Search Results (1,080)

Three-dimensional (3D) bioreactor systems are essential for vascular tissue engineering as they provide controlled environments that better mimic physiological conditions compared to static culture systems. In this study, an IoT-enabled modular rotating 3D bioreactor platform was designed, fabricated using Fused Deposition Modeling (FDM), and biologically validated. The system integrates a Wi-Fi-supported ESP8266 controller and a touchscreen human–machine interface (HMI), enabling real-time monitoring and remote operation. Agarose-chitosan-based tubular hydrogel constructs were seeded with human aortic smooth muscle cells (HASMCs) and cultured under dynamic conditions for 14 days. Biocompatibility was assessed using a lactate dehydrogenase (LDH) assay, while cellular distribution and mitochondrial activity were evaluated by confocal microscopy using DAPI and MitoTracker staining. Fluorescence intensity was further quantified using ImageJ, and 3D surface plots were generated to visualize spatial signal distribution. The results demonstrated sustained cell viability with decreasing cytotoxicity over time. Confocal analysis confirmed a homogeneous distribution of cells within the hydrogel matrix, and quantitative fluorescence analysis showed significantly higher MitoTracker intensity compared to DAPI, indicating increased metabolic activity under dynamic conditions. These findings suggest that the developed bioreactor provides a stable, controllable, and effective platform for vascular tissue engineering applications. Full article

Bone grafting remains limited, and the strategies to design even more structurally complex scaffolds—able to reproduce the hierarchical architecture of bone extracellular matrix—are rapidly growing. In this study, we report the fabrication of a hierarchically structured scaffold produced by layering poly(ε-caprolactone)/gelatin (PCL/Gt) or poly(lactic acid)/gelatin (PLA/Gt) electrospun nanofibers via coaxial electrospinning onto 3D-printed poly(lactic acid) (PLA) scaffolds via fused deposition modeling (FDM). After the printing process, PLA disks (10 × 1 mm, 20% infill, ~80% porosity, pore size ~1.57 mm) were coated with core/shell (PCL/Gt, PLA/Gt) fibers to investigate the in vitro interfacial response of osteoblasts in comparison with monocomponent fibrous coatings (PCL, PLA, Gt). SEM and TEM confirmed that core/shell fibers exhibited bead-free morphologies, with a significant reduction in fiber diameter (≈287–316 nm) and higher interfibrillar porosity compared to monocomponent fibers. FTIR and thermogravimetric analyses indicated the presence of hydrogen bonding between the polyester and gelatin, and the absence of residual solvent after deposition. At the same time, water contact angle measurements confirmed an increase in hydrophilic properties from 80–86° to 120° ascribable to the presence of gelatin. Accordingly, in vitro response of human fetal osteoblasts (hFOB 1.19) exhibited an evident improvement in the case of Gt-based fibrous coatings (i.e., PCL/Gt and PLA/Gt) in terms of early adhesion (4–24 h) and metabolic activity from 3 to 21 days, cell spreading into star-shaped morphologies, formation of extracellular matrix, and mineral phase deposition. In more detail, a remarkable increase in alkaline phosphatase activity was observed in Gt-based coaxial coatings from day 7 onward, with the highest values recorded for PLA/Gt. Overall, we demonstrated that the Gt-based coaxial fibrous coating provided a mix of topological and biochemical cues that synergistically promoted key osteoblast activities at the interface, supporting the regeneration of new bone tissue in highly tailored 3D-printed scaffolds, thus suggesting a promising strategy for personalized regenerative medicine. Full article

Extending the service life of structural components through sustainable replacement is a key strategy for reducing material consumption and environmental impact in the cycling industry. This study evaluates the potential substitution of bicycle frame components, combining fused deposition modeling (FDM) with externally applied fiber tape reinforcement. Preliminary experimental validation was conducted on coupon specimens to assess the mechanical and environmental viability of the proposed material system. Two thermoplastic substrates, a bio-based green co-polyester (GreenTEC PRO, GT) and polycarbonate (PC), were printed at three orientations and reinforced with unidirectional carbon fiber (CF) or flax fiber (Flax) tapes. The results show that fiber position was the dominant factor governing both ultimate flexural strength (UFS) and elastic modulus (EF), accounting for over 74% and 81% of total variability, respectively. Carbon fiber reinforcement increased mean UFS from 60.6 MPa to 142.9 MPa, with peak values of 236.4 MPa, while flax fiber provided a statistically significant intermediate reinforcement, reaching up to 108.9 MPa. The bio-based GT substrate performed comparably to PC across all configurations, demonstrating that sustainability goals need not compromise structural performance. Bilateral fiber placement and 90° printing orientation consistently yielded the best mechanical response. These findings support the hybrid FDM/prepreg approach as a viable, tooling-free, and environmentally conscious strategy for the replacement of bicycle frame components. Full article

Bone tissue engineering requires biomimetic materials; however, pure polylactic acid (PLA) exhibits limited osteoinductivity and produces acidic byproducts upon degradation. To address these limitations, this study fabricated PLA scaffolds using fused-deposition modeling (FDM) with four distinct lattice structures (rectangular, triangular, gyroid, and 3D honeycomb) and incorporated hydroxyapatite (HA) at 0, 10, 20, and 30 wt% via injection molding. Mechanical properties were evaluated via compression, three-point bending, and tensile testing. The results revealed that increasing HA content significantly reduced structural strength and increased brittleness across all test modes. Specifically, specimens with 30 wt% HA exhibited a 70.8% reduction in bending strength relative to pure PLA (from 58.60 MPa to 17.07 MPa), while tensile strength decreased by 46.1% at just 10 wt% HA (from 37.54 MPa to 20.23 MPa). Although the triangular lattice achieved the highest absolute compressive load, the rectangular lattice provided a superior load-to-weight ratio and greater plastic deformation capacity before fracture. Consequently, these findings indicate that the rectangular pattern at 70% infill density combined with HA addition limited to ≤10 wt% represents the most mechanically balanced design for bone defect repair applications. Based on the mechanical characterization performed in this study, and drawing on published evidence regarding the biological properties of PLA/HA composites, these scaffolds represent a mechanically promising candidate for further evaluation in bone tissue regeneration. Biological validation through in vitro and in vivo studies is required before clinical relevance can be established. Full article

Background/Objectives: An ideal bone scaffold should promote bone cell growth and functional vascularization, hence the importance of imbuing biomaterials with pro-angiogenic cues. In this work, silica-based bioactive glasses, either pristine (SBA3) or doped with copper (SBA3_Cu), were embedded in poly(ε-caprolactone) (PCL), which was also used as a control. Methods: In vitro co-cultures of adipose-derived mesenchymal stem/stromal cells (ASCs) and human microvascular endothelial cells (HMEC-1s) were kept in α-MEM, MCDB131, and EndoGRO media to test the biomaterials. The co-cultures were visualized by immunofluorescence and SEM, while flow cytometry was performed to characterize cellular immunophenotype. The angiogenic potential was evaluated using conditioned media of co-cultures to perform a tubulogenesis assay and VEGF-A quantification. Results: Immunophenotypic analysis showed a significant decrease in the endothelial CD31+ cellular subset, whereas the OB-like cellular subset expressing CD105, CD73, CD90, and ALP increased in all culture media over time. In α-MEM, HMEC-1s were unable to form a capillary network independent of the substrates. A more organized network was visible when co-cultures were plated on PCL, in MCDB131 and EndoGRO, or if they were kept in EndoGRO on PCL/SBA3_Cu. The VEGF-A concentrations were similar in the conditioned media from co-cultures grown on PCL/SBA_Cu, in EndoGRO, and on PCL and PCL/SBA3, in MCDB131. Conclusions: The presence of copper did not promote the angiogenic potential of HMEC-1, likely due to the low concentration of released copper ions and the predominant osteoinductive effect of the other ions released by the bioglass. A re-evaluation of formulation and structure of bioglass scaffold could enhance the angiogenic potential. Full article

The use of parts made of polymeric materials has occasionally highlighted the need for them to possess the best possible mechanical properties. One of the currently widely used processes for manufacturing parts from polymeric materials is fused deposition modeling. This process allows for variations in the magnitudes defining the mechanical properties of polymeric materials to be obtained through an appropriate selection of the process input factor values. The analysis of the process has highlighted the primary factors capable of affecting the values of parameters corresponding to the mechanical properties of polymeric materials. The opinions formulated by various researchers regarding the influence of fused deposition modeling application conditions on some of the mechanical properties of polymeric materials have been synthetically and systematically presented. In terms of mechanical properties, tensile strength, compression strength, elongation at break, flexural strength, torsional strength, impact strength, fatigue resistance, and hardness were taken into consideration. Some modeling and optimization solutions for the influence exerted by the 3D printing process input factors on the values of the parameters defining the mechanical properties of polymeric materials in parts manufactured via the FDM process were also highlighted. Full article

To address issues such as thermal stress concentration in metal bone implants produced via high-energy beam direct additive manufacturing, a method was proposed to fabricate porous titanium scaffolds. This approach combined Fused Deposition Modeling (FDM) with a debinding–sintering process. Ti/ABS composite filaments with titanium volume fractions of 35%, 40%, and 45% were successfully developed via a single-screw extrusion process. Their feasibility in the FDM process was subsequently verified. The effects of different processing parameters on the forming quality and dimensional accuracy of the green bodies were investigated. After debinding and sintering the composite scaffolds prepared with optimized parameters, structurally intact porous titanium scaffolds were obtained. Microscopic characterization shows that the scaffold surface consists primarily of titanium, and the pore structure remains intact. Furthermore, compression tests were performed on three types of porous titanium scaffolds with different porosities. The results indicate that the combination of ABS/titanium alloy composite filaments, FDM technology, and debinding–sintering post-processing enables the high-quality and efficient production of porous titanium scaffolds. The elastic modulus of the resulting scaffolds ranges from 1.2 to 1.6 GPa, and the compressive strength is between 25.7 and 68.3 MPa. The elastic modulus matches that of human cancellous bone. Meanwhile, the compressive strength is significantly higher than that of cancellous bone and falls between the values for cancellous and cortical bone. These mechanical properties meet the requirements for human bone, providing a new approach for the manufacture of orthopedic implants. Full article

Sustainability is an increasingly important objective in design and engineering, yet the environmental implications of advanced computational design methods remain insufficiently quantified. This study examines the contribution of topology optimization to sustainable product development when applied exclusively to a product’s internal structure, while preserving external geometry, mechanical performance, and design intent. The furniture sector was selected as a representative case due to its significant environmental footprint and the strong role of aesthetic requirements within the design methodology. A gate-to-gate Life Cycle Assessment was performed to compare a conventionally designed stool with an internally optimized counterpart, both developed under the same design constraints and manufactured via Fused Deposition Modeling using Carbon Fiber-reinforced PETG (CF-PETG). The results indicate that computational strategies can reduce material waste by 57.8% to 90% compared to traditional subtractive methods. However, these benefits may be partially offset by increased energy demand during additive manufacturing due to geometric complexity. An additional comparative assessment involving generative design demonstrates that alternative computational strategies can achieve more balanced trade-offs between material efficiency and manufacturing energy, supporting sustainability while respecting design methodology constraints. Full article

Bone plates are widely used in orthopaedic surgery to stabilise fractured bones and support healing following traumatic injuries or osteotomies. However, conventional metallic bone plates suffer from stress shielding and stiffness mismatch with bone, which can hinder optimal healing. Additive manufacturing enables the incorporation of novel metamaterial architectures into polymer-based implants to enhance mechanical properties. The fatigue behaviour of these implants during the healing period is critical to ensuring their structural integrity and long-term performance. In this study, the compressive fatigue performance of fused deposition modelling (FDM)-printed carbon fibre-reinforced polylactic acid (CF-PLA) bone plates were investigated. Four metamaterial structures—tetrachiral, re-entrant, rotating square, and hexagonal—were evaluated under strain-controlled cyclic loading at 20%, 40%, 60%, and 80% of their respective yield strains. The results showed a strong dependence of fatigue behaviour on lattice geometry. Among the tested configurations, the re-entrant structured bone plate exhibited the best overall fatigue performance, sustaining up to 100,000 cycles at moderate strain levels and showing delayed stiffness degradation under high strain conditions. In contrast, rotating square and hexagonal structures showed early stiffness loss and failure at higher strain levels. These findings highlight the importance of lattice design in fatigue performance, although FDM-induced printing defects significantly influence overall fatigue behaviour. Full article

The expansion of fused deposition modeling (FDM) usage for manufacturing parts through 3D printing has contributed to an intensification of researchers’ concerns regarding the sustainability of the mentioned process. In this regard, the aspects considered essential for defining the FDM process were first highlighted. For a rigorous approach to the research results achieved so far in the field of FDM process sustainability, a systemic analysis was carried out, taking into consideration the sustainability of the FDM process as a system, and identifying the input factors and output parameters of such a system. The evolution of knowledge regarding the approach to sustainability aspects of the FDM process has allowed for a highlighting of the main research directions addressed up to now in a direction. The main solutions proposed by various researchers for improving the sustainability of the FDM process were succinctly presented. Highlighting the results of research on the influence exerted by different input factors on the values of output parameters specific to FDM process sustainability was considered to be of interest. Various proposed solutions for modeling and optimizing the output parameters usable for evaluating the sustainability of the FDM process were investigated. A brief presentation of the evolution trends in research regarding FDM process sustainability was made. Full article

Background: Fused deposition modeling (FDM) is one of the most well-known and often published methods for 3D-printed drug delivery systems. In early scientific reports, the active pharmaceutical ingredients were added by soaking, but later, a new milestone was established, after researchers started to manufacture their own filaments by hot-melt extrusion (HME). The number of publications covering this method has multiplied in the last decade, a wide range of natural and synthetic polymers have been tested with versatile active pharmaceutical ingredient components, and various printing parameters and their effects have been investigated. Objectives: In this review, we aim to synthesize how the available quality by design approaches and the scientific results established so far can facilitate the creation of a guideline for appropriate quality production of HME-FDM 3D-printed pharmaceuticals. Methods: Based on PRISMA 2020 guidelines, a systematic search of relevant publications from 2015 to 2025 was carried out using the PubMed database. Twenty-six articles were included, based on number of monitored parameters and methodological description. Reporting of important quality processes and material parameters was assessed. Results: HME, the FDM, and analytical testing experiences were compared and collected into three tables from the selected publications. In two different sections, the pharmacopeial dosage-form tests and the involvement of process analytical technologies (PAT) were also analyzed. We found that reporting of influential parameters is heterogenous, and lack of robust reporting schemes limits the development of QbD approaches. Conclusions: Regarding the data, trends were synthetized, and a guideline was created which is limited by inconsistent parameter reporting. Full article

To monitor online the operational condition and quality of a desktop fused deposition modeling (FDM) printer, the dynamics of vibro-acoustics must be accurately understood. In this paper, an electromechanical coupling (EMT) framework is established to relate the dynamics of stepper actuation, the transmission chain, and machine motion, deriving a steady-state frequency–velocity mapping for steady or near steady printing segments. The mapping is evaluated by numerical calculation to obtain a theoretical drive frequency for different toolpath directions and commanded printing velocities. Validation is performed on the experiment platform I. Drive-side vibration is measured by an accelerometer mounted on the x-axis beam near the motor end. An acoustic channel is recorded as an auxiliary qualitative cross-check rather than for quantitative error evaluation. For steady printing segments, the dominant frequency in drive-side vibration is compared with the theoretical drive frequency. In the tested steady segments and toolpath directions, the relative error remained below 3%. In a further case study, the G-code is modified to introduce two constant printing velocity segments (40 mm/s and 80 mm/s) within the same continuous record, enabling a direct comparison of dominant frequencies between two steady segments. The results show that, under open-loop stepper drive and within the steady/near steady scope adopted here, a drive-related dominant frequency can be observed stably in the x-axis beam vibration response and matches the theoretical drive frequency. When the commanded constant printing velocity is doubled, the dominant frequency in drive-side vibration in the corresponding steady segment changes by approximately a proportional factor. This study provides a verifiable drive referenced frequency–velocity mapping for steady segments under the tested configuration and a traceable frequency reference for steady segment comparisons within the same print record in subsequent case studies. Full article

The widespread adoption of additive manufacturing, particularly selective laser sintering (SLS), has raised concerns about the disposal of unused thermoplastic powder residues, such as polyamide 12 (PA12). The high cost of PA12 and its degradation during the SLS process highlight the need for sustainable reuse strategies. This study evaluates the feasibility of reprocessing non-sintered PA12 powder without the addition of virgin material through fused deposition modeling (FDM) and injection molding (IM). Thermal analysis showed that the material retains processing temperatures comparable to virgin PA12. However, a significant reduction in melt flow index (≈61%) was observed, reflecting reduced processability and suggesting molecular-level changes affecting chain mobility. Injection molding demonstrated consistent mechanical behavior and good ductility, confirming its suitability for processing recycled PA12. In contrast, FDM processing resulted in higher variability and reduced ductility, mainly due to limitations in interlayer bonding associated with the increased viscosity of the material. Overall, the results highlight injection molding as a robust route for the valorization of non-sintered PA12, while FDM remains a feasible but less reliable alternative requiring further optimization. Full article

Adhesion between fused deposition modelling (FDM) printed polymers and textile substrates is critical for durable printed-on-textile hybrids. Since no dedicated test standard exists for additively manufactured textile interfaces, many studies use T-peel methods adapted from adhesive-bond standards. However, printed-on-textile joints are often governed by polymer penetration into the fabric and mechanical interlocking, rather than by a discrete adhesive layer. This work evaluates a fixture-based perpendicular (normal-separation) tensile method, using a circular dolly printed directly onto a cotton plain-weave substrate and a fully 3D-printable, threaded, self-aligning clamping assembly. Three representative filaments, namely polyethylene terephthalate glycol-modified (PETG), polylactic acid (PLA), and thermoplastic polyurethane (TPU), were tested using both the proposed pull-off method and an ISO 11339-type T-peel benchmark, with n = 8 specimens per polymer. The perpendicular method produced complete datasets for all polymers and clearly differentiated adhesion performance (TPU > PLA > PETG). In contrast, for T-peel, the standard evaluation window (25–125 mm) was completed for all PETG specimens but only for a subset of PLA specimens and a single TPU specimen. In the remaining tests, premature substrate failure prevented completion of this window, so the results could not be evaluated. Microscopy confirmed distinct interlocking morphologies across polymers, supporting the observed differences in failure behavior between peel and normal separation. Overall, the results indicate that perpendicular dolly pull-off testing is a practical and reproducible alternative for quantifying adhesion across a wider range of printed-on-textile bonding conditions. Full article

This study investigates the influence of physiological body fluids on the mass stability and tribological performance of polylactic acid (PLA) samples produced by Fused Deposition Modeling (FDM) 3D printing. Body fluid exposure was simulated using Dulbecco’s Modified Eagle Medium (DMEM) under controlled conditions. Black PLA filament was printed with three infill densities (15%, 20%, and 90%) and immersed in DMEM for 7 days at 37 ± 1 °C. Mass measurements revealed that lower infill densities resulted in significantly higher mass loss, with the 15% infill samples exhibiting the greatest reduction (5.07%), while the 90% infill samples showed negligible change (0.17%). Tribological testing using a CSM nanotribometer under loads of 5 mN, 500 mN, and 1000 mN demonstrated that infill density critically affects friction and wear behavior. The 90% infill samples exhibited the lowest wear volumes and the most stable tribological response, while the 15% infill samples showed degradation-dominated contact behavior. Although the friction measurements for the 15% infill samples were consistent, their interpretation should be approached with caution due to pronounced surface deterioration and debris-mediated sliding. This behavior is attributed to structural weakening caused by immersion in DMEM, which promoted material degradation and influenced the tribological response. These findings confirm the critical role of structural density in wear resistance. To the best of our knowledge, this is the first study to systematically investigate the combined effect of hydrolytic degradation and tribological behavior of FDM-printed PLA as a function of infill density under simulated physiological conditions. These findings provide a scientific basis for optimizing infill density in the design of PLA-based surgical instrument guides, where both degradation resistance and tribological performance under body fluid exposure are essential. The findings should be interpreted within the limitations of the experimental design. Full article