This paper offers a review of present achievements in the field of processing of ceramic-based materials with complex geometry using the main additive manufacturing (AM) technologies. In AM, the geometrical design of a desired ceramic-based component is combined with the materials design. In this way, the fabrication times and the product costs of ceramic-based parts with required properties can be substantially reduced. However, dimensional accuracy and surface finish still remain crucial features in today's AM due to the layer-by-layer formation of the parts. In spite of the fact that significant progress has been made in the development of feedstock materials, the most difficult limitations for AM technologies are the restrictions set by material selection for each AM method and aspects considering the inner architectural design of the manufactured parts. Hence, any future progress in the field of AM should be based on the improvement of the existing technologies or, alternatively, the development of new approaches with an emphasis on parts allowing the near-net formation of ceramic structures, while optimizing the design of new materials and of the part architecture.

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A novel class of preceramic paper may serve as a preform to manufacture lightweight as well as multilayer ceramic products. In this article, we discuss the formation, microstructure, and properties of preceramic papers and their conversion into ceramic materials. Oxide as well nonoxide ceramics were processed into single‐sheet, corrugated structures, and multilayer ceramics. A high filler loading and uniform distribution of ceramic fillers involves control of colloidal surface interaction including electrostatic, electrosteric, and mechanical retention. Sintering of an oxide‐loaded preceramic paper in air results in highly porous products, with the porosity shape and distribution templated by the pulp fiber used in papermaking. In the case of carbide‐loaded paper, dense composite materials are obtained by reactive infiltration processing. Anisotropic properties of machine‐fabricated preceramic paper and bonding interfaces in multilayer stacks give rise to anisotropic mechanical properties of the resulting ceramic composites. Noncatastrophic failure was observed when tensile loading stress was applied parallel to the interfaces (in‐plane loading). Applying well‐established paper processing technologies, including laminated object manufacturing, ceramic structures of complex shape and size can easily be processed, offering a high potential for economical manufacturing.

Guided tissue regeneration (GTR) membranes have been used for the management of destructive forms of periodontal disease as a means of aiding regeneration of lost supporting tissues, including the alveolar bone, cementum, gingiva and periodontal ligaments (PDL). Currently available GTR membranes are either non-biodegradable, requiring a second surgery for removal, or biodegradable. The mechanical and biofunctional limitations of currently available membranes result in a limited and unpredictable treatment outcome in terms of periodontal tissue regeneration. In this study, porous membranes of chitosan (CH) were fabricated with or without hydroxyapatite (HA) using the simple technique of freeze gelation (FG) via two different solvents systems, acetic acid (ACa) or ascorbic acid (ASa). The aim was to prepare porous membranes to be used for GTR to improve periodontal regeneration. FG membranes were characterized for ultra-structural morphology, physiochemical properties, water uptake, degradation, mechanical properties, and biocompatibility with mature and progenitor osteogenic cells. Fourier transform infrared (FTIR) spectroscopy confirmed the presence of hydroxyapatite and its interaction with chitosan. μCT analysis showed membranes had 85-77% porosity. Mechanical properties and degradation rate were affected by solvent type and the presence of hydroxyapatite. Culture of human osteosarcoma cells (MG63) and human embryonic stem cell-derived mesenchymal progenitors (hES-MPs) showed that all membranes supported cell proliferation and long term matrix deposition was supported by HA incorporated membranes. These CH and HA composite membranes show their potential use for GTR applications in periodontal lesions and in addition FG membranes could be further tuned to achieve characteristics desirable of a GTR membrane for periodontal regeneration.

BackgroundRising criticism of currently available contrast agents for magnetic resonance imaging, either due to their side effects or limited possibilities in terms of functional imaging, evoked the need for safer and more versatile agents. We previously demonstrated the suitability of novel dextran-coated superparamagnetic iron oxide nanoparticles (SPIONDex) for biomedical applications in terms of safety and biocompatibility.MethodsIn the present study, we investigated the size-dependent cross-linking process of these particles as well as the size dependency of their imaging properties. For the latter purpose, we adopted a simple and easy-to-perform experiment to estimate the relaxivity of the particles. Furthermore, we performed an extensive analysis of the particles’ storage stability under different temperature conditions, showing their superb stability and the lack of any signs of agglomeration or sedimentation during a 12 week period.ResultsIndependent of their size, SPIONDex displayed no irritation potential in a chick chorioallantoic membrane assay. Cell uptake studies of ultra-small (30 nm) SPIONDex confirmed their internalization by macrophages, but not by non-phagocytic cells. Additionally, complement activation-related pseudoallergy (CARPA) experiments in pigs treated with ultra-small SPIONDex indicated the absence of hypersensitivity reactions.ConclusionThese results emphasize the exceptional safety of SPIONDex, setting them apart from the existing SPION-based contrast agents and making them a very promising candidate for further clinical development.