Search Results (2,124)

Patient-specific cutting guides are used for safe and accurate jaw resection during oral and maxillofacial surgery. This study investigated the effect of shavings from 3D-printed cutting guide materials during surgery on bone healing. The biocompatibility of commercially available biocompatible polymers including photopolymer resin (PP) and polyamide resin (PA) materials was assessed in the present study. The viability of mouse osteoblast-like MC3T3E-1 cells was evaluated upon coculture with the materials. Furthermore, the effects of PP and PA as additives on bone formation were investigated in a rat calvarial bone defect model. Both PP and PA were biocompatible and allowed cells to attach to them. However, both materials could be damaged when cutting devices were used, and their shavings impaired osteoblast proliferation and bone formation. Cutting guide materials are designed to be biocompatible when they are fabricated according to the manufacturer’s protocol. Nevertheless, the polymer shavings generated during jaw cutting might adversely affect bone healing. Full article

The study presented an analysis of the behaviour of cellular structures under bending, produced using the PolyJet Matrix (PJM) additive manufacturing method with photopolymer resin. Structures with regular cell geometry were designed to achieve a balance between stiffness, weight reduction, and energy absorption capacity. The aim of this study was to investigate the influence of unit-cell topology (quasi-similar, spiral, hexagonal honeycomb, and their core–skin hybrid combinations) on the flexural properties and deformation mechanisms of PolyJet-printed photopolymer beams under three-point bending. Additionally, all cellular configurations were fully infiltrated with a low-modulus platinum-cure silicone to evaluate the effect of complete polymer–elastomer interpenetration on load-bearing capacity, stiffness, ductility, and energy absorption. All tests were performed according to bending standard on specimens fabricated using a Stratasys Objet Connex350 printer with RGD720 photopolymer at 16 µm layer thickness. The results showed that the dominant failure mechanism was local buckling and gradual collapse of the cell walls. Among the silicone-filled cellular beams, the QS-Silicone configuration exhibited the best overall flexural performance, achieving a mean peak load of 37.7 ± 4.2 N, mid-span deflection at peak load of 11.4 ± 1.1 mm, and absorbed energy to peak load of 0.43 ± 0.06 J. This hybrid core–skin design (quasi-similar core + spiral skin) provided the optimum compromise between load-bearing capacity and deformation capacity within the infiltrated series. In contrast, the fully dense solid reference reached a significantly higher peak load of 136.6 ± 10.2 N, but failed in a brittle manner at only ~3 mm deflection, characteristic of UV-cured rigid photopolymers. All open-cell silicone-filled lattices displayed pseudo-ductile behaviour with extended post-peak softening, enabled by large-scale elastic buckling and silicone deformation and progressive buckling of the thin photopolymer struts. The results provided a foundation for optimising the geometry and material composition of photopolymer–silicone hybrid structures for lightweight applications with controlled stiffness-to-weight ratios. Full article

This study examines the in-plane compression behavior of sandwich panels produced with additive manufacturing. This study focuses on two types of honeycomb unit cell topologies with larger dimensions: a hexagonal one and a re-entrant one. For each panel geometry, two material configurations were examined: Onyx (a nylon-based composite) and Onyx reinforced with 10% continuous carbon fibers (CCFs) by mass. The objective was to assess the influence of fiber reinforcement on the mechanical performance and deformation response of the panel structures. In-plane compression tests were conducted to determine the stiffness, strength, and failure modes of the specimens. Additionally, the digital image correlation (DIC) technique was used to capture full-field strain distributions and analyze local deformation mechanisms during loading. The results revealed distinct mechanical responses between the two geometries: the re-entrant structure exhibited auxetic behavior and enhanced energy absorption characteristics. Although reinforced honeycomb panels have an average load capacity that is 35% higher, they fail at a displacement that is approximately 55% smaller compared to unreinforced panels. Despite accounting for only 25% of the total number of layers and 10% of the panel’s mass, the reinforcement achieved superior strength. Re-entrant panel testing showed a 25% force increase in favor of the reinforced variant. They fail at a displacement that is 36.5% greater than that of reinforced honeycombs. This demonstrates a more compliant response while also maintaining 4.9% greater strength, indicating the superior behavior of auxetic reinforced sandwich panels. Introducing CCF reinforcement increased the load-bearing capacity and reduced localized strain concentrations without altering the overall deformation pattern. These findings suggest that enhancing materials can increase the strength and flexibility of 3D-printed re-entrant structures, providing valuable insights for lightweight design and optimized material use in structural applications. Full article

Silicon dioxide (SiO₂) nanoparticles approximately 5 nm in size have been obtained. A method has been developed for introducing SiO₂ nanoparticles into photolithographic resin at concentrations up to 0.1%. Composite resins can be used to manufacture parts with complex geometries with a maximum achievable resolution of 50 μm. Parts made from composite resin with SiO₂ nanoparticles polish well. After polishing, areas of approximately 100 μm² with height differences of less than 10 nm are revealed on the surface of the parts. A relatively uniform distribution of SiO₂ nanoparticles is observed within the parts, and no optical defects are detected. However, areas differing in the phase shift of electromagnetic radiation are observed within the parts. Importantly, the presence of nanoparticles in the resin during MSLA printing increases the degree of resin polymerization. SiO₂ nanoparticles have been shown to have prooxidant properties, leading to the formation of 8-oxoguanine in DNA and long-lived reactive protein species. Components made from photolithographic resins with SiO₂ nanoparticles have been shown to inhibit the growth and development of E. coli bacteria, with a significant loss of viability. Despite their antimicrobial properties, components made from photolithographic resins with SiO₂ nanoparticles do not affect the growth and development of mammalian cells. Full article

In this study, a battery case was developed using a 3D (three dimensional)-printed composite of hexagonal boron nitride (hBN) and polylactic acid (PLA) to enhance the thermal performance of lithium-ion battery (LiB) modules. A 10 wt.% amount of hBN was incorporated into the PLA matrix to improve the composite’s thermal conductivity while maintaining electrical insulation. A 3S2P (3 series and 2 parallel) battery configuration was initially evaluated based on the results of a baseline study for comparison and subsequently subjected to a newly developed test procedure to assess the thermal behavior of the designed case under identical environmental conditions. Initially, X-ray diffraction (XRD) and scanning electron microscopy (SEM) analyses were utilized for material characterization, and their results verified the successful integration of hBN by confirming its presence in the hBN-PLA composite. In thermal tests, experimental results revealed that the fabricated hBN-PLA composite battery case significantly enhanced heat conduction and reduced surface temperature gradients compared to the previous baseline study with no case. Specifically, the maximum cell temperature (T_max) decreased from 48.54 °C to 45.84 °C, and the temperature difference (ΔT) between the hottest and coldest cells was reduced from 4.65 °C to 3.75 °C, corresponding to an improvement of approximately 20%. A 3S2P LiB module was also tested under identical environmental conditions using a multi-cycle charge–discharge procedure designed to replicate real electric vehicle (EV) operation. Each cycle consisted of sequential low and high discharge zones with gradually increased current values from 2 A to 14 A followed by controlled charging and rest intervals. During the experimental procedure, the average ΔT between the cells was recorded as 2.38 °C, with a maximum value of 3.50 °C. These results collectively demonstrate that the 3D-printed hBN-PLA composite provides an effective and lightweight passive cooling solution for improving the thermal stability and safety of LiB modules in EV applications. Full article

The paper is concerned with experimental investigations and numerical simulations of airflow in a rigid model of human tracheal bifurcation during a respiratory cycle in the presence of cough. The main goal of the study is to calculate the velocity and tracheal wall shear stress (WSS) distributions under the time variation in the pressure difference. A sequence of inspiration-expiration of measured flow rates and pressure is used to calibrate the 3D unsteady numerical solutions for different imposed boundary conditions at the edges of the bifurcation. The experimental data are obtained using commercial medical devices: (i) a spirometer and (ii) a mechanical ventilator, respectively. CT images of the lung airways were used to reconstruct the tracheal test geometry by 3D printing techniques. Flow spectrum, vortical structures, and the wall stresses are analyzed for the computed cases. Four turbulence models (k − ɛ, k − ω SST, k − ɛ R, and LES) are compared, and all indicate an increase in peak WSS and vortex intensity during coughing versus normal expiration. The present work confirms the importance of CFD simulations to model and quantify airflow throughout the respiratory cycle. The paper proposes a method to calculate wall shear stress, one of the most relevant parameters for characterizing airway function and the mechanical response of tracheal endothelial cells. Full article

The rapid development of 3D bioprinting technology has not been critically evaluated for its potential clinical applications… The ability of 3D manufacturing to create organ-like structures obscures the fact that the formed grafts are not physiologically relevant. We hypothesize that researchers do not use techniques that allow for the evaluation of the micro-architectonics of formed implants and mainly focus on biocompatibility and commonly observed immunological responses. This study aims to investigate the morphological landscape of the basics of 3D bioprinting through a systematic review of the outcomes of the experimental implantation of bioprinted constructs. A systematic search was conducted in the PubMed database using the following query: (bioprinting OR printing OR bioprinted OR printed OR bioinks) AND (cell OR cells) AND (implantation OR implanted OR in vivo) AND (goat OR porcine OR pig OR swine OR dog OR rabbit OR sheep) NOT (human OR humans). This systematic review evaluated the preformed studies of the in vivo assessment the 3D-bioprinted constructs, and 41 articles meeting the inclusion criteria were selected. We concluded that 3D bioprinting has limited applications for forming living tissue for orthotopic implantation. Additionally, quantitative methods for evaluating the properties and morphological quality of implanted bioprinted constructs have not been developed for tissue engineering applications. Full article

Craniofacial bone defects of critical size, caused by trauma, tumors, infections, or congenital maldevelopment, represent a major challenge in plastic and reconstructive surgery. Autologous bone grafting is considered the gold standard, but limitations such as donor site morbidity and limited availability have prompted the development of artificial bone tissue engineering scaffolds. In recent years, bioactive scaffolds have been increasingly utilized in favor of inert biomaterials due to their immunomodulation and osteoinduction capabilities. This review methodically summarizes loading strategies for the functionalization of scaffolds with bioactive components, including cell regulatory factors, drugs, ions, stem cells, exosomes, and components derived from human tissues or cells to promote bone regeneration. The following mechanisms are involved: (1) the polarization of macrophages (M1-M2 transition), (2) the dynamic regulation of bone metabolism, and (3) the coupling of osteogenesis and angiogenesis. This review focuses on innovative delivery systems, such as 3D-printed scaffolds, nanocomposites and so on, that enable spatiotemporal control of bioactive cargo release. These address key challenges, such as infection resistance, vascularization, and mechanical stability in the process of bone regeneration. In addition, the article discusses emerging technologies, including stem cells and exosome-based acellular therapies, which demonstrate potential for personalized bone regeneration. This review integrates immunology, materials science, and clinical needs, providing a roadmap for the design of next-generation bone tissue engineering scaffolds to overcome critical-sized bone defects. Full article

Tissue engineering offers a promising solution by developing scaffolds that mimic the extracellular matrix and guide cellular growth and differentiation. Recent evidence suggests that scaffolds must provide not only biocompatibility and appropriate mechanical properties, but also the structural complexity and heterogeneity characteristic of natural tissues. Particle-based scaffolds represent an emerging paradigm in regenerative medicine, wherein micro- and nanoparticles serve as primary building blocks rather than minor additives. This approach offers exceptional control over scaffold properties through precise selection and combination of particles with varying composition, size, rigidity, and surface characteristics. The presented review examines the fundamental principles, fabrication methods, and properties of particle-based scaffolds. It discusses how interparticle connectivity is achieved through techniques such as selective laser sintering, colloidal gel formation, and chemical cross-linking, while scaffold architecture is controlled via molding, templating, cryogelation, electrospinning, and 3D printing. The resulting materials exhibit tunable mechanical properties ranging from soft injectable gels to rigid load-bearing structures, with highly interconnected porosity that is essential for cell infiltration and vascularization. Importantly, particle-based scaffolds enable sophisticated pharmacological functionality through controlled delivery of growth factors, drugs, and bioactive molecules, while their modular nature facilitates the creation of spatial gradients mimicking native tissue complexity. Overall, the versatility of particle-based approaches positions them as prospective tools for tissue engineering applications spanning bone, cartilage, and soft tissue regeneration, offering solutions that integrate structural support with biological instruction and therapeutic delivery on a single platform. Full article

Dye-sensitized solar cells (DSSCs) are considered a prospective alternative to silicon-based solar cells due to their lower production cost and simpler fabrication process than conventional solar cells. DSSCs’ adjustable optical properties enable them to function effectively under diverse illumination conditions, making them ideal for powering small electronic devices in indoor environments. In DSSCs, silver nanoparticles (AgNPs) are incorporated into titanium dioxide (TiO₂) photoanodes due to their localized surface plasmon resonance (LSPR) effect, which enhances scattering and absorbing incident light and creates a strong electromagnetic field near the surface. There are diverse manufacturing methods for DSSCs, while the screen printing method is preferred because the area of the TiO₂ film can be easily customized to effectively reduce human error and make the film highly stable. In this study, eight different stacked DSSC film structures were fabricated by adding AgNPs to TiO₂ films. The TiO₂ paste with a concentration of 3 mwt% (percentage by mass) of AgNPs performed best in this study. The photovoltaic performance was evaluated using power conversion efficiency (PCE), and the results showed that the AgNP-doped film on the surface of the fluorine-doped tin oxide (FTO) glass significantly improved the photovoltaic performance. The three layers of TiO₂ doped with AgNPs achieved the highest PCE. PCE was increased since the TiO₂ film containing AgNPs became thicker and closer to the FTO substrate. The PCE of DSSCs was compared using pure TiO₂ NPs and the AgNP-doped TiO₂ photoanode. The efficiency increased from 5.67% to a maximum of 6.13%. This enhanced efficiency, driven by LSPR and improved electron transport, confirms the viability of screen-printed, plasmon-enhanced photoanodes for high-efficiency DSSCs. Full article

Breast cancer remains the most prevalent malignancy among women worldwide, with hormone receptor-positive (HR+) tumors comprising approximately 70% of cases. Traditionally, HR+ breast cancer has been classified as immunologically “cold” due to its low PD-L1 expression, reduced tumor-infiltrating lymphocytes, and low tumor mutational burden, collectively limiting immunotherapy responsiveness. However, emerging evidence indicates significant molecular heterogeneity within HR+ tumors, characterized by specific genetic signatures and features of the tumor microenvironment (TME) that can be therapeutically reprogramed through chemotherapy-induced immunogenic cell death combined with immune checkpoint inhibition. Recent clinical trials demonstrate that biomarker-selected immune-enriched HR+ subsets, identified by MammaPrint Ultra-High 2 classification, homologous recombination deficiency, or elevated tumor-infiltrating lymphocytes, achieve notable pathological complete response rates with immune checkpoint inhibitor combinations. This review summarizes the dynamic interactions between genetic determinants and TME plasticity in HR+ breast cancer and critically assesses combination strategies across 31 neoadjuvant trials. We demonstrate that optimal efficacy requires biomarker-guided patient selection integrating genetic and TME features, precise sequencing, and a mechanistic understanding of drug-specific immunomodulatory effects. The integration of platform trial designs (I-SPY2, CheckMate-7FL) with composite biomarker algorithms represents a paradigm shift toward precision neoadjuvant immunotherapy, offering a conceptual framework for transforming outcomes in molecularly defined HR+ breast cancer subsets. Full article

Bioprinting of Advanced Therapy Medicinal Products offers promising new strategies for personalized medicine, but it requires comprehensive, non-destructive characterization and quality monitoring. To support patients with tailor-made constructs composed of hydrogels and cells derived from allogeneic donors or autologous samples, several challenges must be addressed—such as on-demand production, robust manufacturing, appropriate storage and logistics, and destruction-free quality control—before successful translation into clinical applications or pharmacy is possible. Although experience in cryo-preservation, blood banking, and organ donation helps to identify critical process parameters, detecting variations in manufacturing and ensuring product stability remain essential. Quality monitoring of 3D-printed objects before and after storage by magnetic resonance imaging (MRI) is complemented here by measurements of total mass and volume. These established methods provide rapid, non-destructive feedback and have well-characterized statistical limitations. Total mass can be assessed quickly; however, such integral measurements do not reveal information about internal structures. MRI, in contrast, offers detailed, spatially resolved insights. By combining these analytical modalities, we quantitatively analyzed the storage stability of 3D-printed hydrogels—without living cells in this study—in order to demonstrate and validate the analytical approach. We describe a workflow for measuring mass and geometry of 3D-printed hydrogel lattices before and after storage under varying process parameters. Critical quality attributes (cQAs), including overall and internal structural fidelity as well as mass conservation, were monitored. The presented workflow supports the development of cryopreservation protocols and has potential applications in biomaterial development for bioprinting and in quality assessment of tailor-made artificial tissues. Full article

This study investigates the mechanical behavior and energy absorption capacity of a novel metamortar composite, developed by embedding re-entrant auxetic cellular structures into a cementitious mortar matrix. Auxetic materials, which exhibit a negative Poisson’s ratio, offer distinct advantages in impact resistance and stress dissipation. Despite their promising properties, their integration into cement-based systems remains limited. In this work, auxetic cells were fabricated using different 3D printing filaments and combined with mortar to form hybrid composites. The specimens were subjected to quasi-static compression tests to evaluate their Young’s modulus, yield strength, and energy absorption capacity. Results indicate that the auxetic inclusions substantially improved the mechanical performance of the mortar, particularly in the case of PLA-based cells, which achieved the highest values across all tested parameters. The enhancements are attributed to the synergistic deformation mechanisms of the auxetic geometry and the surrounding matrix, promoting efficient load distribution and delayed crack propagation. These findings contribute to the advancement of cementitious metamaterials and establish a foundation for scaling toward metaconcrete systems with improved energy dissipation for use in protective, seismic, and infrastructure applications. Full article

Poly(amino acids) and gold nanoparticles are stable and biocompatible materials with distinguishing features which can be used to build nanocomposite electrochemical platforms for sensing applications. This paper presents the optimization of the building steps of these nanocomposite platforms using cyclic voltammetry. Screen-printed graphite electrodes were first modified by electropolymerizing various l-amino acids and then by electrodepositing gold nanoparticles. The electroactive surface area was calculated for all platforms, which were then applied in the electrochemical oxidation of 1-naphthol as a model analyte: oxidation peaks were observed in all cases, with the current peak height increasing with increasing analyte concentration, thus demonstrating the potential of nanocomposite platforms for developing electrochemical sensors and biosensors. Full article

This study addresses the challenges of osteochondral tissue engineering by developing a hybrid scaffold with intercalated layers of poly(ε-caprolactone) (PCL) in combination with different concentrations of nanosized synthetic smectic clay (Lap) and a hydrogel of chitosan, collagen and demineralized bone powder (DBP). The scaffold design specifically targets the critical junction between subchondral bone and calcified cartilage and utilizes the mechanical strength of PCL/Lap nanocomposites and the bioactivity of the chitosan/collagen/DBP hydrogel to support tissue regeneration. The PCL/Lap nanocomposite, characterized by increased hydrophilicity, improved swelling behavior, and enhanced stiffness, provides a robust scaffold, while the hydrogel layers improve bioactivity and fluid retention. Three-dimensional printing technology was used to fabricate multi-layer scaffold, ensuring interfacial cohesion between the layers. Rheological, morphological, chemical, and mechanical characterizations confirmed the successful integration of the materials and the mechanical suitability for the subchondral environment. Biocompatibility assays demonstrated the non-hemolytic nature of the scaffolds and a favorable trend in cell viability with increasing Lap content. This study presents a novel scaffold design that effectively combines mechanical stability and biological functionality. It fulfills the complex requirements of osteochondral repair and offers a promising platform for future tissue engineering strategies. Full article