influenced by saccadic movements, plays a significant role in the corrosion mechanism of pure magnesium. The corrosion rates determined in this study, in conjunction with clinical drug release requirements, are crucial for designing potential drug-release devices for ocular applications. [ABSTRACT FROM AUTHOR]

Bone scaffolding is a promising approach for the treatment of critical‐size bone defects. Hydroxyapatite can be used to produce highly porous scaffolds as it mimics the mineralized part of bone tissue, but its intrinsic brittleness limits its usage. Among 3D printing techniques, vat photopolymerization allows for the best printing resolution for ceramic materials. In this study, we implemented a Computed micro‐Tomography based Finite Element Model of a hydroxyapatite porous scaffold fabricated by vat photopolymerization. We used the model in order to predict the elastic and fracture properties of the scaffold. From the stress–strain diagram of a simulated compression test, we computed the stiffness and the strength of the scaffolds. We found that three morphometric features substantially affect the crack pattern. In particular, the crack propagation is not only dependent on the trabecular thickness but also depends on the slenderness and orientation of the trabeculae with respect to the load. The results found in this study can be used for the design of ceramic scaffolds with heterogeneous pore distribution in order to tailor and predict the compressive strength. [ABSTRACT FROM AUTHOR]

In this study, the mechanical properties of two classes of robocast glass scaffolds are obtained through Computed micro-Tomography (micro-CT) based Finite Element Modeling (FEM) with the specific purpose to explicitly account for the geometrical defects introduced during manufacturing. Both classes demonstrate a fiber distribution along two perpendicular directions on parallel layers with a 90 ∘ tilting between two adjacent layers. The crack pattern identified upon compression loading is consistent with that found in experimental studies available in literature. The finite element models have demonstrated that the effect of imperfections on elastic and strength properties may be substantial, depending on the specific type of defect identified in the scaffolds. In particular, micro-porosity, fiber length interruption and fiber detaching were found as key factors. The micro-pores act as stress concentrators promoting fracture initiation and propagation, while fiber detachment reduces the scaffold properties substantially along the direction perpendicular to the fiber plane. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Common clinical problems frequently place a significant stress on the clinical system, and the musculoskeletal system is particularly susceptible to aging and traumatic occurrences. New solutions are required to address significant unmet needs for patients who require bone-substitute implants to treat critical-size bone defects, including personalized solutions for better clinical outcomes, material advancements to ensure higher mechanical reliability without sacrificing bioactive and bioresorbable properties, and optimized manufacturing techniques for materials and products of high reliability and quality. The four-year ReBone Doctoral Network, funded by the Europe Horizon Marie Sklodowska programme, aims to train a new generation of researchers in an innovative and multidisciplinary optimization process to provide technologies for customized bone-substitute implants based on bioactive ceramics and cutting-edge additive manufacturing techniques, to address the health and societal burdens of trauma and bone diseases. MATERIALS and METHODS: A multidisciplinary network and training program have been planned in which ten doctoral candidates will jointly develop an innovative and integrated methodology to the design of personalized ceramic-based bone substitute implants. In order to achieve the purpose, a European network of partners and associated partners has been established encompassing diverse disciplines including biomechanics, clinics, materials engineering, mechano-biology, additive manufacturing technologies and mixed reality models for surgical planning simulations. Materials play a significant role in this project in terms of mechanical properties, bioactivity, biocompatibility, printing technology, and pertinent fidelity. Biologists, material engineers, bioengineers, and technology developers will collaborate to design and thoroughly characterize glass-ceramic based materials for the intended use. Four clinical cases of patients in the need of bone repair will be purposely selected with the aim to develop real-case scenarios of personalized design of bone-substitute implants. Clinical data will be used to create personalized multi-scale models of the implant at the organ level; concurrently, the design of device architecture, materials and parameters for manufacturing technology will be optimized to achieve improved implant outcome in terms of optimal mechanical performance in relationship to the shape and the anatomical location of the implant. RESULTS AND DISCUSSION: As a primary result, a consortium of nine European countries has been constituted and an up-to-date multidisciplinary training program has been set. Furthermore, ten interdisciplinary doctoral research projects have been drawn; ten Doctoral Candidates will undertake the above-mentioned research program in a multidisciplinary environment. Preliminary results achieved by the research institutes involved in the project in the area of ceramic materials development and characterization, additive manufacturing and biomechanics and a clinical research institute will constitute the solid background of the whole activity. CONCLUSIONS: The Europe Horizon Marie Sklodowska program funds the ReBone Doctoral Network, which addresses issues with bone-substitute implants for critical-size bone lesions. A variety of research fields will be addressed by the multidiscciplinary approach. Among these, technological and material development advancements are crucial and will serve as the foundation for the design of customized solutions. [ABSTRACT FROM AUTHOR]

Inkjet printing is a promising technology providing cost-effective method for processing various materials on deformable substrates. In this work, linear and serpentine inkjet printed interconnects on two different substrates were fabricated and electromechanically characterized. A particular attention was given to the optimization of the process parameters; high quality can be achieved only printing slowly in vertical direction and optimizing the drop spacing to the specific pattern. The electromechanical results showed that the geometrical layout and printing direction strongly affect the printing quality and the electromechanical response; serpentine shapes should be preferred to straight interconnects as better gauge factors are obtained. [ABSTRACT FROM AUTHOR]