The tendon/ligament–bone (T/L–B) interface represents a critical junction where tendons and ligaments anchor to bone and is characterized by a complex, graded structure. Pathological conditions caused by aging, lifestyle factors, or trauma can severely impair this interface, leading to functional deficits and a significant decline in quality of life. However, replicating the intricate structural and biological features of the native T/L–B interface remains a major challenge with conventional fabrication methods. In this context, three-dimensional (3D) bioprinting has emerged as a promising approach for tissue repair and regeneration. This review aims to summarize the application of 3D bioprinting technologies in the reconstruction of the T/L–B interface. The review first provides a brief overview of the biology of the T/L–B interface. It then examines recent innovations in 3D printing technologies, biomaterials, and gradient structure design applied to interface regeneration. The review also explores strategies for optimizing the mechanical performance and bioactivity of 3D-bioprinted scaffolds for T/L–B interface regeneration. Finally, it highlights current challenges and future directions for advancing 3D bioprinting in this field. This review provides new insights into the clinical translation of 3D-bioprinted T/L–B interface constructs and may inform the future development of next-generation orthopedic implants.  

Three-dimensional bioprinting has emerged as a transformative biofabrication technology capable of engineering complex tissue constructs for regenerative medicine. While considerable progress has been made in replicating soft tissues using hydrogel-based bioprinting, the fabrication of mechanically robust bone-mimicking constructs remains a significant challenge. The mechanical heterogeneity of bone, including its anisotropic structure, varying mineral density, and intricate extracellular matrix composition, complicates the development of bioinks that can simultaneously achieve printability, structural integrity, and cellular viability. Recent advancements have focused on optimizing the mechanical properties of bioinks through composite hydrogels, osteoinductive nanomaterials, and bioactive moieties that enhance cell adhesion and differentiation. This review examines the role of mechanical cues in directing mesenchymal stem cell fate, the interplay between material stiffness and osteogenesis, and strategies to enhance bioink performance. We highlight limitations in mechanical compliance and propose novel biomaterial designs, crosslinking strategies, and scaffold functionalization to overcome these barriers. This review aims to bridge the gap between biomaterials science and clinical translation, with the ultimate goal of advancing functional bone graft substitutes.

Drug administration involves the precise delivery of therapeutic agents to targeted sites in a controlled manner, maximizing efficacy while minimizing adverse effects. This goal is pursued through drug delivery systems (DDSs), built from synthetic, natural, or hybrid biomaterials, that encapsulate and release drugs via diverse administration routes and mechanisms. Their core purpose is to localize pharmacological activity, reduce systemic toxicity, and protect surrounding healthy tissues. Despite advances, persistent challenges remain, including poor bioavailability, instability in drug loading and release profiles, limited targeting accuracy, undesirable systemic persistence, and inadequate spatiotemporal control. Additional concerns include inadequate chemical stability, patient compliance, and risks of long-term toxicity, all of which hinder clinical translation. To overcome these obstacles, metamaterials—engineered structures with geometry-driven properties—have emerged as promising platforms. By leveraging additive manufacturing and nanoscale design, metamaterials offer tunable architectures and unconventional physicochemical properties, enabling precise control over release dynamics, spatial specificity, and therapeutic outcomes. This review highlights the integration of metamaterials into DDSs, focusing on material selection, structural design strategies, fabrication challenges, and the novel possibilities enabled by three-dimensional printing. We also examine their applications in sustained, pulsatile, and stimuli-responsive release, targeted therapy, theranostics, and regenerative medicine. Finally, we discuss unresolved issues such as biocompatibility, scalability, and translational barriers, emphasizing the transformative potential of metamaterial-enabled DDSs in advancing precision medicine and healthcare innovation.

The precise spatial patterning of living cells represents a foundational capability in bio-systems engineering, enabling the systematic study of collective cellular behaviors and the fabrication of increasingly complex functional tissues. Conventional methods for achieving this control, while numerous, are often constrained by static pattern formation, the need for biochemical labels that can alter cell function, or requirements for non-physiological media. In this context, acoustic-field-based manipulation has emerged as a uniquely powerful and biocompatible alternative. This review synthesizes these advancements under the unifying concept of “acoustic lithography,” a framework that captures the technology’s capacity for rapid, parallel, and label-free cellular organization. The discussion covers the core physical principles of acoustic radiation force and acoustic streaming before surveying the diverse technological landscape, from bulk and surface acoustic waves to advanced acoustic holography. It further highlights the impact of these tools across a spectrum of applications, including high-throughput analysis, biomimetic co-culture engineering, advanced biofabrication, and clinical sorting. Collectively, these applications demonstrate the field’s trajectory as it moves beyond static patterning to encompass the integrated control of structure, environment, and function. Viewing the technology through this broader engineering lens underscores its significance as a vital platform, charting a course for the next generation of dynamically engineered living systems.

Osteochondral defects, which involve injury to both the articular cartilage and the underlying subchondral bone, present a considerable therapeutic challenge due to cartilage’s poor intrinsic capacity for regeneration and the intricate, gradient structure of the osteochondral junction. Tissue engineering offers a promising strategy for regenerating this biphasic tissue. Chitosan has attracted significant research interest due to its favorable biocompatibility, controlled degradability, natural antibacterial activity, and structural resemblance to endogenous glycosaminoglycans. Integrating chitosan with 3D printing allows the production of scaffolds with customizable structures, porosity, and mechanical properties tailored to patient needs. Moreover, chitosan can easily be blended with various natural polymers to develop composite bioinks that improve osteogenic and chondrogenic potential, thereby enhancing the functional performance of scaffolds. This review examines research literature spanning January 2020 to October 2025. Recent advances include the development of functionalized chitosan derivatives for improved printability and crosslinking, as well as the incorporation of cells and growth factors to create bioactive, cell-laden constructs. This review provides an extensive overview of the physicochemical and biological characteristics of chitosan pertinent to osteochondral regeneration, discusses diverse 3D printing strategies utilized to construct chitosan-based composite scaffolds, and emphasizes their demonstrated potential in improving cellular responses, stimulating bone and cartilage formation, supporting biomineralization, and achieving controlled delivery of bioactive agents. Finally, we discuss current challenges, such as optimizing scaffold degradation kinetics and vascularization, and future perspectives on the clinical translation of these innovative constructs for effective osteochondral regeneration.

The integration of artificial intelligence (AI)-enabled multimodal computed tomography (CT)/magnetic resonance imaging (MRI) medical imaging and three-dimensional (3D) printing technology represents a pivotal direction in medical engineering for advancing precision diagnosis and therapy. Multimodal data fusion serves as the primary strategy to enhance the accuracy of 3D-printed models; however, cross-modal data fusion is hindered by inherent technical challenges, including failures in feature alignment and discrepancies in the physical properties of imaging datasets. In recent years, the advancement and seamless integration of AI technology have emerged as the core link bridging the entire workflow, from multimodal CT/MRI imaging acquisition to 3D printing, offering novel paradigms for the development of high-precision 3D printing technology in clinical settings. This review systematically elaborates on AI’s core technical underpinnings for multimodal imaging and 3D printing: AI effectively mitigates integration and adaptation hurdles arising from intrinsic discrepancies in data source characteristics through three key pathways—artifact reduction and optimization of raw imaging data, precise cross-modal registration, and fine-grained segmentation of anatomical structures. Furthermore, AI-driven optimization of 3D rendering effects, combined with four-view projection, significantly enhances the fidelity of anatomical detail reproduction, thereby minimizing the matching error between 3D-printed models and in vivo physical entities. Subsequently, the review details the clinical application value of multimodal 3D printing technology across key medical specialties, including orthopedics, oncological surgery, dentistry, and vascular surgery, while concomitantly highlighting prevailing challenges in technical translation and clinical adoption. Finally, it outlines future development directions from three critical dimensions: technological synergy (among AI, imaging, and 3D printing), material advancement (targeting durability and functional adaptability), and application expansion (to underserved clinical scenarios such as rehabilitation). This work aims to provide a comprehensive reference for accelerating the clinical translation of this interdisciplinary technology.  

Hydrogel materials and scaffolds have emerged as transformative tools in biological research by offering precise control over cell viability, metabolism, and productivity. Their compatibility with three-dimensional (3D) bioprinting and patterning technologies enables the precise and reproducible organization of living components, facilitating novel experimental paradigms across diverse disciplines. Although most 3D hydrogel research has emphasized mammalian cell applications, particularly in tissue engineering, there is a growing body of research applying these technologies to study, manipulate, and harness a variety of microorganisms, such as bacteria. This review explores the latest advances in microbial hydrogel encapsulation, focusing on material selection and patterning methods designed to preserve microbial viability and function. We compare the distinct requirements and challenges of culturing microorganisms in hydrogels versus mammalian systems and highlight recent breakthroughs in bacterial bioprinting that are advancing microbiological research, paving the way for current and emerging applications in various areas, including oral health. By synthesizing current knowledge and identifying promising future directions, this review underscores the potential of microbial hydrogel culture as a versatile platform for investigating microbial communities, probing bacterial– material interactions, and engineering living materials with applications in human health and environmental systems.

Tissue loss, fibrosis-prone repair, and immune-mediated graft failure remain persistent obstacles in regenerative medicine. Within this context, 3D bioprinting is shifting from structure-centric fabrication to a platform for programmed immune modulation. This review synthesizes evidence across materials, architecture, and living components to delineate how bioprinted constructs can steer host responses toward resolution and durable function. We first examine events at the blood–biomaterial interface, including protein corona formation, complement–coagulation crosstalk, and leukocyte recruitment, and map them to tunable parameters, such as chemistry, stiffness, degradability, topography, and pore geometry that direct macrophage and dendritic-cell programs. We compare natural and synthetic bioinks, emphasizing printability windows, batch control, and impurity management as prerequisites for interpretable immunological readouts. We survey stimuli-responsive inks triggered by pH, reactive oxygen species, enzymes, light, or magnetic fields to deliver cytokines, chemokines, and metabolites with temporal precision, and highlight architected lattices and gradients that guide cell trafficking, vascular and lymphatic integration, and mechano-immune conditioning. Cell- and signal-centric strategies include immune–stromal coprinting, extracellular vesicle embedding, membrane cloaking for immune stealth or targeting, and synthetic circuits that sense inflammation and secrete immunoregulatory payloads. Finally, we identify translational bottlenecks and outline opportunities in 4D bioprinting, AI-assisted design, digital twins, and in situ printing. Treating immunity as a primary design variable is essential for predictable, durable, and clinically credible bioprinted therapies.  

Traditional cancer research models face inherent limitations, as two-dimensional cell cultures fail to capture the complexity of tumor biology, while animal models are confounded by species-specific discrepancies. The integration of tumor organoids with three-dimensional (3D) bioprinting has recently emerged as a transformative strategy. This approach combines the histological and genetic fidelity of organoids with the spatial precision and structural controllability of 3D bioprinting, thereby enabling the fabrication of biomimetic tumor models. Such models more faithfully recapitulate critical features of the tumor microenvironment (TME), addressing major gaps in conventional experimental systems. This review systematically examines the principles, recent advances, and translational applications of 3D bioprinting-enabled tumor organoids, including the biological basis of organoids, key bioprinting strategies, and technical considerations. Major applications include constructing heterogeneous TMEs with immune interactions, engineering vascularized tumor structures, enabling high-throughput drug screening, validating bioprinted organoids using clinical samples, and advancing clinical translation, regulatory frameworks, and Good Manufacturing Practice-compliant manufacturing of tumor organoids. Despite substantial progress, several challenges remain, including limited printing resolution, bioink instability, difficulties in sustaining long-term cultures, and gaps in standardization. Nevertheless, integration with emerging technologies, such as microfluidics, artificial intelligence, big data analytics, and standardized biomanufacturing platforms, is anticipated to bridge the gap between basic tumor research and clinical translation. Ultimately, these synergistic advances may accelerate the development of personalized cancer therapies and improve patient outcomes.

Tissue development and regeneration arise from a dynamic interplay among cells, the extracellular matrix (ECM), and surrounding biophysical and biochemical cues. These interactions form the basis for stimuli-responsive materials for advanced regenerative technologies (SMART) that drive innovation in four-dimensional (4D) bioprinting for tissue engineering. This review discusses the biophysical foundations of SMART materials, emphasizing native ECM components, their interactions, and organ-specific properties that inform biomimetic material design. We highlight recent advances in 4D SMART systems, including ionic self-healing, pH-, thermal-, hydration-, and magneto-responsive materials, and their roles in mimicking developmental and regenerative processes. This is followed by a comparative overview of these stimuli-responsive material classes, benchmarked against one another, native ECM performance, and clinical translation requirements, revealing persistent gaps in long-term stability, multi-stimuli integration, and regulatory feasibility. Together, these insights provide an interdisciplinary framework for designing adaptive, responsive biomaterials that guide tissue morphogenesis and advance the future of regenerative medicine.

Tracheal reconstruction remains a major clinical challenge due to persistent limitations in graft vascularization, epithelialization, and long-term mechanical compatibility. Conventional synthetic scaffolds and autologous grafts often fail to achieve durable integration, underscoring the need for innovative biofabrication strategies. In the present study, we elucidate the mechanoregulatory role of the long non-coding (lnc) RNA Pvt1 in controlling endothelial cell proliferation and focal adhesion dynamics during tracheal regeneration. Patient-specific tracheal stents were fabricated using extrusion-based three-dimensional bioprinting with hierarchically optimized architectures that combined polycaprolactone (PCL) copolymers with endothelial progenitor cell (EPC)-recruiting motifs. Computational fluid dynamics-guided nozzle path planning and in situ piezoelectric characterization enabled sub- 200 μm resolution in replicating native tracheal microtopography while maintaining 94% EPC viability after printing. Pvt1-enriched bioinks significantly enhanced vascularization, yielding a 2.3-fold increase in neovascularization compared with controls in rat tracheal defect models, alongside a 38% reduction in fibrotic markers. The constructs exhibited a dual-stage biodegradation profile (30% mass loss at eight weeks), providing mechanical compatibility with tissue ingrowth patterns as confirmed by micro-computed tomography-based strain mapping. Collectively, these findings demonstrate the convergence of lncRNA biology and precision bioprinting, delivering an off-the-shelf solution for complex tracheal reconstruction that addresses current barriers in graft epithelialization and immunomodulatory response. The study advances the translational potential of bioengineered airway substitutes through molecularly informed design principles.  

Orbital wall fractures often result in midfacial deformities characterized by herniation of orbital adipose and soft tissues into the maxillary sinus, potentially causing endophthalmitis or subbulbar inflammation. However, current orbital reconstruction materials face critical limitations, including inadequate osteogenic capacity and poor osseointegration, predisposing implants to displacement, immune rejection, and infection. To overcome these challenges, we fabricated a three-dimensional (3D)-printed scaffold based on hydroxyapatite/bone morphogenetic protein-2–mineralized decellularized amniotic membrane for orbital defect repair. By precisely modulating the material composition and leveraging advanced 3D printing techniques, we achieved simultaneous control over the scaffold’s physicochemical properties and biological activity. The resulting constructs feature optimized macro- and micro-architectures. This study establishes a novel strategy for orbital reconstruction, addressing both bone volume restoration and functional regeneration, offering a transformative approach for personalized craniofacial repair.

Foreign body reaction (FBR) is a major obstacle to effective osseointegration in bone defect repair. The pore size of scaffolds is a key determinant of FBR; however, its impact on FBR remains controversial, with limited in vivo evidence available. In this study, electrohydrodynamically printed polycaprolactone scaffolds with pore sizes of 100 μm, 200 μm, and 300 μm were fabricated to investigate their effects on macrophage polarization, FBR, and bone regeneration. In vitro experiments showed that the 300 μm group promoted M2 polarization of macrophages, reduced tumor necrosis factor-alpha expression (0.71-fold and 0.81-fold relative to the 100 μm and 200 μm groups, respectively), and increased transforming growth factor-beta 1 expression (1.39-fold and 1.19-fold, respectively), thereby enhancing osteogenic gene expression in MC3T3-E1 cells (Runx2, Col1, and Ocn). Finite element analysis and transcriptomics sequencing revealed that pore size-dependent changes in scaffold stiffness modulate Piezo1 activation, influencing macrophage polarization. In vivo experiments showed that the 300 μm group exhibited the thinnest fibrous capsule (0.78-fold and 0.79-fold relative to the 100 μm and 200 μm groups, respectively), demonstrated enhanced angiogenesis, and achieved better bone regeneration, with increased bone volume/total volume and bone mineral density. These findings indicate that 300 μm pore-sized scaffolds promote bone regeneration by modulating macrophage polarization and attenuating FBR, providing a basis for optimized scaffold design and clinical translation in bone defect repair.

Replicating skeletal muscle architecture remains challenging in 3D bioprinting, as conventional bioinks lack multiscale directional cues. Herein, we propose a next-generation fibrous bioink composed of fragmented electrospun gelatin fibers (f-GFs), uniformly embedded in an alginate/gelatin hydrogel matrix (f-ALG/Gel). Upon microextrusion bioprinting, shear-induced f-GF alignment enabled the fabrication of microfilament-based scaffolds with intrinsic anisotropy. The resulting constructs exhibited high shape fidelity, favorable viscoelastic properties, and physiologically relevant stiffness (Young’s modulus: 16.1 ± 1.7 kPa). In vitro studies using C2C12 murine myoblasts demonstrated that the embedded f-GFs provided strong topographical guidance, enhancing cell alignment and myogenesis. After 14 days of culture, the f-ALG/Gel scaffolds supported a 2.5-fold increase in myotube fusion index and length, alongside reduced angular dispersion. These effects were achieved without the need for biochemical induction with a differentiation medium, underscoring the key role of structural cues at the micro- and nanoscale in C2C12 differentiation and maturation. In conclusion, this work proposes a scalable, cell-compatible strategy to recapitulate the hierarchical organization of skeletal muscle tissue within 3D-printed constructs. The platform holds broad potential for applications in regenerative medicine, skeletal muscle tissue modeling, and the engineering of cultured meat.

The structure, composition, and function of natural bone have long been the focus of bone tissue engineering. However, existing organic–inorganic three-dimensional (3D) printing systems are limited by the stability of hydrogels and the content of inorganic salts, hindering the fabrication of robust 3D scaffolds. In this study, we developed a hydrogel–inorganic particle bioink and implemented a multi-step crosslinking strategy. The organic phase, composed of sodium alginate, gelatin, and chitosan, was combined with β-tricalcium phosphate and crosslinked via ionic pre-crosslinking followed by a Schiff base reaction to form a dual-crosslinked network. The resulting scaffolds exhibited excellent mechanical properties and biomimetic microarchitecture while maintaining shape stability under physiological conditions. Furthermore, the tunable swelling behavior of the hydrogel enabled efficient loading and controlled release of the small molecule epigallocatechin gallate. This composite scaffold demonstrated adjustable swelling, controllable degradation, and significantly enhanced cellular compatibility, providing a novel, efficient, and scalable strategy for repairing complex bone defects and offering new insights for the design and application of 3D-printed bone scaffolds.

Conventional cementless femoral condyles in artificial knee systems are commonly manufactured by casting followed by a surface treatment using plasma spraying or metallic sintering. However, both techniques suffer from weak coating-substrate interfaces that contribute to early loosening and higher revision rates. To overcome this limitation, we employed integrated 3D printing (I3P), an additive manufacturing strategy based on laser powder bed fusion, to fabricate monolithic cobalt-chromium-molybdenum femoral condyles with trabecular-inspired porous architectures. Compared with cast-sintered counterparts, I3P substrates exhibited refined microstructures and superior mechanical performance after hot isostatic pressing, reaching a yield strength of 637.33 MPa, ultimate tensile strength of 1140.00 MPa, and elongation of 27.33%. The I3P femoral condyles also showed enhanced fatigue resistance, withstanding 10 million cycles under a 3000 N load, and demonstrated improved wear behavior against ultrahigh-molecular-weight polyethylene liners. Furthermore, the trabecular-inspired lattice achieved stronger integration with the substrate than sintered coatings, with tensile and shear strengths of 56.09 and 49.97 MPa, respectively. Together, these findings establish I3P as a robust manufacturing strategy that integrates substrate and surface in a single step, enabling the production of durable, osteointegrative femoral condyles with significant potential to improve implant longevity and clinical outcomes in knee joint reconstruction.

Precise delivery of therapeutic agents to targeted sites within the body is a significant challenge, especially in complex and confined physiological environments. Magnetically actuated microrobots offer a promising solution by enabling remote, controllable, and minimally invasive navigation; however, most existing microrobotic systems are fabricated from nondegradable materials and lack controlled drug release capability, which significantly limits their clinical translation. Here, we report 3D-printed biodegradable magnetic microrobots based on gelatin methacryloyl (GelMA) hydrogel capable of controlled therapeutic delivery. Using high-resolution direct laser writing, dual-layer GelMA microrobots with distinct crosslinking degrees were fabricated, enabling tunable degradation and controlled release of encapsulated drugs. The low-crosslinked outer shell functions as a protective barrier that prevents premature drug diffusion, while the highly crosslinked inner core enables sustained drug release during enzymatic degradation. The microrobots demonstrate excellent biocompatibility and controllable degradation in cellular environments. In addition, the integration of a biocompatible magnetic skeleton within the GelMA body enhances mechanical stability and enables precise magnetic actuation. This study presents a versatile strategy for developing biodegradable, magnetically actuated microrobots with controlled therapeutic release, offering strong potential for targeted drug delivery, tissue regeneration, and minimally invasive biomedical applications.  

Soft tissue management is essential in periodontal, orthodontic, and implant therapies, yet autologous grafts remain limited by donor-site morbidity, inconsistent tissue quality, and restricted availability. To address these challenges, we developed an active gingival hydrogel (AGH) composed of gelatin methacrylate, chondroitin sulfate methacrylate, and gingival fibroblasts, which was fabricated into cell-laden hydrogels using extrusion-based 3D bioprinting. The AGH exhibited excellent rheological performance, print fidelity, and interconnected porous microstructures that supported nutrient diffusion and cell migration. Gingival fibroblasts cocultured with the AGH showed robust adhesion, proliferation, and collagen matrix deposition, accompanied by significant upregulation of fibronectin and type I collagen. Mechanistic studies revealed that these effects were mediated through activation of the Wnt/β-catenin and transforming growth factor-β/Smad signaling pathways, which synergistically regulate extracellular matrix remodeling and epithelial keratinization. In vivo experiments demonstrated that AGH implantation significantly enhanced gingival thickness, collagen density, and neovascularization while reducing inflammatory infiltration, as verified by magnetic resonance imaging as well as histological and immunohistochemical analyses. Furthermore, coculture with gingival epithelial cells promoted upregulation of Krt10 and Krt14, indicating improved epithelial differentiation. Collectively, this study establishes a 3D-bioprinted active gingival hydrogel as a biomimetic and functional substitute for autologous grafts, offering a promising strategy for periodontal and peri-implant soft tissue regeneration.

Bone tissue supports the body, enables movement, protects organs, produces blood cells, and stores minerals. In regenerative medicine, bone’s natural healing ability drives the need for engineered solutions to treat fractures, defects, and support implants. This study explores the development of polyethylene terephthalate glycol (PETG) and PETG/bacterial cellulose (BC) composite scaffolds with varying BC contents (10, 15, and 20 wt%) for bone tissue engineering (TE). Scanning electron microscopy and atomic force microscopy revealed porous structures with increasing surface roughness as BC content increased. Water contact angle analysis revealed enhanced hydrophilicity in PETG/BC composites, particularly at higher BC levels. Fourier transform infrared spectroscopy, X-ray diffraction, and differential scanning calorimetry confirmed successful BC integration and interactions with PETG, along with increased crystallinity. Mechanical testing indicated that compressive strength improved with higher BC content, with 20 wt% BC achieving optimal performance. Biological tests using human adipose-derived stem cells displayed enhanced proliferation, differentiation, and mineralization on PETG/BC scaffolds. Among the tested BC scaffolds, the 20 wt% BC scaffold demonstrated the most favorable physical, mechanical, and biological properties. Overall, PETG/BC scaffolds, especially those with 20 wt% BC, display strong potential for future bone TE applications.

Decellularized kidney extracellular matrix (DKM) is an acellular scaffold rich in structural proteins and glycosaminoglycans that can promote tissue regeneration and support organoid culture. Porcine-derived DKM contains abundant extracellular matrix (ECM) components, such as collagen, laminin, and fibronectin, and offers native biochemical cues. However, conventional decellularized ECM hydrogels often exhibit weak mechanical properties, poor printability, and slow gelation, limiting their use in high-throughput applications. Here, we report a visible-light-mediated crosslinking strategy for rapid gelation of DKM based on a tris(2,2’-bipyridyl) ruthenium (II) chloride hexahydrate/sodium persulfate (Ru/SPS) photoinitiator system. Illumination at 405 nm (30 mW/cm2) in the presence of Ru/SPS achieves gelation in about 40 s, yielding a composite DKM–Ru/SPS bioink with tunable modulus by adjusting DKM, Ru, and SPS concentrations. High-fidelity 3D constructs were produced by extrusion bioprinting using a representative formulation (15 mg/mL DKM, 0.25 mM Ru, 2.5 mM SPS). As proof of concept, organoids encapsulated in the DKM–Ru/SPS bioink exhibited viability, proliferation, and lineage marker expression during culture. This work demonstrates a rapid, cell-compatible photocrosslinking approach for DKM–Ru/SPS that integrates organoid culture with 3D bioprinting and drug testing, supporting its potential use as a standardized bioink in tissue engineering and functional screening.

The bioengineering of full-thickness corneal substitutes presents significant challenges, primarily due to the complex stratified structure of the cornea, which consists of the epithelium, stroma, and endothelium, as well as its critical functional requirements, including optical transparency, mechanical stability, and biocompatibility. Herein, we present an integrated fabrication strategy that combines embedded hydrogel bioprinting with subsequent two-dimensional endothelial cell seeding to create biomimetic corneal structures using a gelatin methacryloyl (GelMA)/hyaluronic acid methacryloyl (HAMA) composite hydrogel. The engineered scaffold successfully recapitulates the native cornea’s trilaminar architecture (epithelium, stroma, and endothelium) and exhibits 30–80% optical transparency across the visible spectrum. The hybrid hydrogel exhibits optimal wettability (a contact angle of approximately 50° and minimal swelling of less than 10%) and controlled degradation kinetics, effectively addressing the limitations of single-component hydrogels. The scaffold maintains structural integrity during suturing and supports robust cellular proliferation and migration. Gene expression analysis revealed the phenotypic orientation of seeded cells toward key corneal lineages, with upregulation of epithelial (Klf4 and Pax6), stromal (Col1a1 and Col4a4), and endothelial (Zeb1 and Foxc1) markers. Overall, the bioprinted GelMA/HAMA biomimetic cornea presents a promising proof of concept for a trilayered tissue-engineered corneal construct.

Bone defects caused by various factors have become a persistent challenge in orthopedic clinics, and traditional treatment methods mainly involve the use of artificial bone or autologous bone transplantation. However, these methods have considerable limitations, such as donor site bone loss, immune rejection, and the risk of secondary infection at the donor site. Therefore, considering these limitations and the rapid development of the field of bone tissue engineering, this study adopted light-curing stereolithography three-dimensional (3D) printing technology to design bone scaffold materials. The technology was used to prepare hydroxyapatite (HA)/zirconium dioxide (ZrO2) porous composites with satisfactory mechanical properties as tissue-engineering bone scaffolds. A bone morphogenetic protein- 2-loaded gelatin/chitosan hydrogel sustained-release system was prepared via an emulsification and cross-linking process. Subsequently, rhesus macaque bone marrow mesenchymal stem cells, acting as osteogenic progenitors, were seeded into the system. Novel HA/ZrO2 scaffolds were fabricated using stereolithography 3D printing technology to serve as bone graft substitutes. The resulting scaffold exhibited a 3D interconnected porous structure and showed good biocompatibility and osteoinductive ability in a rhesus macaque lumbar vertebral bone defect model. The results confirmed that the scaffold achieved osteogenic efficiency comparable to that of autologous bone grafting in rhesus macaques. Therefore, the developed scaffold material has promising potential in bone defect repair.  

Development and optimization of advanced bioink formulations for living tissue-engineered scaffolds remain a challenging task. Herein, a nanofibrillated cellulose (NFC)-composited gelatin methacryloyl (G)/alginate (A) formulation (G/A/NFC100) was prepared for 3D bioprinting of mouse preosteoblasts MC3T3-E1, whereby the G/A formulations with a mixed NFC/microfibrillated cellulose and without NFC were included for comparison. The rheological properties of G/A formulation were enhanced by the addition of NFC, as evidenced by a decreased viscosity index characterizing shear thinning behavior from 0.52 (G/A) to 0.19 (G/A/NFC100). To construct 3D scaffolds with excellent shape fidelity while minimizing shear damage to cells during extrusion, the bioprinting conditions of the formulations were optimized based on the parameter optimization index. The G/A/NFC100 scaffold printed at a printing speed of 2 mm/s and a dispensing pressure of 30 kPa from a 27-gauge nozzle displayed a high shape fidelity (printability index of 0.883). The mechanical stability of the crosslinked 20-layered G/A/NFC100 structures were demonstrated by three consecutive press-relax cycles. The successful bioprinting of mouse preosteoblasts using the G/A/NFC100 formulation translated into an increased cell viability (above 97.64%) up to 21 days post-bioprinting. These results emphasize the exceptional potential of NFC-composited G/A formulation for bioprinting of bone tissue analogues for biomedical applications. In addition, the long-term controlled release of ampicillin (67.42% after 72 h) by G/A/NFC100 scaffolds demonstrates the feasibility of utilizing porous cellulose fibers as drug-delivery carriers to enable multifunctionality in bone tissue repair.

The application of bionic porous structures based on Voronoi diagrams in bone defect repair has been extensively studied, with seed distribution characteristics recognized as key parameters affecting the performance of Voronoi scaffolds. In this study, a controllable parametric design method for Voronoi scaffolds was employed to experimentally and numerically investigate the effects of seed count and porosity on the mechanical properties, degradation behavior, mass transfer efficiency, and cell activity of laser powder bed fusion–printed degradable zinc-based Voronoi bone scaffolds. The results revealed the influence mechanisms of seed distribution characteristics on the mechanical properties and deformation modes of Voronoi scaffolds, achieving a 26.9% enhancement in failure stress. Moreover, by adjusting seed distribution, the degradation rate was precisely regulated within the range of 0.027–0.157 mm/year, enabling a 5.8-fold control over the release of zinc ion. Additionally, the effect of seed density on the osteogenic performance and gene expression of mouse pre-osteoblast cells were examined, demonstrating that higher seed densities predominantly upregulated COL1 and ALP expression to promote osteogenic differentiation. Increasing the seed count density elevated COL1 expression to 4.5 times that of the control group. These findings provide a theoretical basis for the clinical application and performance optimization of degradable zinc-based Voronoi bionic bone scaffolds.  

Multimaterial printing using digital light processing (DLP) has progressed from a niche laboratory method to a scalable technology capable of fabricating complex and functional tissue constructs. However, current multimaterial DLP workflows face significant limitations. Material changes typically require repeated washing and reloading steps, which increase print time, raise the risk of cross-contamination or layer misalignment, and ultimately constrain scaffold design complexity and biological relevance. To address these challenges, we present a computational pipeline that significantly improves the efficiency, precision, and usability of DLP for multimaterial bioprinting. Our system includes three key innovations: (i) a high-resolution segmentation and material-labeling method using computer graphics techniques for accurate material assignment in Standard Tessellation Language (STL) models; (ii) a computer vision-based algorithm for real-time detection and correction of material interference or contamination; and (iii) a GPU-accelerated layer sequencing method that supports rapid, precise material switching within single-layer projections. Experimental validation demonstrates improved print fidelity, reduced processing time, and higher material resolution. We further showcase the practical utility of our system by bioprinting a multimaterial tissue construct composed of a poly(ethylene glycol) diacrylate-based scaffold integrated with a gelatin methacryloyl-based cell-laden microenvironment. This work represents a significant step toward enabling scalable, high-resolution, and biologically functional scaffold fabrication for advanced tissue engineering applications.

Psoralen inhibits osteoclast activity and bone resorption while enhancing osteoblast activity and bone formation. However, its role in modulating macrophage polarization to enhance osteoblast function and scaffold osseointegration under osteoporotic conditions remains underexplored. We fabricated Voronoi-structured metal scaffolds by 3D printing and evaluated psoralen in vitro in a macrophage– bone marrow mesenchymal stem cell co-culture system using serum from psoralen-treated rats, and in vivo in an osteoporotic bone-defect model with oral psoralen administration. The results demonstrated that psoralen treatment promoted M2 macrophage polarization, increased the M2/M1 ratio, and upregulated osteogenic gene expression in vitro. Improved bone formation parameters—including bone volume fraction, trabecular thickness, and trabecular number—around the implanted scaffolds were observed in vivo. The findings suggest a synergistic effect between gradient scaffold structures and psoralen in enhancing M2-mediated osteogenesis. Taken together, these findings may provide novel strategies for improving bone repair and prosthesis integration in osteoporosis.  

Schatzker type VI fractures are complex tibial plateau injuries characterized by multiple fracture lines and complete separation between the plateau and the shaft. These features reduce the effectiveness of standard commercial fixation plates, which often fail to conform to the irregular anatomy. Patient-specific plates, tailored to individual bone geometry, offer improved anatomical fit and fixation. This study aims to compare two patient-specific designs, based on 3D reconstruction (3DP) and generative design (GDP), with a conventional commercial plate (CP). To enable rapid and costeffective evaluation, all designs were first prototyped in poly(lactic acid) using fused deposition modeling. In bending tests, both 3DP and GDP were significantly stiffer than CP, with stiffness increases of 23.8% and 10.0%, respectively. In biomechanical compression tests, both patient-specific designs exhibited approximately 15% lower displacement than CP under a 750 N load. Based on these results, the GDP design was selected for metal additive manufacturing using laser powder bed fusion. The metal printed GDP was tested under a compressive load of 750 N and showed a mean displacement of 2.11 ± 0.01 mm, remaining below the commonly accepted clinical threshold of 3 mm. This work highlights the potential of combining PLA-based prototyping with targeted metal validation to support surgical decision-making and streamline implant development.

Effective fixation of the endotracheal tube is essential to prevent displacement, unplanned extubation, and pressure injuries (PIs), which remain common complications with traditional fixation methods. Advances in three-dimensional (3D) printing technology offer opportunities to design personalized devices that may improve airway security and patient outcomes. However, no prior study has evaluated the use of 3D-printed fixation devices as an alternative to traditional methods. We aim to design and evaluate the effectiveness of an endotracheal tube fixation device produced using 3D printing technology in patients receiving mechanical ventilation. In a single-center, prospective, non-concurrent, controlled cohort trial, patients with an expected duration of mechanical ventilation exceeding 24 hours were stratified into an observation group (using a 3D-printed device; n = 51) and a control group (using a traditional device; n = 97). The primary endpoints were tracheal tube displacement and unplanned endotracheal extubation (UEE). The incidence of endotracheal tube displacement was 1/51 (1.9%) in the observation group vs. 12/97 (12.4%) in the control group (odds ratio [OR]: 6.28, 95% confidence interval [CI]: 1.91–21.05), yielding a 99% probability of benefit (POB). UEE incidence was 0/51 in the observation group, whereas it was 4/97 (4.1%) in the control group (OR: 5.26, 95% CI: 1.08–26.31), yielding a 98% POB. Lip PI occurred in 0/51 patients in the observation group vs. 10/97 (10.3%) patients in the control group (OR: 8.72, 95% CI: 2.11–35.98), yielding a 99% POB. The observation group exhibited significantly higher nurse satisfaction scores compared to the control group (p = 0.015). There were no significant differences in facial PI between the two groups. These findings suggest that the 3D-printed device reduced the incidence of tracheal tube displacement, UEE, and lip PI, while improving nurse satisfaction.

Bone defects pose a high risk of non-union and permanent disability, making effective bone regeneration a critical focus in the development of bone repair materials. Current research primarily emphasizes enhancing the single osteogenic function of bone repair materials, while neglecting the impact of the complex microenvironment in bone defect areas. This has resulted in the failure of many developed bone repair materials to achieve effective in vivo bone regeneration. In this study, a multifunctional near-infrared light-responsive black phosphorus (BP) bone repair scaffold was fabricated via low-temperature deposition 3D printing. In vitro characterization demonstrated that the scaffold possesses a cancellous bone-like structure, moderate compressive strength, and cytocompatibility, with the ability to promote osteogenesis under inflammatory conditions. In vivo studies further confirmed its favorable photothermal responsiveness, enabling photothermal therapy (PTT) to accelerate bone regeneration while reducing inflammation in the defect area. These findings indicate that the multifunctional BP scaffold achieves superior bone repair outcomes through synergistic effects of anti-inflammation, promotion of osteogenic differentiation, and PTT, thereby improving the success rate of defect repair. Moreover, the simple fabrication process and satisfactory therapeutic efficacy of this multifunctional BP scaffold highlight its high potential for clinical translation.

Bacterial adhesion and biofilm formation are critical issues for 3D-printed dental resin. This study aims to develop a novel cetylpyridinium chloride (CPC)-based antibacterial photocurable resin for vat photopolymerization (VPP) 3D printing and evaluate its printability, mechanical properties, antibacterial activities, and CPC-release behavior for potential use in dental prostheses and orthodontic devices. Photocurable resins containing 0–3 wt.% CPC were formulated from methacrylate and acrylate monomers. Printability of the photocurable resins was assessed by measuring viscosity, cure depth, over-curing, and the degree of conversion. The photocurable resins were printed using a VPP 3D printer, and the resulting specimens were evaluated for mechanical properties using three-point bending and Vickers hardness tests. Antibacterial activity against Streptococcus mutans was examined by bacterial viability and plaque-formation assays. CPC-release behavior was analyzed by UV–visible spectroscopy. CPC incorporation up to 3% slightly increased resin viscosity, cure depth, and over-curing while maintaining adequate printability. The degree of conversion was not significantly affected by CPC content. The 1% CPC-loaded printed resin exhibited mechanical properties comparable to the CPC-free control, whereas 3% CPC markedly reduced them. The 1% CPC-loaded resin showed strong antibacterial activity, achieving an antibacterial activity value of 5.6 (>99.99% bacterial reduction), and demonstrated sustained plaque inhibition. Sustained CPC release from the printed resins was confirmed throughout the 14-day evaluation period. These results demonstrate that 1% CPC-loading provides an optimal balance among printability, mechanical properties, and antibacterial performance. The developed material shows potential for application in 3D-printed dental polymer-based prostheses and orthodontic devices.  

Three-dimensional bioprinting ushers a transformative change in tissue engineering, providing unparalleled opportunities for regenerative medicine by precisely fabricating intricate, biomimetic tissues. To achieve true organ-level in vitro tissue construction, various advanced bioprinting technologies have been developed. Among these, acoustic droplet bioprinting technology, owing to its excellent biocompatibility and multi-sample handling capabilities, offers an efficient, non-contact liquid-handling approach for tissue engineering applications. To meet the printing structure’s geometric precision requirements, meticulous control of printing parameters is essential. However, the selection of acoustic droplet printing parameters still depends heavily on empirical values, which often leads to print outcomes that fall short of optimal standards. In this paper, a parameterized droplet dispensing method for multi-sample droplet excitation was established. This method introduces a unified scaling parameter based on the product of surface tension and viscosity, integrating acoustic stress and fluid response into a single dimensionless quantity, thereby enabling precise adjustment of droplet velocity. The relative error between the initial velocity measured using this method and the preset velocity was less than 6.7%. Next, we analyzed the effects of droplet overlap distance and the Weber and Ohnesorge numbers on printed line-width consistency. By employing optimized printing parameters, we achieved controllable printing of patterned hydrogel meshes suitable for cell culture. The results demonstrated that the lengths and widths of the nine sub-meshes exhibited high consistency. These advances move acoustic droplet bioprinting from an experience-driven process toward a more systematic, predictive, and reproducible parameter-optimization strategy.

Wound healing is a complex process that ensures tissue recovery and survival, but remains challenging to manage, particularly in deep wounds and burns. Conventional treatments require specialized operators, repeated interventions, and high costs. In extreme environments, such as space, the absence of dedicated facilities and personnel further complicates wound care, highlighting the need for novel, automated, and easy-to-use therapeutic strategies. In this study, we developed and validated a protocol that combines in situ 3D bioprinting with near-infrared (NIR) laser irradiation to promote graft integration and accelerate wound repair. The approach was tested in the leech model of a skin wound with tissue loss, selected for its suitability in reproducing key aspects of tissue regeneration and for its relevance in space-oriented regenerative medicine experiments design comprised four steps: (i) identification of biomaterial inks compatible with the wound environment; (ii) application of an optimized in situ 3D bioprinting protocol; (iii) NIR laser irradiation to stimulate graft integration; and (iv) histological and immunofluorescence evaluation of healing outcomes compared to controls (bioprinting only, laser only, and untreated). Results demonstrated that the integrated protocol significantly improved wound healing, preventing fibrosis and enhancing re-epithelialization, fibroblast activation, and transdifferentiation. The combined treatment outperformed all control conditions, confirming the synergistic effect of In situ bioprinting and laser irradiation. This work introduces an advanced wound care strategy integrating biofabrication and photobiomodulation. The protocol shows high potential for clinical translation, with applications not only in conventional medical settings but also in extreme environments such as space.  

Bone defects resulting from trauma, infection, or tumor resection often exceed the self-healing capacity of bone tissue, requiring bioactive and mechanically robust repair materials. In this study, a composite scaffold was developed via in situ polymerization of a hydroxyethyl methacrylate/sulfobetaine methacrylate (HMSM) hydrogel with a three-dimensional-printed nano-hydroxyapatite/polylactic acid (NP) gradient scaffold to achieve controlled simvastatin (SIM) delivery and enhanced osteogenesis. The HMSM hydrogel served as a hydrophilic and biocompatible matrix, while the NP scaffold provided mechanical strength and structural support. SIM was incorporated into the hydrogel–scaffold composite (SIM@HMSM/NP) to establish a sustained drug-release system. The composite exhibited a smooth microstructure, uniform pore distribution, and a gradient architecture mimicking native bone. Mechanical testing demonstrated improved compressive strength compared with individual components, and in vitro studies revealed stable SIM release over 24 days with a degradation profile compatible with bone regeneration. The SIM@HMSM/ NP demonstrated excellent cytocompatibility, promoting the proliferation and osteogenic differentiation of bone marrow mesenchymal stem cells, and significantly enhanced bone formation in a rat calvarial defect model. These findings suggest that the SIM@HMSM/NP scaffold provides a promising strategy for sustained drug delivery and accelerated bone regeneration in critical-sized bone defects.  

The repair of deep skin defects involving subcutaneous tissue urgently requires vascularized skin substitutes that can provide immediate blood perfusion. However, existing engineering strategies struggle to construct multi-level vascular networks in vitro. This study aims to develop a multi-layered skin substitute with both biomimetic structure and physiological function, incorporating a perfusable “small-micro” hierarchical vascular system. We employed a composite coaxial–extrusion bioprinting strategy. First, a composite bioink consisting of 2% sodium alginate and 5% gelatin methacryloyl was formulated and evaluated for its printability and biocompatibility. Subsequently, using an ionic-photo dual-crosslinking coaxial printing technique, we fabricated subcutaneous small vessels with controllable dimensions and adequate mechanical properties. Finally, small vessels were integrated with an extrusion bioprinted dermal microvascular network and an epidermal layer to form a complete “small-micro” vascular pathway. This multi-layered construct was designed to mimic the stratified characteristics of natural skin. In vitro functional experiments confirmed that the epidermis possesses an excellent barrier function, and the subcutaneous small vessels demonstrated an effective capability for delivering drug molecules. The dual-crosslinking coaxial printing and composite manufacturing strategy proposed in this proof-of-concept study successfully constructed vascularized skin with a hierarchical tubular structure, offering a new solution with clinical translation potential for treating full-thickness skin defects.

Patellar fractures, especially transverse and comminuted types, often present mechanical challenges that exceed the capabilities of conventional fixation constructs. This study develops a topology-optimized metal three-dimensional-printed dual-compression patellar plate designed to improve fragment stability while maintaining appropriate intraoperative rigidity. The plate design was first refined using an original anatomically assembled thin bone plate, which underwent finite element analysis and topology optimization to preserve primary load-bearing paths and reduce excessive stiffness. The optimized structure was subsequently fabricated using selective laser melting with Ti-6Al-4V and mechanically evaluated in accordance with American Society for Testing and Materials F382 standards. Static four-point bending tests demonstrated a proof load (P) of 257.31 ± 5.40 N and structural bending stiffness of 1.10 ± 0.01 N·m². Fatigue testing revealed runout at 15% P, while failure occurred at higher load levels (25% P & 30% P), revealing two distinct modes: plate fracture at topology-optimized transition zones and locking-screw shear failure. Static tensile testing revealed that dual-compression fixation significantly (p<0.05) enhanced load-bearing capacity compared with single-compression fixation for both C1 (712 N vs. 517.5 N) and C3 (253.75 N vs. 205.25 N) fracture models. Dynamic knee-extension testing demonstrated that dual compression markedly reduced medial–lateral fracture micromotion, decreasing C3 gaps from 0.348–0.534 mm to 0.078–0.107 mm without increasing quadriceps reaction force. Overall, the topology-optimized dual-compression patellar plate provides mechanically validated interfragmentary stability, effective micromotion control, and a well-defined fatigue performance envelope, supporting its potential as an advanced fixation solution for clinically challenging patellar fractures.