3D-printed Scaffolds Research Articles

The induction of bone formation by 3D-printed PLGA microsphere scaffolds in a calvarial orthotopic mouse model: a pilot study

Polymeric biodegradable microspheres are readily utilized to support targeted drug delivery for various diseases clinically. 3D printed tissue engineering scaffolds from polymer filaments with embedded microspheres or nanoparticles, as well as bulk microsphere scaffolds, have been investigated for regenerative medicine and tissue engineering. However, 3D printed scaffolds consisting only of a homogenous microsphere size with an optimized architecture that includes a unique micro- and macroporosity, have been challenging to produce and hence, have not been assessed in the literature yet. Utilizing our recently established 3D-MultiCompositional Microsphere-Adaptive Printing (3D-McMap) method, the present study evaluated the effectiveness of 3D-printed poly (lactic-co-glycolic acid) (PLGA) microsphere scaffolds, consisting of microsphere sizes 50, 100, or 200 μm, on the induction of bone formation when implanted in the calvarial murine regeneration model. Our results showed that PLGA microsphere scaffolds possess unique properties that support bone regeneration by supporting osteoconduction and stimulating, in our opinion, true spontaneous osteoinduction. The study demonstrated that PLGA microsphere-based scaffolds support bone growth in the absence of additional growth factors and promote osteogenesis primarily via their unique geometric configuration. The larger the microspheres were, the greater de novo bone formation was. This proves that bone tissue engineering scaffolds 3D printed from microspheres, enabled by the 3D-McMap method, are superior over bulk material printed scaffolds, as they possess the unique capability of spontaneous induction of new bone formation. With the addition of encapsulated modulatory bone-forming biomolecules they can substantially improve the spatiotemporal control of tissue morphogenesis, potentially leading to new innovative clinical tissue repair therapies that regenerate bone in large defects correctly and fully.

A promising pullulan/PLA composite: Influence of pullulan in the scaffolds morphology constructed by 3D printing

AbstractManufacturing three‐dimensional scaffolds with significant rough and porous structures is advantageous in tissue regeneration approaches influencing cell growth. Thus, this work aims to study the effect of using different Pullulan contents (PULL) in the poly(lactic) acid (PLA) matrix for 3D printing scaffolds. PLA composites filler with PULL (5 and 10% wt.) were prepared in a thermokinetic mixer, extruded in a machine, and then used to print samples using a fused deposition modeling (FDM) 3D printer. The prepared filaments and scaffolds were characterized using Field emission scanning electron microscopy (FESEM), Fourier‐transform infrared spectroscopy (FTIR), thermogravimetry analyses (TGA), water contact angle (WCA), differential scanning calorimetry (DSC), and hardness techniques. The insertion of PULL into the PLA matrix influenced the increase in diameter and roughness, and density reduction of the composite filaments compared to pristine PLA. Furthermore, the filler promoted an increase in thermal stability, shore hardness, and the development of promising morphological characteristics for cell growth because the walls of the scaffolds are more robust and have more regular‐sized holes. The scaffold fabrication reinforced with 10% PULL presented high surface roughness (up to 1022% if compared with pristine PLA), and open pores can be confirmed successfully compared to pristine PLA. Thus, the use of PULL as a filler in a PLA matrix guarantees the development of composite scaffolds with improved morphological and hardness properties, which could allow the possibility of future research into the application of the proposed material (10% wt. PULL) as an ecologically correct and biocompatible alternative for application in tissue engineering.

Application of electrospinning and 3D-printing based bilayer composite scaffold in the skull base reconstruction during transnasal surgery

Skull base defects are a common complication after transsphenoidal endoscopic surgery, and their commonly used autologous tissue repair has limited clinical outcomes. Tissue-engineered scaffolds prepared by advanced techniques of electrostatic spinning and three-dimensional (3D) printing was an effective way to solve this problem. In this study, soft tissue scaffolds consisting of centripetal nanofiber mats and 3D-printed hard tissue scaffolds consisting of porous structures were prepared, respectively. And the two layers were combined to obtain bilayer composite scaffolds. The physicochemical characterization proved that the nanofiber mat prepared by polylactide-polycaprolactone (PLCL) electrospinning had a uniform centripetal nanofiber structure, and the loaded bFGF growth factor could achieve a slow release for 14 days and exert its bioactivity to promote the proliferation of fibroblasts. The porous scaffolds prepared with polycaprolactone (PCL), and hydroxyapatite (HA) 3D printing have a 300 μm macroporous structure with good biocompatibility. In vivo experiments results demonstrated that the bilayer composite scaffold could promote soft tissue repair of the skull base membrane through the centripetal nanofiber structure and slow-release of bFGF factor. It also played the role of promoting the regeneration of the skull base bone tissue. In addition, the centripetal nanofiber structure also had a promotional effect on the regeneration of skull base bone tissue.

Micro-thin hydrogel coating integrated in 3D printing for spatiotemporal delivery of bioactive small molecules.

Three-dimensional (3D) printing incorporated with controlled delivery is an effective tool for complex tissue regeneration. Here, we explored a new strategy for spatiotemporal delivery of bioactive cues by establishing a precise-controlled micro-thin coating of hydrogel carriers on 3D-printed scaffolds. We optimized the printing parameters for three hydrogel carriers, fibrin cross-linked with genipin (FibGen), methacrylate hyaluronic acid (HAMA), and multidomain peptides (MDP), resulting in homogenous micro-coating on desired locations in 3D printed PCL microfibers at each layer. Using the optimized multi-head printing technique, we successfully established spatial-controlled micro-thin coating of hydrogel layers containing profibrogenic small molecules, Oxo-M and 4-PPBP, and a chondrogenic cue, Kartogenin (KGN). The delivered small molecules showed sustained releases up to 28 days and guided regional differentiation of mesenchymal stem cells (MSCs), thus leading to fibrous and cartilaginous tissue matrix formation at designated scaffold regions in vitro and in vivo. Our micro-coating of hydrogel carriers may serve as an efficient approach to achieve spatiotemporal delivery of various bioactive cues through 3D printed scaffolds for engineering complex tissues.&#xD.

Microstructural and biological characterization of 3D printed PEEK scaffolds coated with alginate/CNT for bone regeneration applications

The main aim of bone tissue engineering is to develop novel scaffold structures that integrate biological functionality with sufficient mechanical strength and properties. In this study, bone scaffolds were fabricated using polyether ether ketone (PEEK) via 3D printing, resulting in three different porous designs. To enhance their biological attributes, these scaffolds were coated with an alginate and carbon nanotube (CNT) composite using a freeze-drying technique. The biological characteristics of fabricated samples, such as biocompatibility and bioactivity, were evaluated in simulated body fluid (SBF). Field emission scanning electron microscopy (FE-SEM) analysis showed that the 3D-printed PEEK scaffolds had a porous, uniform, and interconnected architecture with pore sizes between 321–378 µm. Energy-dispersive X-ray spectroscopy (EDS) and X-ray diffraction (XRD) confirmed the formation of hydroxyapatite (HA) and bioactive calcium phosphate (Ca-P) on the scaffold surfaces, indicating their bioactivity. Cell biocompatibility was assessed using the MTT assay, which revealed a high cell viability rate of approximately 97% and no significant toxicity. Consequently, the 3D-printed PEEK scaffold coated with Alginate/0.3%wt CNT demonstrated promising microstructure, bioactivity, and biocompatibility, making it suitable for bone tissue regeneration.Graphical abstract

3D-printed magnesium-doped micro-nano bioactive glass composite scaffolds repair critical bone defects by promoting osteogenesis, angiogenesis, and immunomodulation

Magnesium ions play an important immune-regulatory role during bone repair. For this study, we prepared micro-nano bioactive glass (MNBG) containing magnesium, which can release magnesium, silicon, and calcium ions and has a positive impact on osteogenic differentiation and vascular regeneration. In this study, MgMNBG was compounded and combined with poly(lactic-co-glycolic acid (PLGA) and polycaprolactone (PCL) for 3D printing. Afterwards, the physicochemical properties and bone repair performance of the scaffolds were evaluated throughin vitroandin vivoexperiments. We also investigated the effects of MgMNBG on osteogenic differentiation, immune regulation, and vascular regeneration. The results showed that MgMNBG can inhibit inflammation and promote osteogenesis and angiogenesis by regulating macrophages. PLGA/PCL/MgMNBG scaffolds have good osteogenic and angiogenic effects, and the composite scaffolds have excellent bone repair performance and potential application value.

3D-Printed hydrogel scaffolds with drug- and stem cell-laden core/shell filaments for cancer therapy and soft tissue repair.

Treatment of local tumor recurrence and repair of the tissue defects after tumorectomy still remain clinical challenges. Currently, controlled release of therapeutic drugs is one of the widely used approaches to kill the residual and recurrent cancer cells, and stem cell-laden hydrogel scaffolds are promising candidates for soft tissue repair. However, hydrogel scaffolds with the bifunction of controlled release of therapeutic drugs for cancer therapy and loading stem cells for tissue repair are still not well established. In this study, we fabricated a biphasic hydrogel scaffold containing two types of core/shell filaments with drugs and stem cells loaded in the core part of these two filaments. Black phosphorus nanosheets were added to alginate (the shell layer) in the drug-loaded filament, endowing the scaffold with a photothermal effect under near infrared (NIR) laser irradiation. Moreover, NIR could trigger the drug release from the core/shell filaments to achieve photothermal-chemotherapy of cancer. Additionally, stem cells embedded in the core parts of the other filaments could maintain high cell viability due to the protection of the shell layer (pure alginate), which promoted soft tissue regeneration in vivo. Thus, the prepared biphasic scaffold with drug- and stem cell-laden core/shell filaments may be a potential candidate to fill the tissue defects after the surgical resection of tumors to kill the residual and recurrent cancer and repair the tissue defects.

Osteochondral Regeneration With Anatomical Scaffold 3D-Printing-Design Considerations for Interface Integration.

There is a clinical need for osteochondral scaffolds with complex geometries for restoring articulating joint surfaces. To address that need, 3D-printing has enabled scaffolds to be created with anatomically shaped geometries and interconnected internal architectures, going beyond simple plug-shaped scaffolds that are limited to small, cylindrical, focal defects. A key challenge for restoring articulating joint surfaces with 3D-printed constructs is the mechanical loading environment, particularly to withstand delamination or mechanical failure. Although the mechanical performance of interfacial scaffolds is essential, interface strength testing has rarely been emphasized in prior studies with stratified scaffolds. In the pioneering studies where interface strength was assessed, varying methods were employed, which has made direct comparisons difficult. Therefore, the current review focused on 3D-printed scaffolds for osteochondral applications with an emphasis on interface integration and biomechanical evaluation. This 3D-printing focus included both multiphasic cylindrical scaffolds and anatomically shaped scaffolds. Combinations of different 3D-printing methods (e.g., fused deposition modeling, stereolithography, bioprinting with pneumatic extrusion of cell-laden hydrogels) have been employed in a handful of studies to integrate osteoinductive and chondroinductive regions into a single scaffold. Most 3D-printed multiphasic structures utilized either an interdigitating or a mechanical interlocking design to strengthen the construct interface and to prevent delamination during function. The most effective approach to combine phases may be to infill a robust 3D-printed osteal polymer with an interlocking chondral phase hydrogel. Mechanical interlocking is therefore recommended for scaling up multiphasic scaffold applications to larger anatomically shaped joint surface regeneration. For the evaluation of layer integration, the interface shear test is recommended to avoid artifacts or variability that may be associated with alternative approaches that require adhesives or mechanical grips. The 3D-printing literature with interfacial scaffolds provides a compelling foundation for continued work toward successful regeneration of injured or diseased osteochondral tissues in load-bearing joints such as the knee, hip, or temporomandibular joint.

Topology-defined bioactive properties of porous Ti-6Al-4V scaffolds produced by laser powder bed fusion

The effect of the design of additively printed Ti porous structures on their bioactive properties is elucidated by in vitro testing. 3D-printed scaffolds with pores defined by several bioinspired triply periodic minimal surfaces as well as by a strut model have been engineered. Cell proliferation, angiogenesis and osteogenesis have been studied with the help of multipotent mesenchymal stromal cells. The elementary unit size and pore design can notably modify bioactive properties of porous structures. The models providing maximal bioactive activity of developed scaffolds are discussed.

A modular approach to 3D-printed bilayer composite scaffolds for osteochondral tissue engineering

Prolonged osteochondral tissue engineering damage can result in osteoarthritis and decreased quality of life. Multiphasic scaffolds, where different layers model different microenvironments, are a promising treatment approach, yet stable joining between layers during fabrication remains challenging. To overcome this problem, in this study, a bilayer scaffold for osteochondral tissue regeneration was fabricated using 3D printing technology which containing a layer of PCL/hydroxyapatite (HA) nanoparticles and another layer of PCL/gelatin with various concentrations of fibrin (10, 20 and 30 wt.%). These printed scaffolds were evaluated with SEM (Scanning Electron Microscopy), FTIR (Fourier Transform Infrared Spectroscopy) and mechanical properties. The results showed that the porous scaffolds fabricated with pore size of 210–255 µm. Following, the ductility increased with the further addition of fibrin in bilayer composites which showed these composites scaffolds are suitable for the cartilage part of osteochondral. Also, the contact angle results demonstrated the incorporation of fibrin in bilayer scaffolds based on PCL matrix, can lead to a decrease in contact angle and result in the improvement of hydrophilicity that confirmed by increasing the degradation rate of scaffolds containing further fibrin percentage. The bioactivity study of bilayer scaffolds indicated that both fibrin and hydroxyapatite can significantly improve the cell attachment on fabricated scaffolds. The MTT assay, DAPI and Alizarin red tests of bilayer composite scaffolds showed that samples containing 30% fibrin have the more biocompatibility than that of samples with 10 and 20% fibrin which indicated the potential of this bilayer scaffold for osteochondral tissue regeneration.Graphical

Methods to Enhance Mechanical Strength of 3D Printed Chitosan Scaffolds for Jawbone Regeneration

Current jaw reconstruction methods using autografts and allografts have limitations such as donor site morbidity, limited bone volume, and immunological rejection. As opposed to surgical methods synthetic biomaterials are used however they often fall short in providing the optimal combination of biocompatibility, mechanical strength, and customizable design required for effective jawbone reconstruction. 3D-printed chitosan scaffolds offer a promising alternative due to their biocompatibility, ease of customization, and potential for improved mechanical strength. This review explores strategies to optimize 3D-printed chitosan scaffolds for jaw reconstruction. We examine ways to increase their mechanical strength without compromising biocompatibility, with a particular emphasis on chemical modifications such as hydroxyapatite (HA) and beta-tricalcium phosphate (β-TCP) cross-linking and chitosan polyelectrolyte complex formation. We also discuss the critical roles that 3D printing processes (FDM and SLA) and intrinsic chitosan qualities (degree of deacetylation) play in making an ink printable. Optimizing 3D printing methods for chitosan-ceramic composites and exploring biocompatible additives to enhance printability are identified as key areas for further research. By addressing these challenges, 3D-printed chitosan scaffolds have the potential to become next-generation biomaterials for jaw reconstruction, revolutionizing the field through precise anatomical adaptation, enhanced osteoconductivity, controlled biodegradation, and the capacity for incorporating bioactive molecules, ultimately leading to accelerated bone regeneration and improved functional and aesthetic outcomes.

Mechanical deviation in 3D-Printed PLA bone scaffolds during biodegradation

Large or carcinogenic bone defects may require a challenging bone tissue scaffold design ensuring a proper mechanobiological setting. Porosity and biodegradation rate are the key parameters controlling the bone-remodeling process. PLA presents a great potential for geometrically flexible 3-D scaffold design. This study aims to investigate the mechanical variation throughout the biodegradation process for lattice-type PLA scaffolds using both experimental observations and simulations. Three different unit-cell geometries are used for creating the scaffolds: basic cube (BC), body-centered structure (BCS), and body-centered cube (BCC). Three different porosity ratios, 50 %, 62.5 %, and 75 %, are assigned to all three structures by altering their strut dimensions. 3-D printed scaffolds are soaked in PBS solution at 37 °C for 15, 30, 60, 90, and 120 days both unloaded and under dead load. Water absorption, weight loss, and compression stiffness are measured to characterize the first-stage degradation and investigate the possible influences of these parameters on the whole biodegradation process. The strength reduction stage of biodegradation is simulated by solving pseudo-first-order kinetics-based molecular weight change equation using FEA with equisized cubic (voxel-like) elements.For the first stage, mechanical load does not have a statistically significant effect on biodegradation. BCC with 62.5 % porosity shows a maximum water absorption rate of around 25 % by the 60th day which brings an advantage in creating an aquatic environment for cell growth. Results indicate a significant water deposition inside almost all scaffolds and water content is determined to be the main reason for the retained or increased compression stiffness. A distinguishable stiffness increase in the initial degradation process occurs for 75 % porous BC and 50 % porous BCC scaffolds. Following the quasi-stable stage of biodegradation, almost all scaffolds lost their rigidity by around 44–48 % within 120 days based on numerical results. Therefore, initial stiffness increase in the quasi-stable stage of biodegradation can be advantageous and BCC geometry with a porosity between 50% and 62 % is the optimum solution for the whole biodegradation process.

Sustained BMP-2 delivery via alginate microbeads and polydopamine-coated 3D-Printed PCL/β-TCP scaffold enhances bone regeneration in long bone segmental defects

Background/ObjectiveRepair of long bone defects remains a major challenge in clinical practice, necessitating the use of bone grafts, growth factors, and mechanical stability. Hence, a combination therapy involving a 3D-printed polycaprolactone (PCL)/β-tricalcium phosphate (β-TCP) scaffold coated with polydopamine (PDA) and alginate microbeads (AM) for sustained delivery of bone morphogenetic protein-2 (BMP-2) was investigated to treat long bone segmental defects. MethodsSeveral in vitro analyses were performed to evaluate the scaffold osteogenic effects in vitro such as PDA surface modification, namely, hydrophilicity and cell adhesion; cytotoxicity and BMP-2 release kinetics using CCK-8 assay and ELISA, respectively; osteogenic differentiation in canine adipose-derived mesenchymal stem cells (Ad-MSCs); formation of mineralized nodules using ALP staining and ARS staining; and mRNA expression of osteogenic differentiation markers using RT-qPCR. Bone regeneration in femoral bone defects was evaluated in vivo using a rabbit femoral segmental bone defect model by performing radiography, micro-computed tomography, and histological observation (hematoxylin and eosin and Masson's trichrome staining). ResultsThe PDA-coated 3D-printed scaffold demonstrated increased hydrophilicity, cell adhesion, and cell proliferation compared with that of the control. BMP-2 release kinetics assessment showed that BMP-2 AM showed a reduced initial burst and continuous release for 28 days. In vitro co-culture with canine Ad-MSCs showed an increase in mineralization and mRNA expression of osteogenic markers in the BMP-2 AM group compared with that of the BMP-2-adsorbed scaffold group. In vivo bone regeneration evaluation 12 weeks after surgery showed that the BMP-2 AM/PDA group exhibited the highest bone volume in the scaffold, followed by the BMP-2/PDA group. High cortical bone connectivity was observed in the PDA-coated scaffold groups. ConclusionThese findings suggest that the combined use of PDA-coated 3D-printed bone scaffolds and BMP-2 AM can successfully induce bone regeneration even in load-bearing bone segmental defects. The translational potential of this articleA 3D-printed PCL/β-TCP scaffold was fabricated to mimic the cortical bone of the femur. Along with the application of PDA surface modification and sustained BMP-2 release via AM, the developed scaffold could provide suitable osteoconduction, osteoinduction, and osteogenesis in both in vitro settings and in vivo rabbit femoral segmental bone defect models. Therefore, our findings suggest a promising therapeutic option for treating challenging long bone segmental defects, with potential for future clinical application.

Osteogenic citric acid linked chitosan coating of 3D-printed PLA scaffolds for preventing implant-associated infections

>25 % of the patients who receive orthopedic implants have been reported with implant-associated osteomyelitis, which can result in inflammation, osteolysis, and aseptic loosening of implants. Current treatment methods doesn't ensure defect healing and prevention from reinfection. Thermoplastic-based 3D-printed scaffolds offer a bioresorbable, biocompatible, and mechanical strong implant system. However, the hydrophobicity and bio-inertness of these polymers prevent their use in clinics. In this study, we developed dual functionalized scaffolds with osteogenic and antibacterial properties by immobilizing citric acid-linked chitosan on oxygen plasma etched 3D-printed PLA scaffolds through an EDC-NHS coupling reaction. Acellular mineralization of these scaffolds in DMEM demonstrated the deposition of crystalline hydroxyapatite. In addition, the antibacterial properties of these surface-modified scaffolds have been determined against E. coli and S. aureus, where the citric-linked chitosan biofunctionalized 3D-printed PLA scaffolds showed significantly higher antibacterial activity in comparison to oxygen-etched PLA and PLA scaffolds due to the synergistic effect of citric acid and chitosan functionalities. MG-63 cells exhibited increased proliferation and osteogenic activity on the modified scaffolds compared to the PLA and OP-PLA. These 3D-printed scaffolds, coated with citric-linked chitosan, can be a potential solution to orthopedic complications such as critical-sized bone defects and implant-associated osteomyelitis.

3D-printed biomimetic bone scaffold loaded with lyophilized concentrated growth factors promotes bone defect repair by regulation the VEGFR2/PI3K/AKT signaling pathway

This study investigates the effects of concentrated growth factors (CGF) and bone substitutes on the proliferation and differentiation of bone marrow mesenchymal stem cells (BMSCs), as well as the development of a novel 3D-printed biomimetic bone scaffold. Based on the structure of cancellous bone, 3D-printed bionic bone with sustainable release of growth factors and Ca2+ was prepared. Using BMSCs and EA.hy926 in co-culture with the bionic bone scaffold, experimental results demonstrate that this bionic structural design enhances cell proliferation and adhesion, and that the bionic bone possesses the ability to promote bone and vascular regeneration directly. Transcriptomics, western blot analysis, and flow cytometry are employed to investigate the effects of CGF and Ca2+ on the signaling pathways of BMSCs. The study reports that vascular endothelial growth factor (VEGF) released by CGF activated VEGFR2 on BMSCs, leading to Ca2+ influx and activation of the PI3K/AKT signaling pathway, thereby influencing osteogenesis. Animal experiments confirm the ability of the bionic bone to promote osteogenesis in vivo, and its unique degradation pattern accelerates the in vivo repair of bone defects. In conclusion, this study presents a novel biomimetic strategy and, for the first time, explores the potential mechanism by which VEGF and Ca2+ regulate BMSCs differentiation through the VEGFR2/PI3K/AKT signaling pathway. These insights offer a new perspective for the development of innovative bone substitute materials.

3D printing incorporating gold nanozymes with mesenchymal stem cell-derived hepatic spheroids for acute liver failure treatment

Acute liver failure (ALF) is a highly fatal disease, necessitating the advancement and optimization of alternative therapeutic strategies to benefit patients awaiting liver transplantation. In this study, we innovatively established the antioxidant nanozyme-hepatocyte-like cells (HLCs) microtissue sheets (HS/N–Au@composite) for ALF therapy. We first prepared a 3D-printed hyaluronic acid/gelatin/sodium alginate scaffold with N-acetylcysteine (NAC)-capped gold nanoclusters (NAC-Au NCs), forming the N–Au@hydrogel. For the encapsulation of HLC spheroids, we used a biocompatible hybrid hydrogel composed of decellularized extracellular matrix (dECM), thrombin, and fibrinogen, resulting in the HS@dECM hydrogel. Utilizing 3D printing technology, we integrated the N–Au@hydrogel with the HS@dECM hydrogel to create the HS/N–Au@composite for in situ transplantation to treat ALF. Our results demonstrated that NAC-Au NCs effectively mitigated reactive oxygen species (ROS)-induced liver necrosis in ALF. Additionally, the N–Au@hydrogel provided mechanical support, ensuring the proper landing and effective functioning of the transplanted HLC spheroids. The HS/N–Au@composite synergistically decreased serum transaminase levels, reduced the accumulation of pro-inflammatory cytokines, accelerated liver function recovery, and promoted liver regeneration in ALF treatment. This combination of HLC spheroids and NAC-Au NCs nanozymes via 3D-printed composite scaffolds represents a promising strategy for enhancing hepatocyte transplantation and advancing stem cell regenerative medicine in ALF therapy.

3D-Printed Carbon Scaffold for Structural Lithium Metal Batteries.

Focus on advancement of energy storage has now turned to curbing carbon emissions in the transportation sector by adopting electric vehicles (EVs). Technological advancements in lithium-ion batteries (LIBs), valued for their lightweight and high capacity, are critical to making this switch a reality. Integrating structurally enhanced LIBs directly into vehicular design tackles two EV limitations: vehicle range and weight. In this study, 3D-carbon (3D-C) lattices, prepared with an inexpensive stereolithography-type 3D printer followed by carbonization, are proposed as scaffolds for Li metal anodes for structural LIBs. Mechanical stability tests revealed that the 3D-C lattice can withstand a maximum stress of 5.15 ± 0.15MPa, which makes 3D-C lattices an ideal candidate for structural battery electrodes. Symmetric cell tests show the superior cycling stability of 3D-C scaffolds compared to conventional bare Cu foil current collectors. When 3D-C scaffolds are used, a small overpotential (≈0.075V) is retained over 100 cycles at 1mA cm-2 for 3 mAh cm-2, while the overpotential of a bare Cu symmetric cell is unstable and increased to 0.74V at the 96th cycle. The precisely oriented internal pores of the 3D-C lattice confine lithium metal deposits within the 3D scaffold, effectively preventing short circuits.

Cleaning strategies for 3D-printed porous scaffolds used for bone regeneration fabricated via ceramic vat photopolymerization

Vat photopolymerization has gained prominence in bone tissue engineering owing to its capability to fabricate intricate structures that closely mimic the natural bone tissue. Thorough cleaning of uncured ceramic slurry from the as-printed structures is essential, as the presence of residue within the structure can obstruct pores during sintering. Given the limitations of conventional spray cleaning for these structures, this study seeks to investigate alternative cleaning approaches. Specifically, the efficacy of dibasic ester (DBE) and LithaSol 80, coupled with ultrasonic and soaking methods, is examined to identify optimal strategies for the thorough removal of viscous residual slurry (LithaBone HA 480). To examine the effect of temperature on cleaning ability, printed scaffolds were soaked in the cleaning solutions at 23, 30, 40, and 50 °C for 24 h. Based on the results, 50 °C was chosen as the temperature for further analysis while using both soaking (24, 48, 72 and 96 h) and ultrasonic (5, 15 and 30 min; 1, 2, 3, and 4 h) as the cleaning methods. The cross-sectional image of the scaffolds showed that at least 48 h and 30 min is required for effective cleaning with soaking and ultrasonic, respectively. Microstructure analysis of scaffolds cleaned with LithaSol 80 revealed smoother surfaces, while scaffolds treated with DBE showed visibly contracted pores with peeling effect suggesting that DBE exerts a more aggressive action on the cured slurry in contrast to LithaSol 80. Notably, significant difference in mass loss was observed between scaffolds treated with LithaSol 80 and DBE. The significantly higher mass loss observed with DBE suggests that it not only impacts uncured slurry but also possibly affects cured slurry. Accordingly, the results indicate that DBE is notably more effective in cleaning; however, LithaSol 80 is more appropriate for maintaining structural integrity combined with soaking cleaning method. No significant difference was observed in compressive strength between most sintered scaffolds.

Effects of Ultrasonic Vibration on 3D Printing of Polylactic Acid/Akermanite Nanocomposite Scaffolds

The mechanical properties of 3D-printed scaffolds for load-bearing implantation are crucial. Although the addition of nanoparticles to polymeric matrix scaffolds can improve their mechanical and biological properties, due to certain limitations in printability, high amounts of reinforcement cannot be used. Therefore, in this study, an attempt was made to use ultrasonic (UT) vibration to inhibit nozzle clogging during fused filament fabrication (FFF) of polylactic acid (PLA) scaffolds including 0, 20, and 40 wt.% Akermanite (Ak). Nozzle clogging happened during the conventional 3D printing of PLA-40wt.%Ak, while that did not occur during UT-assisted 3D printing of PLA-40wt.%Ak. Results of X-ray Diffraction (XRD) analysis and Scanning Electron Microscopy (SEM) indicated that applying ultrasonic (UT) vibration had no negative effect on the phases and morphology of the scaffolds. The results obtained by the compression test indicated that applying UT during 3D-printing resulted in almost 27% increment of elastic modulus and almost 25% increase of the compressive strength of the scaffolds. As the conclusion, this study highlights the effectiveness of ultrasonic-assisted 3D printing in producing nanocomposite scaffolds with significantly higher nanoparticle loadings, as compared to conventional printing methods. By utilizing ultrasonic vibration during the printing process, the study showcases the possibility of overcoming viscosity limitations and optimizing the mechanical performance of scaffolds for various biomedical applications, including bone tissue engineering.

Evaluating the efficacy of uniformly designed square mesh resin 3D printed scaffolds in directing the orientation of electrospun PCL nanofibers

Replicating the architecture of extracellular matrices (ECM) is crucial in tissue engineering to support tissues’ natural structure and functionality. The ECM’s structure plays a significant role in directing cell alignment. Electrospinning is an effective technique for fabricating nanofibrous substrates that mimic the architecture of extracellular matrices (ECM). This study aims to evaluate the efficacy of resin 3D-printed scaffolds made from a low-conductivity material (i.e., a resin composed of methacrylated oligomers, monomers, and photoinitiators) in directing the alignment of electrospun polycaprolactone (PCL) nanofibers. Six 3D-printed scaffolds were fabricated using stereolithography (SLA) technology and strategically positioned on an aluminum foil collector plate during electrospinning. The structured geometry of the scaffolds, rather than the local electric field distribution, is hypothesized to guide nanofiber alignment. Images acquired through the scanning electron microscopy (SEM) were used to analyze and statistically quantify the nanofibrous scaffolds to evaluate the alignment of nanofibers over the scaffolds compared to a set of randomly deposited control nanofiber samples in the absence of the 3D printed scaffolds. SEM images also showed significant alignment of nanofibers within the pores of scaffolds, using histograms as a means for indicating the distribution of orientation angles. Statistical analysis revealed that this distribution deviates from normality due to the deviations in the tails and the existence of relatively smaller peaks at angles relative to 0°, particularly within a range of ± 50° and ± 40°. It is further found that the average peak orientation angle relative to 0° had a maximum probability of 0.014. Furthermore, the statistical analysis confirmed the distribution and significant differences in orientation between test samples with 3D-printed scaffolds and control samples. These findings demonstrate the effectiveness of resin 3D-printed scaffolds, particularly their geometric filtering effect, leading to controlled nanofiber alignment, which is proposed to be beneficial for enhancing cell adhesion, proliferation, and cell migration in tissue engineering applications.