Search Results (9,577)

The development of biocompatible hydrogels for 3D bioprinting is essential for creating functional tissue models and advancing preclinical drug testing. This study investigates the formulation, printability, mechanical properties, and biocompatibility of a novel Alg-Gel hydrogel blend (alginate and gelatin) for use in extrusion-based 3D bioprinting. A range of hydrogel compositions were evaluated for their rheological behavior, including shear-thinning properties, storage modulus, and compressive modulus, which are crucial for maintaining structural integrity during printing and supporting cell viability. The printability assessment of the 7% alginate–8% gelatin hydrogel demonstrated that the 27T tapered needle achieved the highest normalized Printability Index (POI_normalized = 1), offering the narrowest strand width (0.56 ± 0.02 mm) and the highest printing accuracy (97.2%) at the lowest printing pressure (30 psi). In contrast, the 30R needle, with the smallest inner diameter (0.152 mm) and highest printing pressure (80 psi), resulted in the widest strand width (0.70 ± 0.01 mm) and the lowest accuracy (88.8%), resulting in a POI_normalized of 0.274. The 30T and 27R needles demonstrated moderate performance, with POI_normalized values of 0.758 and 0.558, respectively. The optimized 7% alginate and 8% gelatin blend demonstrated favorable printability, mechanical strength, and cell compatibility with MDA-MB-213 breast cancer cells, exhibiting high cell proliferation rates and minimal cytotoxicity over a 2-week culture period. This formulation offers a balanced approach, providing sufficient viscosity for precision printing while minimizing shear stress to preserve cell health. This work lays the groundwork for future advancements in bioprinted cancer models, contributing to the development of more effective tools for drug screening and personalized medicine. Full article

This research focuses on the design of a three-finger adaptive gripper using additive manufacturing and electromechanical actuators, with the purpose of providing a low-cost, efficient, and reliable solution for easy integration with any robot arm for industrial and research purposes. During the development phase, 3D printing materials were employed in the gripper’s design, with Polylactic Acid (PLA) filament used for the rigid mechanical components and Thermoplastic Polyurethane (TPU) for the flexible membranes that distribute pressure to the resistive force sensors. Stress analysis and simulations were conducted to evaluate the performance of the components under load and to gradually refine the design of the adaptive gripper. It was ensured that the mechanism could integrate effectively with the robotic arm and be precisely controlled through a PID controller. Furthermore, the availability of spare parts in the local market was considered essential to guarantee easy and cost-effective maintenance. Tests were conducted on an actual robotic arm, and the designed gripper was able to effectively grasp objects such as a soda can and a pencil. The results demonstrated that the adaptive gripper successfully achieved various types of grasping, offering a scalable and economical solution that represents a significant contribution to the field of robotic manipulation in industrial applications. Full article

Background: This study evaluates the impact of three-dimensional (3D) printing-guided maxillectomy compared with conventional maxillectomy on surgical precision and oncological outcomes in patients with head and neck cancer. Materials and Methods: A retrospective analysis was conducted on 42 patients undergoing maxillectomy (16 in a 3D printing-guided group and 26 in a conventional group). Patient demographics, tumor characteristics, and outcomes were compared. Survival outcomes were analyzed using the Kaplan–Meier method. Results: The 3D printing group showed higher rates of negative resection margins (81.3% vs. 76.9%) compared with the conventional group and a trend toward improved 5-year local recurrence-free survival (87.5% vs. 58.7%, respectively) and overall survival (84.4% vs. 70.1%, respectively). However, the differences were not statistically significant. Conclusions: Maxillectomy guided by 3D printing may offer enhanced surgical precision and improved local control in patients undergoing head and neck cancer surgeries. Further research with larger cohorts is necessary to confirm these findings. Full article

Background: The purpose of the study was to describe proportional condylectomy in patients with condylar hyperplasia using a titanium 3D-printed ultrathin wire mesh cutting guide placed below the planned bone resection. Methods: Eight patients with condylar hyperplasia underwent proportional condylectomy using an ultrathin titanium 3D-printed cutting guide placed below the planned bone resection. The placement of the guide was facilitated by the incorporation of anatomical landmarks. The accuracy of bone resections guided by such devices was evaluated on postoperative radiographs. The mean postoperative follow-up was 30 months. Results: Surgery could be performed in all patients in the same manner as virtually planned. The fitting accuracy of the cutting guides was judged as good. Postoperative radiographs revealed that the virtually planned shape of the newly formed condylar head after condylectomy could be achieved. Conclusions: In conclusion, the use of virtual computer-assisted planning and CAD/CAM-based cutting guides for proportional condylectomy in unilateral condylar hyperplasia of the mandible offers high accuracy and guarantees very predictable results. Full article

Objectives: Buccal cortical bone dimensions are crucial in dental radiology, as they impact orthodontic treatment outcomes. Changes in alveolar bone dimensions can result in malocclusion and require interdisciplinary approaches for correction. The accurate quantification of buccal bone dimensions is crucial for appropriate treatment planning and avoiding medico-legal issues. This study aimed to compare buccal bone height measurements between three-dimensional (3D) digital imaging and communications in medicine (DICOM) data and portable document format (PDF) cone beam computer topography reports for mandibular frontal teeth, testing the hypothesis of no difference in values between the two modalities. Methods: Each of the five observers performed a total of 720 height measurements (360 by DICOM and 360 by PDF), yielding a total of 3600 measurements overall. Results: Compared with the DICOM format, using PDF files was associated with a significantly greater rate of inability to carry out the measurements (8.8% vs. 3%, respectively, p < 0.001, chi-square). The average buccal bone height measured in the DICOM was 11.51 mm, which was significantly greater than the 10.35 mm measured in the PDF (p < 0.001). The mean height measured by the DICOM was consistently greater than that measured by the PDF, with highly significant differences in the findings of four of the examiners (p < 0.001). Conclusions: Viewing modality significantly affected the height of the buccal bone in the frontal mandibular area. Compared with the generated PDF reports, the 3D DICOM viewer performed better than the printed PDF and enabled more measurements in the target area. Full article

This study evaluated the microbial growth profile of subgingival multispecies biofilm on 3D-printable resin-based composites (PRBCs). A 96-well cell plate cultivated a 39-species biofilm associated with periodontitis over 7 days. Cylindrical specimens with 12 mm high and 3 mm diameters were prepared by the PRBC group (Cosmos Temp-Yller; Prizma 3D Bio Crown; Prizma 3D Bio Prov) and an acrylic resin as control. Further, these specimens were immersed in the well plate to allow biofilm formation. After growing for 7 days, the metabolic biofilm activity was evaluated by colorimetric assay and the microbial profile by DNA-DNA hybridization. Kruskal–Wallis and Mann–Whitney tests evaluated each bacteria count and complex group. A greater biofilm formation was observed on PRBC groups than on acrylic resin. The microbiological profile of PRBC was associated with a less pathogenic biofilm, with an absence of a red complex. Acrylic resin showed low biofilm growth, but the biofilm profile was related to periodontal disease, characterized by red-complex bacteria. The selection of PRBC may contribute more effectively to maintaining periodontal health than acrylic resin. Full article

This article presents the authors’ design of an electronic stethoscope intended for use during online medical consultations for patient auscultation. The goal of the project was to design an instrument that is durable, user-friendly, and affordable. Existing electronic components were used to create the device and a traditional single-sided chest piece. Three-dimensional printing technology was employed to manufacture the prototype. Following the selection of the material, a static tensile strength test was conducted on the printed samples as part of the pre-implementation investigations. Results: Tests on samples made of PLA with a 50% hexagonal infill demonstrated a tensile strength of 36 MPa and an elongation of 4–5%, which was deemed satisfactory for the intended application in the stethoscope’s manufacture. The designed and manufactured electronic stethoscope presented in the article can be connected to headphones or speakers, enabling remote medical consultation. According to the opinion of doctors who tested it, it provides the appropriate sound quality for auscultation. This stethoscope facilitates the rapid detection and recognition of cardiac and respiratory activity in humans. Full article

Additive manufacturing (AM) processes, such as fused deposition modelling (FDM), have emerged as transformative technologies in pharmaceutical manufacturing, enabling the production of drug delivery systems with complex and customised geometries. These advancements provide precise control over drug release profiles and facilitate the development of patient-specific medicines. This study investigates the dissolution behaviour of AM-fabricated tablets made from polyvinyl alcohol (PVA), a hydrophilic and biocompatible polymer widely used in drug delivery systems. The influence of the initial mass, surface area, and surface-area-to-volume ratio (S/V) on dissolution kinetics is evaluated for tablets with intricate geometries. Our findings demonstrate that these parameters, while critical for conventional tablet shapes, are insufficient to fully predict the dissolution behaviour of complex geometries. Furthermore, this study highlights how geometric modifications can enable the administration of the same drug dosage through sustained or immediate release profiles, offering enhanced versatility in drug delivery. By leveraging the geometric design freedom provided by AM technologies, this research underscores the potential for optimising drug delivery systems to improve therapeutic outcomes and patient compliance. Full article

This review summarizes the recent advancements in the mechanical properties of nanocomposites reinforced with surface-modified carbon nanotubes (CNTs). A range of matrices, namely, polymers, metals, and cement, is investigated, which have demonstrated increasing importance in a broad range of industrial sectors, such as 3D printing, automotive, construction, and coatings. The strengthening mechanisms that CNTs impart in composites are reviewed, and synergistic effects with their surface groups or co-additives are analyzed, including wettability, mechanical interlocking, and chemical bonding. Different mechanical and functional properties of the CNT-reinforced nanocomposites are analyzed, such as tensile strength, flexural strength, impact resistance, thermal conductivity, and electrical conductivity. The improvements in these properties for a variety of CNT-based composites are presented, and details on how these improvements were attained are discussed. The review concludes that surface modification of CNTs has proven to be of high importance, enhancing compatibility with various matrices and facilitating improvements in the nanocomposite properties. Suggestions for viable CNT-based composites for use in the studied applications are also provided. Full article

Obtaining reliable dynamic mechanical properties through experiments is essential for developing and validating constitutive models in material selection and structural design. This study introduces a dynamic tensile method using a modified M-type specimen loaded by a split Hopkinson pressure bar (SHPB). A closed M-type specimen was thus employed. Finite element simulations and experiments were used to validate the design of the M-type specimen, which was fabricated using 17-4PH (precipitation hardening) stainless steel powder with a 3D (three-dimensional) selected laser melting (SLM) printer. After verifying force balance and uniform deformation in the tensile region, tensile tests were conducted across strain rates from quasi-static to a strain rate of 5900 s⁻¹. The results demonstrated that this method effectively assessed the dynamic tensile behaviors of stainless steel at high strain rates, and achieved both ultra-high strain rates and large plastic deformation. Full article

Recent studies have identified microneedle (MN) arrays as promising alternatives for transdermal drug delivery. This study investigated the properties of novel staggered MN arrays design featuring two distinct heights of MNs. The staggered MN arrays were precisely fabricated via PμSL light-cured 3D printing technology. The arrays were systematically evaluated for their morphology, fracture force, skin penetration ability, penetration mechanism, and drug delivery capability. The results demonstrated that the staggered MN arrays punctured the skin incrementally, leveraging the benefits of skin deformation during the puncture process. This approach effectively reduced the puncture force needed, achieving a maximum reduction of approximately 80.27% due to variations in the staggered height. Additionally, the staggered design facilitated skin penetration, as confirmed by the results of the rat skin hematoxylin-eosin (H&E) staining experiments. Compared with 3D-printed planar structures and highly uniform MN arrays, the staggered design exhibited enhanced hydrophilicity, as evidenced by a reduction in the contact angle from approximately 93° to 70°. Simulated drug release images of both coated and hollow staggered MNs illustrated the release and delivery capabilities of these structures across various skin layers, and the staggered design expanded the effective area of the MN arrays within the vertical dimension of the skin layers. This study offers both experimental and theoretical foundations for developing MN arrays with three–dimensional structural distributions, thereby facilitating advancements in MN array technology. Full article

This study focuses on selecting a suitable 3D printer and defining experimental methods to gather the necessary data for determining the optimal filament material for printing components of the VEX GO and VEX IQ robotic kits. The aim is to obtain the required data to identify an appropriate filament material and set 3D printing parameters to achieve the desired mechanical properties of the parts while maintaining cost-effectiveness. Another key objective is achieving optimal operational functionality, ensuring the required part performance with minimal printing costs. It is desirable for the modeled and printed parts to exhibit the required mechanical properties while maintaining economic efficiency. Another crucial aspect is achieving optimal functionality of the produced parts with minimal printing costs. This will be assessed by analyzing the impact of key 3D printing technology parameters, focusing in this research phase on material selection. The criteria for selecting filament materials include ease of printability under the conditions of primary and secondary schools, simplicity of printing, minimal need for post-processing, and adequate mechanical properties verified through experimental measurements and destructive tests on original parts from VEX GO and VEX IQ kits. The study analyzed various filaments regarding their mechanical properties, printability, and cost-effectiveness. The most significant practical contribution of this study is selecting a suitable filament material tested through a set of destructive tests, emphasizing maintaining the mechanical properties required for the real-life application of the parts. This includes repetitive assembly and disassembly of various robotic model constructions and their activation for demonstration purposes and applications of STEM/STEAM/STREAM methods in the educational process to achieve the properties of original components. Additionally, the study aims to set up 3D printing such that even a beginner-level operator, such as a primary or secondary school student under the supervision of their teacher or a teacher with minimal knowledge and experience in 3D printing, can successfully execute it. Further ongoing research focuses on evaluating the effects of characteristic 3D printing parameters, such as infill and perimeter, on the properties of 3D-printed parts through additional measurements and analyses. Full article

A composite material based on polyvinyl alcohol (PVA) and brookite-phase titanium dioxide (TiO₂) was synthesized using a straightforward method that involved combining the polymer with a sol as a filler. The composites were analyzed using Fourier transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimetry (DSC), and mechanical testing. The effects of treating the sol with underwater discharge plasma utilizing different electrode materials on the surface morphology, mechanical properties, thermal stability, and optical (photochromic) characteristics of the composites were investigated. FTIR spectral analysis indicated the presence of a chemical bond between the polymer matrix and the filler particles, as evidenced by the appearance of new peaks in the region of 700–500 cm⁻¹. Preliminary plasma treatment was shown to enhance the thermal stability, strength, and elasticity of the PVA-based composite. These improvements resulted from the modification of the filler (sol) due to plasma activity. The resulting composites exhibited a low photocolorization rate and a high bleaching rate. Such composites represent a promising material for use as inks in 3D printing. Full article

Polymeric materials made from renewable sources that can biodegrade in the environment are attracting considerable attention as substitutes for petroleum-based polymers in many fields, including additive manufacturing and, in particular, Fused Deposition Modelling (FDM). Among the others, poly(hydroxyalkanoates) (PHAs) hold significant potential as candidates for FDM since they meet the sustainability and biodegradability standards mentioned above. However, the most utilised PHA, consisting of the poly(hydroxybutyrate) (PHB) homopolymer, has a high degree of crystallinity and low thermal stability near the melting point. As a result, its application in FDM has not yet attained mainstream adoption. Introducing a monomer with higher excluded volume, such as hydroxyvalerate, in the PHB primary structure, as in poly(hydroxybutyrate-co-valerate) (PHBV) copolymers, reduces the degree of crystallinity and the melting temperature, hence improving the PHA printability. Blending amorphous poly(lactic acid) (PLA) with PHBV enhances further PHA printability via FDM. In this work, we investigated the printability of two blends characterised by different PLA and PHBV weight ratios (25:75 and 50:50), revealing the close connection between blend microstructures, melt rheology and 3D printability. For instance, the relaxation time associated with die swelling upon extrusion determines the diameter of the extruded filament, while the viscoelastic properties the range of extrusion speed available. Through thoroughly screening printing parameters such as deposition speed, nozzle diameter, flow percentage and deposition platform temperature, we determined the optimal printing conditions for the two PLA/PHBV blends. It turned out that the blend with a 50:50 weight ratio could be printed faster and with higher accuracy. Such a conclusion was validated by replicating with remarkable fidelity high-complexity objects, such as a patient’s cancer-affected iliac crest model. Full article

Coal fly ash zeolites with Sodalite structure were synthesized by ultrasound-assisted double stage fusion-hydrothermal synthesis. Monometallic Ni and bimetallic Ni–Cu supported catalysts with 5 wt.% Ni and different copper contents of 1.5, 2.5 and 5.0 wt.% Cu were prepared by post-synthesis incipient wetness impregnation. The catalysts were characterized by X-ray powder diffraction, N₂ physisorption, transmission electron microscopy (TEM), Mössbauer spectroscopy and H₂ temperature programmed reduction analysis. It was found that crystalline Cu⁰ and Ni_xCu_y intermetallic nanoparticles were formed in the reduced powder and 3D printed catalysts and that they affected the reducibility of the catalytically active nickel phase. Three-dimensionally printed 5Ni2.5Cu/Sodalite catalysts were prepared via modification with metals before and after 3D printing for comparative studies. The powder and 3D printed catalysts were studied in the lignocellulosic biomass-derived levulinic acid (LA) to γ-valerolactone (GVL). The formation of NiCu alloy, which is found on the powder and 3D printed catalysts, favors their catalytic performance in the studied reaction. In contrast with powder catalysts, the preservation of the Sodalite structure was detected for all 3D printed samples and was found to have a positive influence on the metal dispersion registered in the 3D spent catalysts. The powder 5Ni2.5Cu/Sodalite catalyst showed the highest LA conversion and high GVL yield at 150 °C reaction temperature. Three-dimensionally printed catalysts show more stable catalytic activity than powder catalysts due to the preservation of the zeolite structure and metal dispersion. Full article