Search Results (92)

Additive manufacturing (AM) has expanded the design space of biomaterials for biomedical engineering, enabling patient-specific geometries, controlled porosity, multi-material constructs and cell-compatible fabrication. However, clinical translation remains constrained by a mismatch between fabrication capability and biological, mechanical and regulatory performance. Unlike reviews focused on individual material families, isolated AM routes or specific applications, this review interprets AM of biomaterials as an integrated biomaterial–process–structure–property–translation ecosystem. It examines how material chemistry, feedstock state, printing route, architecture, post-processing and biological response jointly determine the reliability of acellular and cellular constructs, with particular emphasis on clinically relevant performance, reproducibility and long-term safety. Metallic, ceramic, polymeric, hydrogel-based and composite biomaterials are analysed alongside binder jetting (BJ), directed energy deposition (DED), material extrusion (ME) and jetting (MJ), powder bed fusion (PBF), VAT photopolymerisation and bioprinting. The review identifies recurring challenges across routes, including restricted material–process compatibility, limited prediction of process–structure–property relationships, post-processing-induced changes in biological performance, insufficient standardisation of printability and biofunctionality metrics, incomplete validation of cell-laden and vascularised constructs and weak transfer of laboratory protocols to clinically robust workflows. The main conclusion is that progress will depend less on expanding printable geometries alone and more on integrated optimisation of materials, processing windows, structural fidelity, biological validation, quality assurance and translational readiness. This ecosystem-level perspective provides a framework for evaluating limitations and defining future priorities in AM-based biomaterials for regenerative medicine, implants and precision biomedical engineering. Full article

This article reports on the synthesis and characterization of the properties of ceramic powders and aerogels of rare earths using the Sc₂O₃:Eu₂O₃ system synthesized through the sol–gel method, as well as on the toxicological effects of the cytokinesis-block micronucleus cytome assay (CBMC). A sol–gel variant using epoxide-assisted gelling and supercritical CO₂ drying was employed to produce the aerogels. In vitro CBMCs were employed to assess the genotoxic and cytotoxic effects of the materials’ dosages and inherent properties. The morphology of the powders and aerogels consisted of agglomerates of irregularly shaped particles. At the same time, structural analysis revealed crystal sizes of 16 and 10 nm, respectively, for the ceramic powders and aerogels, in which microplastic deformations were observed. The cubic crystalline structure of the Sc₂O₃:Eu₂O₃ system remained unchanged. However, applying CBMC and observing the genotoxic and cytotoxic effects of the nanoparticles revealed that the main genotoxic xenobiotic agent was the aerogel. The primary mode of cellular death was necrosis, suggesting that reactive oxygen species might have been involved in the genotoxic and cytotoxic damage. Full article

The influence of different heat treatment processes on the microstructure and mechanical properties of 18Ni350 maraging steel manufactured by selective laser melting and the corrosion resistance of TiB₂ ceramic coatings Electro-Spark-Deposited on its surface when immersed in high-temperature molten aluminum have been investigated in the present study. The microstructures and mechanical properties of the differently heat-treated samples were analyzed using various precision instruments. The results reveal that the as-built sample exhibits a microstructure composed of cellular and columnar dendritic grains. After solution treatment, the microstructure fully transforms into lath-like martensite. After direct aging treatment, the cellular structures diminish, while precipitates at grain boundaries proliferate with increasing aging temperature. SAT- treatment achieves full microstructural homogenization, featuring fine-lath martensite and a small amount of randomly distributed austenite particles. DA- and SAT- significantly improve the strength, hardness and modulus of samples and were found to reduce the toughness and plasticity. After solution treatment at 800 °C for 1 h followed by aging treatment at 520 °C for 6 h (SAT 800-520), the specimen achieved an UTS of 2476 MPa while maintaining an EL of 4.6%. The TiB₂ coating and the Cr interlayer deposited via ESD form a continuous interfacial bond with the substrate, demonstrating favorable adhesion. After 4 h of static immersion in high-temperature molten aluminum, the coating remains intact without complete delamination, delivering effective protection to the substrate. Full article

Dental composite dust generated during finishing procedures or mastication may adversely affect gingival epithelia. However, the mechanistic distinction between particulate and chemical (eluate) exposures and their respective signaling consequences remains insufficiently defined. Dust particles and corresponding eluates from three restorative composites, Admira Fusion, Ceram.x Spectra ST, and Filtek Supreme XTE, were evaluated under standardized high-dose in vitro exposure conditions. Human gingival keratinocytes were assessed for proliferation, adhesion, differentiation, fibronectin (FN1) remodeling, and IL-8 secretion, alongside analysis of ERK, p38, and NF-κB signaling and phosphorylation of the stress-responsive regulator SIRT1 at Ser682 (SIRT1-S682). Particulate exposure elicited more pronounced impairment of cellular adhesion, proliferation, and differentiation than eluates. Dusts derived from Ceram.x Spectra ST and Filtek Supreme XTE suppressed ERK activity, reduced FN1 abundance, and decreased nuclear SIRT1-S682, consistent with a generalized stress response. In contrast, Admira Fusion dust preserved FN1, activated ERK signaling, reduced SIRT1-S682, and induced robust IL-8 secretion. Across all materials, particulate exposure reduced nuclear SIRT1-S682 without affecting total SIRT1 levels, indicating a shared permissive stress modification. Notably, only Admira Fusion coupled this permissive state with p38 activation and sustained NF-κB p65 Ser536 phosphorylation, resulting in transcriptionally active NF-κB and elevated IL-8 production, whereas Ceram.x Spectra ST and Filtek Supreme XTE failed to activate this ERK–FN1–p38–NF-κB axis, yielding either transcriptionally inactive NF-κB or no detectable enrichment. These findings support a material-associated in vitro response pattern in which a shared SIRT1-S682 reduction is accompanied by distinct ERK/FN1, p38, NF-κB, and IL-8 readouts. SIRT1-S682 reduction alone did not define the inflammatory phenotype, because it occurred across particulate exposures, whereas IL-8 secretion was observed only under conditions that also showed p38 activation and comparatively maintained NF-κB p65 Ser536 phosphorylation. This signature arises from the convergence of a permissive SIRT1-S682 background with ERK- and p38-dependent MAPK signaling to enable NF-κB-mediated IL-8 expression, highlighting that both composite composition and particulate properties critically determine inflammatory potential and underscoring the importance of incorporating particulate fractions into cytocompatibility testing strategies. Full article

Bone tissue plays a vital role in the human body and possesses intrinsic self-repair mechanisms; however, large defects or pathological fractures may exceed its natural healing capacity. Bone tissue engineering provides promising strategies to restore bone integrity through the use of scaffolds, growth factors, and stem cells. While calcium phosphate (CaP)-based ceramics, such as hydroxyapatite (HAp) and tricalcium phosphate (TCP), represent the current benchmark, their limitations, including slow degradation (HAp) and limited osteoinductivity (TCP), have driven the development of alternative biomaterials. In this context, magnesium phosphate (MgP)-based materials have gained increasing attention due to their tunable resorption rate, improved biodegradability, and ability to stimulate osteogenesis and angiogenesis through the release of magnesium (Mg²⁺) ions. This study reports on composite scaffolds based on electrospun poly(ε-caprolactone) (PCL) fibres coated with MgP layers doped with lithium (Li) and zinc (Zn), designed to mimic the nanofibrous architecture of the extracellular matrix. Lithium and zinc were selected due to their known ability to modulate cellular response, with lithium promoting osteogenic activity and zinc contributing to improved cell proliferation and antibacterial potential. The phosphate phases obtained by coprecipitation were deposited onto the PCL fibres using Matrix-Assisted Pulsed Laser Evaporation (MAPLE), enabling controlled surface functionalization. Following thermal treatment, the formation of the crystalline magnesium pyrophosphate (Mg₂P₂O₇) phase was confirmed by chemical and structural characterization. The combination of a slowly degrading PCL matrix, providing sustained structural support, and a bioactive MgP coating, enabling rapid and controlled ion release, results in improved scaffold performance in terms of biocompatibility, biodegradability, and bioactivity. While the slow degradation rate of PCL ensures mechanical stability over an extended period, the surface-deposited MgP phase allows immediate interaction with the biological environment, facilitating faster ion release and enhancing cell–material interactions. These findings highlight the potential of the developed composites as promising candidates for trabecular bone regeneration and as viable alternatives to conventional CaP-based scaffolds in regenerative medicine. Full article

In the biodegradable metal class, Mg-based alloys are considered the most promising candidates for temporary implant manufacture. However, their high corrosion rate in physiological media is considered a main drawback for clinical translation. Conversion coatings address the limitations of Mg-based alloys and provide a strategy to control corrosion and improve surface biocompatibility. In this review paper, a detailed analysis of various conversion coating techniques, including ceramic conversion coatings based on metals, polymeric conversion coatings, bioactive conversion coatings, and hybrid conversion coatings, is performed. Attention is devoted to the corrosion process and parameters, as well as to the biological response in relation to bioactivity or biocompatibility. The main angiogenic and osteogenic signaling pathways are described based on the analyzed conversion coatings, and the evolution of the cellular response is estimated. Although significant progress has been made in the field, there are still challenges associated with synchronizing Mg alloy degradation with new bone formation and with precisely guiding cell signaling responses to achieve a desired biological response. An overall conclusion of the paper consists of the fact that conversion coatings are an important topic, as they can enhance the surface of Mg-based alloys, making them prone to clinical translation. Full article

To address the limitations in the corrosion resistance of 316L stainless steel, ceramic reinforcements are increasingly utilized in additive manufacturing. However, their influence on corrosion behavior varies significantly. Via laser powder bed fusion (LPBF), 316L stainless steel composites reinforced with, respectively, 1 wt.% ceramic particles (TiC, SiC, SiO₂, WC, Y₂O₃) were fabricated, and the comparing microstructure and corrosion performance was investigated in this work. The results indicated that ceramic particle addition increased porosity (0.24% to 1.40%) due to the thermal expansion coefficient mismatch between particles and matrix and defects from incompletely melted particles. Microstructural analysis revealed that LPBF-processed 316L exhibited cellular sub-grain boundaries with distinct melt pool boundaries. Ceramic particle addition refined sub-grain boundaries to varying degrees across composites, accompanied by increased sub-grain boundary density. Interfacial reactions and thermal stresses induced crack formation in SiC/316L and SiO₂/316L composites. Electrochemical testing demonstrated that Y₂O₃/316L exhibited the highest corrosion resistance, followed by TiC/316L and WC/316L. The corrosion resistance of the as-built L-BPF 316L matrix was inferior to that of these three composites. Conversely, SiC/316L and SiO₂/316L exhibited the poorest corrosion resistance. The optimized corrosion resistance of Y₂O₃/316L is hypothesized to result from pronounced grain refinement and the highest sub-grain boundary density, which provided abundant nucleation sites for passive film formation. Conversely, SiC/316L and SiO₂/316L showed lower corrosion resistance than the as-built L-BPF 316L matrix due to elevated defect density. Corrosion morphology analysis indicated preferential corrosion propagation along melt pool boundaries in 316L, TiC/316L, WC/316L, and Y₂O₃/316L. In contrast, pores and microcracks in SiC/316L and SiO₂/316L accelerated pit nucleation, indicating failure dominated by localized corrosion mechanisms. Full article

Modeling elementary diffusion processes in nanostructured materials is essential for developing platforms capable of interacting with high-speed physical signals. In this work, the photothermal response of a nano-hydroxyapatite/carbon nanotube (nHAp/CNT) composite was experimentally characterized and modeled through a cellular automaton (CA) framework designed to capture the thermal propagation of the hybrid system. Synthesizing nHAp/CNT composites enables the combination of the biocompatible and piezoelectric nature of nHAp with the enhanced photothermal response introduced by CNTs. UV–Vis reflectance measurements confirmed that CNT incorporation increases the optical absorption of the ceramic matrix, resulting in more efficient photothermal conversion. The composite was irradiated with a nanosecond pulsed laser, and the resulting thermal transients were compared with CA simulations based on a D2Q9 lattice configuration. The model accurately reproduces experiments, achieving R² > 0.991 and NRMSE below 2.4% for all tested laser powers. This strong correspondence validates the CA approach for predicting spatiotemporal heat diffusion in heterogeneous nanostructured composites. Furthermore, the model revealed a sensitive thermal coupling when two heat sources were considered, indicating synergistic enhancement of local temperature fields. These findings demonstrate both the effective integration of CNTs within the nHAp matrix and the capability of CA-based modeling to describe their photothermal behavior. Overall, this study establishes a computational–experimental basis for designing controlled thermal-wave propagation and guiding future multi-frequency or multi-source photothermal mixing experiments. Full article

Zirconia is widely used for customized implant abutments owing to its esthetics, strength, and biocompatibility; however, the optimal surface modification for soft-tissue sealing and bone metabolic remains uncertain. This study evaluated how glass–ceramic spray deposition (GCSD), with or without handheld nonthermal plasma (HNP), alters zirconia surface physiochemistry and cellular responses. Field-emission scanning electron microscopy/energy-dispersive X-ray spectroscopy, surface roughness (Ra), wettability, and surface free energy (SFE) were measured. Human osteoblast-like cells (MG-63) and human gingival fibroblasts (HGF-1) were used to assess attachment and spreading, metabolic activity, cytotoxicity, and inflammatory response (tumor necrosis factor-α, TNF-α) (α = 0.05). GCSD produced an interlaced rod- and needle-like glass–ceramic layer, significantly increasing Ra and hydrophilicity. HNP further reduced surface contaminants, increased SFE, and enhanced wettability. The combination of GCSD and HNP yielded the greatest attachment and spreading for both cell types, without increases in cytotoxicity or TNF-α. GCSD with HNP creates a hydrophilic, micro-textured, chemically activated zirconia surface that maintains biocompatibility while promoting early attachment and bone metabolic activity, supporting its application for zirconia implant abutments. Full article

In recent years, apatite-based materials have garnered significant interest, particularly for applications in tissue engineering. Apatite is most commonly employed as a coating for metallic implants, as a component in composite materials, and as scaffolds for bone and dental tissue regeneration. Among its various forms, hydroxyapatite (HAP) is the most widely used, owing to its natural occurrence in human and animal hard tissues. An emerging area of research involves the use of fluoride-substituted apatite, particularly fluorapatite (FAP), which can serve as a direct fluoride source at the implant site, potentially offering several biological and therapeutic advantages. However, substituting HAP with FAP may lead to unforeseen changes in material behavior due to the differing physicochemical properties of these two calcium phosphate phases. This study investigates the effects of replacing hydroxyapatite with fluorapatite in ceramic–polymer composite materials incorporating β-1,3-glucan as a bioactive polymeric binder. The β-1,3-glucan polysaccharide was selected for its proven biocompatibility, biodegradability, and ability to form stable hydrogels that promote cellular interactions. Nitrogen adsorption analysis revealed that FAP/glucan composites had a significantly lower specific surface area (0.5 m²/g) and total pore volume (0.002 cm³/g) compared to HAP/glucan composites (14.15 m²/g and 0.03 cm³/g, respectively), indicating enhanced ceramic–polymer interactions in fluoride-containing systems. Optical profilometry measurements showed statistically significant differences in profile parameters (e.g., Rp: 134 μm for HAP/glucan vs. 352 μm for FAP/glucan), although average roughness (Ra) remained similar (34.1 vs. 27.6 μm, respectively). Microscopic evaluation showed that FAP/glucan composites had smaller particle sizes (1 μm) than their HAP counterparts (2 μm), despite larger primary crystal sizes in FAP, as confirmed by TEM. XRD analysis indicated structural differences between the apatites, with FAP exhibiting a reduced unit cell volume (524.6 ų) compared to HAP (528.2 ų), due to substitution of hydroxyl groups with fluoride ions. Spectroscopic analyses (FTIR, Raman, ³¹P NMR) confirmed chemical shifts associated with fluorine incorporation and revealed distinct ceramic–polymer interfacial behaviors, including an upfield shift of PO₄³⁻ bands (964 cm⁻¹ in FAP vs. 961 cm⁻¹ in HAP) and OH vibration shifts (3537 cm⁻¹ in FAP vs. 3573 cm⁻¹ in HAP). The glucan polymer showed different hydrogen bonding patterns when combined with FAP versus HAP, as evidenced by shifts in polymer-specific bands at 888 cm⁻¹ and 1157 cm⁻¹, demonstrating that fluoride substitution significantly influences ceramic–polymer interactions in these bioactive composite systems. Full article

The development of bioactive glasses (BGs) and ceramics, such as β-Tricalcium phosphate (β-TCP), Hydroxyapatite (HAp), and apatite-wollastonite (A-W), has revolutionized regenerative medicine (RM), offering innovative solutions for bone and tissue repair, due to the ability of these materials to bond with living bone tissue. Despite significant advancements, evaluating the bioactivity and biological responsiveness of these biomaterials remains a critical challenge. This review provides a comprehensive synthesis of the available methodologies, critically analyzing their advantages, disadvantages, and the possible gap between in vitro and in vivo assessments, including false positives and false negatives. Classical immersion tests techniques for bioactivity evaluation in simulated physiological solutions, such as simulated body fluid (SBF), Tris-buffer (TRIS), or phosphate-buffered saline (PBS) solutions, are discussed, along with the more innovative Simulated Wound Fluid (SWF). Additionally, traditional standardized methods, such as MTT, BrdU, EdU, and XTT, as well as emerging methods like qPCR and immunocytochemistry, used to study cellular behavior, proliferation, adhesion, and differentiation, are compared. Staining assays, including crystal violet, neutral red, and alizarin red, have also been investigated for their effectiveness in evaluating cellular adhesion and quantification. Notably, while all techniques have shown promise in studies involving BGs and ceramics, a multi-parametric approach remains the most reliable strategy for assessing bioactivity and biological responsiveness, highlighting the need for comprehensive studies to validate the results. Finally, the choice between static and dynamic approaches represents a further critical issue, as it significantly affects assay outcomes. Full article

Bone tissue engineering has gained attention recently as a method for regenerating bone critical-size defects. This work aims to synthesize a hydrogel based on gelatin, di-amine polyethylene glycol, Polyethylene Glycol-Polypropylene Glycol-Polyethylene glycol, using genipin as a cross-linker and adding hydroxyapatite as a ceramic insert that can be used as a cellular scaffold in bone tissue engineering. Characterization was performed using Fourier transform infrared spectroscopy, identifying the leading absorption bands to verify that the hydrogels cross-linked correctly. The hydrogels with elastic modules and resistances that best adapted to the values reported for the mandibular trabecular bone were identified through mechanical tests. Using scanning electron microscopy, the presence of hydroxyapatite in the hydrogels was verified. The hydrogels with the best results were selected to carry out the biological assays. The cell viability assay verified that the osteoblastic cells proliferated better in the hydroxyapatite scaffolds, and the composite hydrogel induced osteoblast differentiation from undifferentiated mesenchymal stem cells. Hydrogels loaded with hydroxyapatite proved to be a promising biomaterial with potential application in bone regeneration. Full article

Solar fuels production requires developing redox active materials with porous structures able to withstand thermochemical cycles with enhanced thermal stability under concentrated solar irradiation conditions. The mechanical performance of 3D-printed, macroporous black zirconia gyroid structures, coated with redox-active ceria, was assessed for their suitability in solar thermochemical cycles for CO₂ and H₂O splitting. Experiments were conducted using a 1.5 kW solar furnace to supply the high-temperature concentrated heat to a windowed reaction chamber to carry out thermal redox cycling under realistic on-sun conditions. The ceria coating on ceramic structures improved the thermal stability and redox efficiency while minimizing the quantity of the redox material involved. Crushing strength measurements showed that samples not directly exposed to the concentrated solar flux retained their mechanical performance after thermal cycling (~10 MPa), while those near the concentrated solar beam focus exhibited significant degradation due to thermal stresses and the formation of Ce_xZr_1−xO₂ solid solutions (~1.5 MPa). A Weibull modulus of 8.5 was estimated, marking the first report of such a parameter for fused filament fabrication (FFF)-manufactured black zirconia with gyroid architecture. Failure occurred via a damage accumulation mechanism at both micro- and macro-scales. These findings support the viability of ceria-coated cellular ceramics for scalable solar fuel production and highlight the need for optimized reactor designs. Full article

Effective bone tissue regeneration remains pivotal in implant dentistry, particularly for edentulous patients with compromised alveolar bone due to atrophy and sinus pneumatization. Biomaterials are essential for promoting regenerative processes by supporting cellular recruitment, vascularization, and osteogenesis. This study presents the development and characterization of a novel lithography-printed ceramic β-TCP scaffold, with a macro/micro-porous lattice, engineered to optimize osteoconduction and mechanical stability. Morphological, structural, and biomechanical assessments confirmed a reproducible microarchitecture with suitable porosity and load-bearing capacity. The scaffold was also employed for maxillary sinus augmentation, with postoperative evaluation using micro computed tomography, synchrotron imaging, histology, and Fourier Transform Infrared Imaging analysis, demonstrating active bone regeneration, scaffold resorption, and formation of mineralized tissue. Advanced imaging supported by deep learning tools revealed a well-organized osteocyte network and high-quality bone, underscoring the scaffold’s biocompatibility and osteoconductive efficacy. These findings support the application of these 3D-printed β-TCP scaffolds in regenerative dental medicine, facilitating tissue regeneration in complex jawbone deficiencies. Full article

In this article, a novel method of achieving a single-layer, dual-band, dual-circularly polarized (CP) shared-aperture phased array antenna with wide beam scanning coverage is presented. The space antenna was designed to provide direct-to-cellular communications services at S-/C-bands with a frequency ratio of 1:1.8. Using novel ceramic substrates with high dielectric constants for antenna miniaturization, the optimum interelement spacing can be ensured in one single layer to meet the large-angle scanning demand. The CP characteristic of the phased array is improved by the sequential rotation technique. A prototype of phased array, which is composed of an 8 × 8 S-band Rx array and a 16 × 16 C-band Tx array, is fabricated to verify this design. The measured results show that the shared-aperture phased array can provide ±50° beam scanning coverage at both the S- and C-bands simultaneously to meet the direct-to-cellular communication demand in low earth orbit (LEO) satellites. Full article