Novel 3D printed bioactive SiC orthopedic screw promotes bone growth associated activities by macrophages, neurons, and osteoblasts.

Ceramic additive manufacturing currently relies on binders or high-energy lasers, each with limitations affecting final product quality and suitability for medical applications. To address these challenges, our laboratory has devised a surface activation technique for ceramic particles that eliminates the necessity for polymer binders or high-energy lasers in ceramic additive manufacturing. We utilized this method to 3D print bioactive SiC orthopedic screws and evaluated their properties. The study's findings reveal that chemical oxidation of SiC activated its surface, enabling 3D printing of orthopedic screws in a binder jet printer. Post-processing impregnation with NaOH and/or NH4OH strengthened the scaffold by promoting silica crystallization or partial conversion of silicon oxide into silicon nitride. The silica surface of the SiC 3D printed orthopedic screws facilitated osteoblast and neuron adhesion and extensive axon synthesis. The silicate ions released from the 3D printed SiC screws favorably modulated macrophage immune responses toward an M1 phenotype as indicated by the inhibition of TNFα secretions and of reactive oxygen species (ROS) expression along with the promotion of IL6R shedding. In contrast, under the same experimental conditions, Ti ions released from Ti6Al4V discs promoted macrophage TNFα secretion and ROS expression. In vivo tests demonstrated direct bone deposition on the SiC scaffold and a strong interfacial bond between the implanted SiC and bone. Immunostaining showed innervation, mineralization, and vascularization of the newly formed bone at the interface with SiC. Taken altogether, the 3D printed SiC orthopedic screws foster a favorable environment for wound healing and bone regeneration. The novel 3D printing method, based on ceramic surface activation represents a significant advancement in ceramic additive manufacturing and is applicable to a wide variety of materials.

Synthetic Bone Blocks Produced by Additive Manufacturing in the Repair of Critical Bone Defects.

This study evaluated the efficacy of synthetic bone blocks, composed of hydroxyapatite (HA) or ß-tricalcium phosphate (B-TCP), which were produced by additive manufacturing and used for the repair of critical size bone defects (CSDs) in rat calvaria. Sixty rats were divided into five groups (n = 12): blood clot (CONTROL), 3D-printed HA (HA), 3D-printed ß-TCP (B-TCP), 3D-printed HA + autologous micrograft (HA+RIG), and 3D-printed ß-TCP + autologous micrograft (B-TCP+RIG). CSDs were surgically created in the parietal bone and treated with the respective biomaterials. The animals were euthanized at 30 and 60 days postsurgery for microcomputed tomography (micro-CT) histomorphometric, and immunohistochemical analysis to assess new bone formation. Micro-CT analysis showed that both biomaterials were incorporated into the animals' calvaria. The HA+RIG group, especially at 60 days, exhibited a significant increase in bone formation compared with the control. The use of 3D-printed bioceramics resulted in thinner trabeculae but a higher number of trabeculae compared with the control. Histomorphometric analysis showed bone islands in close contact with the B-TCP and HA blocks at 30 days. The HA blocks (HA and HA+RIG groups) showed statistically higher new bone formation values with further improvement when autologous micrografts were included. Immunohistochemical analysis showed the expression of bone repair proteins. At 30 days, the HA+RIG group had moderate Osteopontin (OPN) staining, indicating that the repair process had started, whereas other groups showed no staining. At 60 days, the HA+RIG group showed slight staining, similar to that of the control. Osteocalcin (OCN) staining, indicating osteoblastic activity, showed moderate expression in the HA and HA+RIG groups at 30 days, with slight expression in the B-TCP and B-TCP+RIG groups. The combination of HA blocks with autologous micrografts significantly enhanced bone repair, suggesting that the presence of progenitor cells and growth factors in the micrografts contributed to the improved outcomes. It was concluded that 3D-printed bone substitute blocks, associated with autologous micrografts, are highly effective in promoting bone repair in CSDs in rat calvaria.

3D printing of Pickering emulsions, Pickering foams and capillary suspensions - A review of stabilization, rheology and applications.

Pickering emulsions and foams as well as capillary suspensions are becoming increasingly more popular as inks for 3D printing. However, a lack of understanding of the bulk rheological properties needed for their application in 3D printing is potentially stifling growth in the area, hence the timeliness of this review. Herein, we review the stability and bulk rheology of these materials as well as the applications of their 3D-printed products. By highlighting how the bulk rheology is tuned, and specifically the inks storage modulus, yield stress and critical balance between the two, we present a rheological performance map showing regions where good prints and slumps are observed thus providing clear guidance for future ink formulations. To further advance this field, we also suggest standard experimental protocols for characterizing the bulk rheology of the three types of ink: capillary suspension, Pickering emulsion and Pickering foam for 3D printing by direct ink writing.

Progress in Additive Manufacturing of Magnesium Alloys: A Review.

Magnesium alloys, renowned for their lightweight yet high-strength characteristics, with exceptional mechanical properties, are highly coveted for numerous applications. The emergence of magnesium alloy additive manufacturing (Mg AM) has further propelled their popularity, offering advantages such as unparalleled precision, swift production rates, enhanced design freedom, and optimized material utilization. This technology holds immense potential in fabricating intricate geometries, complex internal structures, and performance-tailored microstructures, enabling groundbreaking applications. In this paper, we delve into the core processes and pivotal influencing factors of the current techniques employed in Mg AM, including selective laser melting (SLM), electron beam melting (EBM), wire arc additive manufacturing (WAAM), binder jetting (BJ), friction stir additive manufacturing (FSAM), and indirect additive manufacturing (I-AM). Laser powder bed fusion (LPBF) excels in precision but is limited by a low deposition rate and chamber size; WAAM offers cost-effectiveness, high efficiency, and scalability for large components; BJ enables precise material deposition for customized parts with environmental benefits; FSAM achieves fine grain sizes, low defect rates, and potential for precision products; and I-AM boasts a high build rate and industrial adaptability but is less studied recently. This paper attempts to explore the possibilities and challenges for future research in AM. Among them, two issues are how to mix different AM applications and how to use the integration of Internet technologies, machine learning, and process modeling with AM, which are innovative breakthroughs in AM.

The Journey of Additive Manufacturing in Prosthodontics from the Early Dawn till the Current State of Art. A Narrative Review.

Additive manufacturing (AM) also known as 3D-printing has become one of the pillars of digital technology in the dental field particularly in prosthodontics. With the burgeoning development in the already existing AM technology and the evolution of new techniques, concurrent with the development of printable biomaterials, the range of application of the technology has broadened from the construction of diagnostic models to more complex applications such as maxillofacial prosthetics and implant planning. Full understanding of the technology and the related fabrication parameters will enable the maximum benefit from such technology. Therefore, the aim of this review is to represent a road trip along which the prosthodontists and dental technicians can cast a closer look on different AM technologies, advantages and disadvantages of each technique, the application of technology in the field of Prosthodontics, areas of current research in the field and finally recommendations for areas of future investigations.

Adaptive Fabrication of Electrochemical Chips with a Paste-Dispensing 3D Printer.

Electrochemical (EC) detection is a powerful tool supporting simple, low-cost, and rapid analysis. Although screen printing is commonly used to mass fabricate disposable EC chips, its mask is relatively expensive. In this research, we demonstrated a method for fabricating three-electrode EC chips using 3D printing of relatively high-viscosity paste. The electrodes consisted of two layers, with carbon paste printed over silver/silver chloride paste, and the printed EC chips were baked at 70 °C for 1 h. Engineering challenges such as bulging of the tubing, clogging of the nozzle, dripping, and local accumulation of paste were solved by material selection for the tube and nozzle, and process optimization in 3D printing. The EC chips demonstrated good reversibility in redox reactions through cyclic voltammetry tests, and reliably detected heavy metal ions Pb(II) and Cd(II) in solutions using differential pulse anodic stripping voltammetry measurements. The results indicate that by optimizing the 3D printing of paste, EC chips can be obtained by maskless and flexible 3D printing techniques in lieu of screen printing.

Additively manufactured bioceramic scaffolds based on triply periodic minimal surfaces for bone regeneration.

The study focused on the effects of a triply periodic minimal surface (TPMS) scaffolds, varying in porosity, on the repair of mandibular defects in New Zealand white rabbits. Four TPMS configurations (40%, 50%, 60%, and 70% porosity) were fabricated with ß-tricalcium phosphate bioceramic via additive manufacturing. Scaffold properties were assessed through scanning electron microscopy and mechanical testing. For proliferation and adhesion assays, mouse bone marrow stem cells (BMSCs) were cultured on these scaffolds. In vivo, the scaffolds were implanted into rabbit mandibular defects for 2 months. Histological staining evaluated osteogenic potential. Moreover, RNA-sequencing analysis and RT-qPCR revealed the significant involvement of angiogenesis-related factors and Hippo signaling pathway in influencing BMSCs behavior. Notably, the 70% porosity TPMS scaffold exhibited optimal compressive strength, superior cell proliferation, adhesion, and significantly enhanced osteogenesis and angiogenesis. These findings underscore the substantial potential of 70% porosity TPMS scaffolds in effectively promoting bone regeneration within mandibular defects.

3D printing of electrochemical cell for voltammetric detection and photodegradation monitoring of folic acid in juice samples.

In this study, compact 3D-printed carbon black (CB) electrodes were manufactured for using in folic acid (FA) analysis in fruit samples. Before application in FA analysis, the electrode surfaces were characterized by high-resolution scanning electron microscopy and voltammetry using well-known redox probes. Square wave voltammetric study presented linear responses in the range between 10 and 200 µmol/L (R2 > 0.99), exhibited a suitable detection limit (LOD) of âˆ¼ 5.1 µmol/L and acceptable performance in terms of reproducibility and anti-interference experiments. The analysis of FA in four different food samples using the proposed method agreed statistically with a comparative technique based on spectrophotometric measurements. Moreover, results from photostability experiments indicated that FA can be degraded after 5 and 20 min of UV exposure. These results successfully demonstrated the analytical feasibility of the 3D-printed electrodes as sensing material and for monitoring the photostability of FA in different fruit matrices.

Application of a 3D bioprinter: jet technology for 'biopatch' development using cells on hydrogel supports.

Additive manufacturing (3D printing) has been deployed across multiple platforms to fabricate bioengineered tissues. We demonstrate the use of a Thermal Inkjet Pipette System (TIPS) for targeted delivery of cells onto manufactured substrates to design bio-bandages. Two cell lines - HEK 293 (kidney) and K7M2 wt (bone) - were applied using TIPS. We demonstrate a novel means for targeted cell delivery to a hydrogel support structure. These cell/support constructs (bio-bandages) had a high viability for survival and growth over extended periods. Combining a flexible biosupport with application of cells via TIPS printing now for the first time allows for custom cell substrate constructs with various densities to be deployed for regenerative medicine applications.

The exosomal secretomes of mesenchymal stem cells extracted via 3D-printed lithium-doped calcium silicate scaffolds promote osteochondral regeneration.

The development of surface modification techniques has brought about a major paradigm shift in the clinical applications of bone tissue regeneration. Biofabrication strategies enable the creation of scaffolds with specific microstructural environments and biological components. Lithium (Li) has been reported to exhibit anti-inflammatory, osteogenic, and chondrogenic properties by promoting several intracellular signaling pathways. Currently, research focuses on fabricating scaffolds with simultaneous dual bioactivities to enhance osteochondral regeneration. In this study, we modified the surface of calcium silicate (CS) scaffolds with Li using a simple immersion technique and evaluated their capabilities for bone regeneration. The results showed that Li ions could be easily coated onto the surfaces of CS scaffolds without affecting the microstructural properties of CS itself. Furthermore, the modifications did not affect the printing capabilities of the CS, and porous scaffolds could be fabricated via extrusion. Moreover, the presence of Li improved the surface roughness and hydrophilicity, thus leading to enhanced secretion of osteochondral-related regeneration factors, such as alkaline phosphatase (ALP), bone sialoprotein (BSP), and collagen II (Col II) proteins. Subsequent in vivo studies, including histological and micro-CT analyses, confirmed that the Li-modified CS scaffolds promoted osteochondral regeneration. The transcriptome analysis suggested that the enhanced osteochondrogenic capabilities of our scaffolds were influenced by paracrine exosomes. We hope this study will inspire further research on osteochondral regeneration.

The mechanical properties of dissimilar/similar polymer materials joined by friction stir welding.

Joining dissimilar materials is important in engineering studies to reduce costs, lighten structures, and take advantage of the superior properties of the materials. However, the different chemical compositions, physical, and mechanical properties of dissimilar materials make the joining process difficult. To overcome the limitations of traditional joining techniques, there is an increasing interest towards innovative welding methods such as ultrasonic welding, laser welding, friction stir welding, and so on. In this study, friction stir welding was used to join different types of polymer materials. Polylactic acid (PLA Plus) plates were 3D printed and welded with High Density Polyethylene (HDPE) to create PLA Plus/PLA Plus, HDPE/HDPE, and PLA Plus/HDPE connection pairs. Two different pin profiles (triangle and square), rotational speed (1000 and 1500 rpm) and feed rate (30 and 50 mm/min) were used in the FSW process. Tensile tests were performed to determine the weld strength after FSW. In addition, the hardness changes in the heat-affected zone and in the weld zone were evaluated. Finally, optical inspections were made on the welded samples to identify welding defects. The results showed that the highest weld strength was obtained with the triangular pin profile in PLA Plus/PLA Plus and PLA Plus/HDPE material pairs, and while with the square pin profile in HDPE-HDPE pairs. PLA Plus has been found to be a more suitable material for Friction Stir Welding compared to HDPE. Welding defects caused by changes in welding speed and tool rotation speed were identified in the material pairs.

Electrochemical sensor based on 3D-printed substrate by masked stereolithography (MSLA): a new, cheap, robust and sustainable approach for simple production of analytical platforms.

The development of miniaturized, sustainable and eco-friendly analytical sensors with low production cost is a current trend worldwide. Within this idea, this work presents  the innovative use of masked stereolithography (MSLA) 3D-printed substrates for the easy fabrication of pencil-drawn electrochemical sensors (MSLA-3D-PDE). The use of a non-toxic material such as pencil (electrodes) together with a biodegradable 3D printing resin (substrate) allowed the production of devices that are quite cheap (ca. US$ 0.11 per sensor) and with low environmental impact. Compared to paper, which is the most used substrate for manufacturing pencil-drawn electrodes, the MSLA-3D-printed substrate has the advantages of not absorbing water (hydrophobicity) or becoming crinkled and weakened when in contact with solutions. These features provide more reproducible, reliable, stable, and long-lasting sensors. The MSLA-3D-PDE, in conjunction with the custom cell developed, showed excellent robustness and electrochemical performance similar to that observed of the glassy carbon electrode, without the need of any activation procedure. The analytical applicability of this platform was explored through the quantification of omeprazole in pharmaceuticals. A limit of detection (LOD) of 0.72 µmol L-1 was achieved, with a linear range of 10 to 200 µmol L-1. Analysis of real samples provided results that were highly concordant with those obtained by UV-Vis spectrophotometry (relative error ≤ 1.50%). In addition, the greenness of this approach was evaluated and confirmed by a quantitative methodology (Eco-Scale index). Thus, the MSLA-3D-PDE appears as a new and sustainable tool with great potential of use in analytical electrochemistry.

Finite element analysis of optimized novel additively manufactured non-articulating prostheses for cervical total disc replacement.

Ball-and-socket designs of cervical total disc replacement (TDR) have been popular in recent years despite the disadvantages of polyethylene wear, heterotrophic ossification, increased facet contact force, and implant subsidence. In this study, a non-articulating, additively manufactured hybrid TDR with an ultra-high molecular weight polyethylene core and polycarbonate urethane (PCU) fiber jacket, was designed to mimic the motion of normal discs. A finite element (FE) study was conducted to optimize the lattice structure and assess the biomechanical performance of this new generation TDR with an intact disc and a commercial ball-and-socket Baguera®C TDR (Spineart SA, Geneva, Switzerland) on an intact C5-6 cervical spinal model. The lattice structure of the PCU fiber was constructed using the Tesseract or the Cross structures from the IntraLattice model in the Rhino software (McNeel North America, Seattle, WA) to create the hybrid I and hybrid II groups, respectively. The circumferential area of the PCU fiber was divided into three regions (anterior, lateral and posterior), and the cellular structures were adjusted. Optimal cellular distributions and structures were A2L5P2 in the hybrid I and A2L7P3 in the hybrid II groups. All but one of the maximum von Mises stresses were within the yield strength of the PCU material. The range of motions, facet joint stress, C6 vertebral superior endplate stress and path of instantaneous center of rotation of the hybrid I and II groups were closer to those of the intact group than those of the Baguera®C group under 100 N follower load and pure moment of 1.5 Nm in four different planar motions. Restoration of normal cervical spinal kinematics and prevention of implant subsidence could be observed from the FE analysis results. Superior stress distribution in the PCU fiber and core in the hybrid II group revealed that the Cross lattice structure of a PCU fiber jacket could be a choice for a next-generation TDR. This promising outcome suggests the feasibility of implanting an additively manufactured multi-material artificial disc that allows for better physiological motion than the current ball-and-socket design.

An exploratory study of topographical signatures within 3D fused deposition modelling using Polylactic Acid (PLA) filament.

This preliminary limited study considers the possibility of the same source identification of consecutively 3D printed components using polymer filament by the examination of deposition artifacts as distinctive macroscopic and microscopic surface characteristics upon the surface of 3D printed objects. Hot-end printer nozzle deposition using polymer filaments can create distinctive surface characteristics upon 3D FDM-printed manufactured objects that can be identified, examined, and compared. Such artifacts can occur as repeatable patterns known as 'deposition striae', 'detachment points', and 'start points' upon the surfaces of an object and on consecutively manufactured components that have used the same 3D Fused Deposition Modelling (FDM) printer hardware. Some of these observable artifacts can fulfil the sufficient agreement requirements of the Association of Firearm and Tool Mark Examiners (AFTE) Theory of Identification as it relates to tool marks when applied to consecutively produced 3D Additive Manufacture (AM) components. For this criteria to apply, the influence of subclass characteristics on any identification must be ruled out.

The Impact of Particle Size and Surface Treatment of Zirconia Suspension for Photocuring Additive Manufacturing.

To prepare a photocurable ceramic suspension for use in commercialized additive manufacturing equipment, the effects of the rheological properties of zirconia particles added to a binder, and the presence or absence of a silane coupling agent on the particles was evaluated. To this end, three experimental groups (ZSs, ZMs, ZLs) and three control groups (ZS, ZM, ZL) were designed depending on the size of the underlying zirconia particles. The test-group zirconia suspensions were prepared through silanization, which was not applied to the control-group suspensions. Depending on the particle size, viscosity differences between the test and control groups were 16,842, 18,623, and 12,303 mPa·s, respectively. Compared to the other groups, the viscosity of the ZLs group suspension decreased by 70.98-88.04%. This confirmed that the viscosity of the suspensions was affected by the particle size and the presence of silane coating. The dispersion stability of the zirconia suspensions was evaluated over 20 days. A sedimentation test confirmed that the sedimentation rate of the ZLs group was slower than those of the other groups. This study aimed to optimize the suspension manufacturing method to effectively be utilized in further commercializing zirconia three-dimensional (3D) printing and could also help to develop various medical applications.

Creativity and Generation of Ideas in the Design of Children's Toys.

Creativity offers new, interesting, and valuable things that can be intangible (ideas, a theory, songs, etc.) or physical objects (a painting, invention, machine). Creativity implies a lot of qualities of the creator such as imagination, creative work, and innovation and it also improves learning and memory. Many of history's most important discoveries are the results of creative activity. Repetition leads to mastery of a concept through understanding and produces increased self-confidence. Confidence increases the willingness to act on creativity-to explore, discover, and learn. This positive cycle of learning is fueled by the curiosity and enjoyment that comes from discovery and understanding. We are social creatures, so the greatest reward and pleasure comes from the admiration and support received from loved and respected people. Stimulating children's interest through play also defines solving through exploration regarding the accumulation of new essential information for knowing values and other useful information, by stimulating curiosity and creativity as well as discovering new resources that generate creative ideas, allowing the acquisition of practical skills. All these aspects are oriented and define the premises for the harmonious development of children towards a new existential stage. Thus, taking these aspects into account will have future effects on self-confidence, work strategies, school results, as well as the desire to study and the ability to store and organize accumulated information. The approach of the case study presents through the game, a motivational alternative, staged regarding the generation of creative ideas in the development and materialization of the concept. It is well known that during childhood, many things are acquired by children through selective association and depending on the sensory perception of objects, namely preferred colors, functions, and predefined shapes, proportional to the anthropometric dimensions specific to preschool age. The article proposes the creative approach and generation of ideas on the design of children's toys; namely, a case study is presented: children's toy set-teacup.

Electrochemical Replication and Transfer for Low-Cost, Sub-100 nm Patterning of Materials on Flexible Substrates.

The fabrication of high-resolution patterns on flexible substrates is an essential step in the development of flexible electronics. However, the patterning process on flexible substrates often requires expensive equipment and tedious lithographic processing. Here, a bottom-up patterning technique, termed electrochemical replication and transfer (ERT) is reported, which fabricates multiscale patterns of a wide variety of materials by selective electrodeposition of target materials on a predefined template, and subsequent transfer of the electrodeposited materials to a flexible substrate, while leaving the undamaged template for reuse for over 100 times. The additive and parallel patterning attribute of ERT allows the fabrication of multiscale patterns with resolutions spanning from sub-100 nm to many centimeters simultaneously, which overcomes the trade-off between resolution and throughput of conventional patterning techniques. ERT is suitable for fabricating a wide variety of materials including metals, semiconductors, metal oxides, and polymers into arbitrary shapes on flexible substrates at a very low cost.

Direct CO2 Capture by Alkali-Dissolved Cellulose and Sequestration in Building Materials and Artificial Reef Structures.

Current carbon capture and utilization (CCU) technologies require high energy input and costly catalysts. Here, an effective pathway is offered that addresses climate action by atmospheric CO2 sequestration. Industrially relevant highly reactive alkali cellulose solutions are used as CO2 absorption media. The latter lead to mineralized cellulose materials (MCM) at a tailorable cellulose-to-mineral ratio, forming organic-inorganic viscous systems (viscosity from 102 to 107  mPa s and storage modulus from 10 to 105  Pa). CO2 absorption and conversion into calcium carbonate and associated minerals translate to maximum absorption of 6.5 gCO2 gcellulose -1 , tracking inversely with cellulose loading. Cellulose lean gels are easily converted into dry powders, shown as a functional component of ceramic glazes and cementitious composites. Meanwhile, cellulose-rich gels are moldable and extrudable, yielding stone-like structures tested as artificial substrates for coral reef restoration. Life Cycle Assessment (LCA) suggests new CCU opportunities for building materials, as demonstrated in underwater deployment for coral reef ecosystem restoration.

Surface Characteristics and Flexural Strength of Porous-Surface Designed Zirconia Manufactured via Stereolithography.

PURPOSE: To design and fabricate zirconia bars with porous surfaces using stereolithography and evaluate their surface characteristics and flexural strengths. MATERIALS AND METHODS: Five groups of zirconia bars (20 mm × 4 mm × 2 mm) with interconnected porous surfaces were designed and manufactured: (i) 400-µm pore size and 50% porosity (D400-P50 group), (ii) 400-µm pore size and 30% porosity (D400-P30 group), (iii) 200-µm pore size and 50% porosity (D200-P50 group), (iv) 200-µm pore size and 30% porosity (D200-P30 group), and (v) 100-µm pore size and 30% porosity (D100-P30 group). Zirconia bars without a porous surface (NP) were used as controls. The surface topographies and pore structures were investigated using scanning electron microscopy and three-dimensional laser microscopy. The printed porosity was calculated using the Archimedes method. Fifteen specimens from each group were subjected to a three-point bending test according to the ISO 6872:2015 standard. A Weibull analysis was performed, and the fractured surfaces were examined using scanning electron microscopy. RESULTS: Zirconia bars with porous surfaces were designed and successfully manufactured. The designed pore size, porosity, and shape of the printed pores were approximately achieved for all the porous surfaces. The flexural strength of the control group was significantly higher than those of the groups with porous surfaces (p < 0.001). For the same porosity, groups with a pore size of 400 µm exhibited a lower flexural strength than the other groups (p<0.001). Additionally, for the same pore-size design, the flexural strengths of group D400-P50 and D400-P30 exhibited no significant differences (p = 0.150), while the flexural strengths of D200-P30 were significantly higher than that of the D200-P50 group (p = 0.043). The control group and D400-P50 group had higher Weibull moduli than the other groups. The fractography of the specimens with porous surfaces indicated more than one crack origin, mainly owing to defects, including pores and cracks. CONCLUSION: Zirconia bars with porous surfaces were successfully designed and fabricated using the stereolithography technique. Although porous surfaces may be advantageous for osteogenesis, the porous-surface design can reduce the flexural strength of the printed zirconia bars. By reducing the pore size, controlling the porosity, and improving the printing accuracy, a higher strength can be achieved.

Combined Effects of Polydopamine-Assisted Copper Immobilization on 3D-Printed Porous Ti6Al4V Scaffold for Angiogenic and Osteogenic Bone Regeneration.

Numerous studies have demonstrated that biological compounds and trace elements such as dopamine (DA) and copper ions (Cu) could be modified onto the surfaces of scaffolds using a one-step immersion process which is simple, inexpensive and, most importantly, non-cytotoxic. The development and emergence of 3D printing technologies such as selective laser melting (SLM) have also made it possible for us to fabricate bone scaffolds with precise structural designs using metallic compounds. In this study, we fabricated porous titanium scaffolds (Ti) using SLM and modified the surface of Ti with polydopamine (PDA) and Cu. There are currently no other reported studies with such a combination for osteogenic and angiogenic-related applications. Results showed that such modifications did not affect general appearances and microstructural characteristics of the porous Ti scaffolds. This one-step immersion modification allowed us to modify the surfaces of Ti with different concentrations of Cu ions, thus allowing us to fabricate individualized scaffolds for different clinical scenarios. The modification improved the hydrophilicity and surface roughness of the scaffolds, which in turn led to promote cell behaviors of Wharton's jelly mesenchymal stem cells. Ti itself has high mechanical strength, therefore making it suitable for surgical handling and clinical applications. Furthermore, the scaffolds were able to release ions in a sustained manner which led to an upregulation of osteogenic-related proteins (bone alkaline phosphatase, bone sialoprotein and osteocalcin) and angiogenic-related proteins (vascular endothelial growth factor and angiopoietin-1). By combining additive manufacturing, Ti6Al4V scaffolds, surface modification and Cu ions, the novel hybrid 3D-printed porous scaffold could be fabricated with ease and specifically benefited future bone regeneration in the clinic.