Commercial photopolymer resins used in additive manufacturing are typically designed to be chemically inert, ensuring print fidelity and long-term stability. However, the ability to chemically functionalize printed surfaces would significantly expand the integration of commercial 3D printing with bioanalytical and lab-on-a-chip systems. Here, we introduce a materials-design strategy in which chemical functionality is incorporated directly into the resin formulation. Addition of a copolymerizable acrylamide monomer produces an activation-ready photopolymer resin with surface-accessible functionality suitable for post-print modification, thereby reducing dependence on geometry-sensitive surface-treatment methods. The modified resin retains low autofluorescence and micron-scale printing resolution, maintaining compatibility with fluorescence-based microfluidic assays. The functionalized surface enables glutaraldehyde-mediated immobilization of model proteins, including bovine haemoglobin and bovine serum albumin. Successful protein immobilization was verified by protein staining and wettability measurements, while selective recognition by fluorescent molecularly imprinted nanoparticles revealed highly specific binding under static and flow conditions, with dissociation constants (Kd) of 2.57 and 53.0 nM for target binding. By incorporating modification-ready functionality into a commercial photopolymer resin while preserving its printing and optical properties, this work provides a practical strategy for the rapid fabrication of protein-functionalized 3D-printed microfluidic devices.
Bone tissue exhibits pronounced spatial heterogeneity in structure, composition, and mechanical properties, which is essential for effective load bearing and regeneration. Conventional homogeneous scaffolds often fail to reproduce these features, thereby limiting their functional and clinical performance. Recent advances in bioprinting have enabled the fabrication of non-uniform bone scaffolds with spatially controlled architectural, material, and biological gradients tailored to site-specific functional demands. This review critically examines current strategies for the design and fabrication of non-uniform bone scaffolds. Bioprinting technologies that enable gradient control, including multi-material extrusion, microfluidic-based printheads, and hybrid manufacturing approaches, are discussed. Material strategies such as composite gradients, hierarchical porosity, and nano- to micro-scale compositional variations are analyzed in terms of their mechanical performance and biological relevance. In addition, spatially regulated bioactive modulation using cells, growth factors, and extracellular vesicles is reviewed from a practical and translational perspective. Imaging-guided and patient-specific case studies are highlighted to illustrate the clinical potential of non-uniform scaffold designs, while key technical, biological, and regulatory challenges are critically assessed. Finally, emerging directions, including 4D bioprinting, computational digital twins, and standardized manufacturing pathways, are discussed. Overall, this review underscores that function-driven, non-uniform scaffold design represents a promising route toward more effective and clinically translatable strategies for bone regeneration.
The development of models for neurodegenerative and neurovascular diseases has become crucial for understanding complex biological processes, including the progression of Alzheimer’s disease, stroke, and glioblastoma. Traditional in vitro systems have significant limitations in replicating the intricate interactions between the blood-brain barrier (BBB), endothelial cells, and surrounding tissues. This review explores a novel strategy to enhance disease modeling technology through the integration of 3D bioprinting with microfluidic chips. This advanced approach enables the precise creation of dynamic tissue constructs that emulate the physiological microenvironment of the neurovascular unit, facilitating studies on drug cytotoxicity, cell differentiation, and intercellular signaling. Furthermore, the platform offers promising applications for identifying therapeutic targets and designing miniaturized biosensor-embedded MEMS (micro-electro-mechanical systems) and NEMS (nano-electro-mechanical systems) for the sensitive detection of disease biomarkers. The integrated platform further incorporates design modifications, including optimized microchannel geometry, bioprinted three-dimensional cellular architectures, and improved spatial organization of biological components within the microfluidic chip. These engineering advancements enhance cell viability, physiological cell-cell and cell-matrix interactions, nutrient and oxygen diffusion, and overall biomimetic functionality, while clearly demonstrating the contribution of 3D bioprinting to improved device performance, experimental reproducibility, and biological relevance for neurovascular disease modeling and therapeutic evaluation. The system is particularly suited for modeling the pathophysiological conditions of neurovascular and neurodegenerative diseases, such as Alzheimer’s disease, stroke, and brain cancer (glioblastoma), in a controlled and reproducible manner. This capability was demonstrated through preclinical and co-clinical drug trials, generating functional data to support effective therapeutic interventions. Additionally, the study highlights the creation of pathophysiological models incorporating neural, endothelial, and adjacent cell types to investigate neural–microvascular interactions. The integrated platform serves as a powerful tool for evaluating drug efficacy, deciphering disease mechanisms, and advancing personalized medicine approaches. These findings underscore the transformative potential of combining 3D bioprinting and microfluidic technologies to develop highly functional models for neurodegenerative and neurovascular diseases, offering significant value for translational biomedical research.
Three-dimensional (3D) printing has advanced additive manufacturing by enabling the fabrication of complex, application-specific structures across biomedical, pharmaceutical, and industrial fields. However, conventional layer-by-layer deposition presents inherent limitations, including slow production rates, material constraints, and structural inconsistencies. This review critically evaluates recent innovative developments in advanced 3D bioprinting/biofabrication technologies, namely Volumetric Additive Manufacturing (VAM), Freeform Reversible Embedding of Suspended Hydrogels (FRESH), and Embedded Multi-Material Extrusion Bioprinting (EMMB), which introduce novel fabrication strategies to overcome these limitations. Techniques are examined in terms of their working principles, material compatibility, resolution, structural fidelity, and suitability for tissue engineering, drug delivery, and regenerative medicine. The review also addresses ongoing challenges, including bioink optimization, interfacial control in multi-material systems, and achieving scalability without compromising functionality. Future perspectives include the integration of hybrid manufacturing, artificial intelligence (AI) for real-time process optimization, and microscale fabrication strategies targeting medical microdevices and micro-electro-mechanical systems (MEMS). By providing a comparative overview of conventional and emerging 3D printing techniques, this work outlines a path toward the next generation of high-precision, multifunctional biofabrication platforms capable of supporting personalized therapeutic solutions and complex prototyping across diverse domains.
Can additively manufactured TPMS lattices be systematically benchmarked to guide patient-specific orthopaedic scaffold design? Triply periodic minimal surface architectures offer high surface area, fully interconnected porosity, and tuneable mechanical behaviour, but direct experimental comparisons across topologies within clinically relevant manufacturing limits remain underexplored. Here, fifty-four Ti-6Al-4V TPMS lattices (Gyroid, Diamond, Split-P) were fabricated using laser powder bed fusion (l-PBF) with wall thicknesses of 100-500 μm and unit cell sizes of 0.75-2.0 mm3. Quasi-static compression testing revealed strong geometry-dependent mechanical behaviour, with effective Young's modulus ranging from 6.3 to 107 GPa, yield strength from 125 to 1030 MPa, and strain energy density from 2.23 to 12.66 MJ/m3. Increasing wall thickness increased stiffness and energy absorption, while increasing unit cell size consistently reduced stiffness across all architectures. Diamond and Split-P lattices exhibited higher average energy absorption (≈ 5.1 MJ/m3) compared with Gyroid (≈ 4.05 MJ/m3), whereas Gyroid structures showed more stable deformation behaviour. Comparison with Gibson-Ashby scaling revealed systematic deviation at relative densities above ≈ 0.45, highlighting topology-dependent load transfer and manufacturing effects. To translate these results into design guidance, a hybrid decision-making framework integrating Analytic Hierarchy Process, Target-Driven Decay, and TOPSIS (AHP-TDD-TOPSIS) was implemented to rank scaffold configurations against mechanical and biological criteria. The results provide experimentally validated guidance for patient-specific TPMS scaffold selection and orthopaedic implant optimisation.
The biofabrication of perfusable, multiscale vascular networks is a critical prerequisite for engineering thick functional tissues. Replicating the native vascular hierarchy, from millimeter-scale arteries to micrometer-scale capillaries, requires integrating advanced fabrication techniques, biocompatible materials, and multiple cell types. This review evaluates the state-of-the-art in vascular network biofabrication, systematically analyzing the interplay between fabrication modalities, biomaterial selection, and cellular strategies for vessel assembly. Although architectural control has advanced, non-adherence to standardisation in quality control remains a principal constraint on translation from bench to bedside. Inconsistent assessment of crucial functional metrics such as burst pressure, compliance, perfusion rates, and patency impedes direct comparison between studies and presents a significant barrier to regulatory approval. The review further examines common failure modes, including structural collapse and thrombosis, linking them directly to choices in design, materials, and cellularization. By outlining quantitative benchmarks and analysing emerging technologies such as computational design and hybrid printing, this review provides a framework for future research and articulates the case for consensus standards to support clinical realisation of thick-tissue vascular engineering.
Corneal stromal bioprinting requires bioinks that combine optical transparency, structural stability, printability, and a biologically instructive microenvironment capable of maintaining keratocyte quiescence. Here, we report the development of GAME, a composite bioink integrating gelatin methacryloyl (GelMA) with murine amniotic membrane extract (AME), and comprehensively characterize its biochemical composition, physicochemical properties, bioprintability, and ability to support human induced pluripotent stem cell-derived corneal stromal keratocyte-like cells (hiPSC-CSKs).Quantitative proteomic analysis demonstrated that AME possesses a conserved proteome enriched in collagens, small leucine-rich proteoglycans, fibronectin, nidogens, and growth factor-associated regulatory proteins, with compositional consistency across independently prepared batches. Incorporation of AME into GelMA generated a transparent hydrogel with an interconnected porous microarchitecture, sustained structural stability, and elastic-dominant viscoelastic behavior within the range reported to support corneal stromal cell function. The GAME bioink also tolerated surgical suturing and enabled reproducible extrusion bioprinting of corneal-scale constructs with high printability and geometric fidelity following photocrosslinking. Bioprinted hiPSC-CSKs embedded in GAME exhibited high viability throughout 21 days of culture while maintaining expression of the keratocyte-associated markers keratocan, ALDH3A1, and CD34, with minimal α-smooth muscle actin (α-SMA) expression, indicating preservation of a quiescent, non-fibrotic stromal phenotype after bioprinting.These findings establish GAME as a compositionally defined, mechanically robust, and cytocompatible bioink for corneal stromal tissue engineering. More broadly, this work demonstrates that proteomic characterization of biologically derived supplements provides a rational framework for the development of reproducible and biologically instructive bioinks for corneal tissue engineering.
Tissue engineering and regenerative medicine have created significant opportunities for designing new approaches to restore, substitute, or regenerate injured tissues and organs. Among the emerging technologies supporting this advancement, three-dimensional (3D) bioprinting has gained particular attention due to its capability to produce tailored constructs that replicate many of the biological and mechanical characteristics of natural tissues. Within this field, photocrosslinkable bioinks have gained significant attention as a viable and versatile option. By leveraging light-induced reactions, these bioinks enable rapid and spatially controlled gelation, providing tunable mechanical characteristics and superior print fidelity for fabricating functional tissue-like structures. This review presents a comprehensive overview of the principles and mechanisms underlying photocrosslinkable bioinks, focusing on key photocrosslinking strategies, alongside the role of photoinitiators in modulating these processes. It further delves into the classification of photocrosslinkable bioinks, encompassing synthetic polymers, natural hydrogels, and cell-laden formulations, and discusses essential formulation parameters. The review also evaluates the advantages and limitations of these bioinks, supported by case studies that illustrate their various biomedical applications. Ultimately, current challenges are addressed alongside future directions and technological innovations poised to advance clinical translation in this rapidly evolving field.
Bone defects are serious abnormalities caused by accidental fractures, disease, or congenital defects that can severely impact a patient's quality of life. Gold standard traditional techniques, including autografts and allografts, are limited in their reparative ability, leading to advances in bone tissue engineering (BTE). Currently, biomaterials-based 3D implants have acquired a pivotal role in treating bone defects. Specifically, bioprinting with natural polymer-based bioinks has become a widely used method for repairing bone defects. Biopolymer-based composite bioink has attracted sustained interest in the field of BTE due to its ability to print and generate complex hierarchical architectures that mimic bone environments, thereby promoting osteogenic activity. Despite these advantages, there is still a lack of clear understanding of the limitations of natural hydrogel-based bioinks in terms of mechanical strength, printability, and in vivo performance. Here, the challenges associated with the development, printing, and applications of natural hydrogel-based bioinks in the field of BTE are discussed. The specific criteria of hydrogels for application in the repair of bone defects are discussed, including material and biological properties. The various printing techniques adopted for 3D printing of hydrogels are investigated, including extrusion-based, laser-based, and inkjet-based printing. The limitations of commonly used natural hydrogels are analyzed in both preclinical and clinical studies, particularly their poor mechanical properties, fast degradation, and limited ability to support bone formation in vivo. The review also assesses recent advances in the use of natural polymer-based bioinks in animal models and clinical scenarios. In conclusion, a mismatch between current bioink design and clinical requirements is defined and future directions are proposed to enhance translational potential, while summarizing the key advantages and drawbacks of natural hydrogel-based bioprinting for BTE.
Background Traditional fabrication of custom-made orthoses and prostheses (O&P) is labor-intensive with wide variability, high cost, and long production cycles. AM (Additive Manufacturing), also known as 3-Dimensional printing, has emerged as a game-changing digital alternative. Objective This scoping review strives to systematically synthesize and critically analyze the state-of-the-art in AM for the production of O&P devices in terms of technology innovation, material advancements, and comparative capabilities and limitations. Methods Employing the Joanna Briggs Institute methodology, a systematic review of four large databases (PubMed, Scopus, Web of Science, and EMBASE) was conducted in August 2025. Peer-reviewed articles released between January 2020 and August 2025 were considered for inclusion. After screening, 107 articles were shortlisted for final analysis and thematic categorization. Results The analysis demonstrates that AM, mainly Fused Deposition Modelling, using materials such as Polylactic Acid (PLA), Thermoplastic Polyurethane, and Nylon, enables unprecedented customization, while significantly reducing production costs (25%-95%), manufacturing time (from 14 days to approximately 16 h), and device weight (by approximately 50%). 3D-printed PLA orthoses demonstrate superior mechanical strength compared to traditional plaster casts (yield force: 586 N vs. 257 N). Among the notable developments are the incorporation of sensors and the use of topology optimization and finite element analysis to build lightweight but robust structures. Applications stretch from limb orthoses to limb prosthetics to cosmetic prosthesis. However, issues include non-standardized techniques, poor long-term durability data, and material anisotropy. Conclusion AM is a revolution in O&P, which is facilitating patient-specific, economical devices. In future research, to achieve mainstream clinical acceptance, material durability with new composites needs to be addressed, long-term clinical trials must be conducted, and standard regulatory guidelines must be developed.
Bioprinting has emerged as a transformative platform for engineering bone and cartilage tissues; however, its clinical translation is currently limited by the lack of scalable, reproducible, and regulatory-compliant bioink manufacturing. This review provides a comprehensive evaluation of current challenges, advancements, and strategies for the scale-up of bioink manufacturing, with a specific focus on bone and cartilage bioprinting applications. The key topics addressed include mechanical performance, cell viability preservation, reproducibility, batch-to-batch consistency, sterility assurance, and regulatory compliance. Emerging methods, including bioreactor-based cell expansion, continuous bioprocessing, and hybrid biomaterials, are critically assessed for their potential to enhance scalability while maintaining biological functionality and manufacturing reproducibility. Future directions for industrial-scale bioink manufacturing are discussed with particular emphasis on manufacturing-critical requirements, including sterility assurance, endotoxin control, batch-to-batch consistency, and clearly defined release criteria, each of which is essential for regulatory approval and clinical translation. Collectively, these developments reflect a shift from manual bioink preparation toward automated, validated, and scalable manufacturing pipelines that advance the clinical deployment of patient-specific regenerative therapies for musculoskeletal applications.
Successful 3D bioprinting requires bioinks that combine appropriate mechanical and biological properties to support tissue engineering applications. Beyond these fundamental requirements, increasing attention has been devoted to materials with advanced functionalities, such as self-healing behavior, which can more closely replicate selected adaptive features of native tissues and offer advantages in dynamic environments where mechanical integrity is critical. Nevertheless, despite the growing interest in self-healing hydrogels, their development for bioprinting remains limited, particularly for vat photopolymerization, which is increasingly used in bioprinting due to its higher resolution when compared to extrusion-based methods.This study addresses this gap by formulating and characterizing a nanocomposite bioink based on GelMA and waterborne polyurethane nanoparticles, designed to combine intrinsic self-healing with compatibility with both extrusion-based bioprinting and vat photopolymerization. Waterborne polyurethane nanoparticles with a diameter of 50 nm were synthesized and incorporated into a GelMA-based matrix to introduce autonomous self-healing without requiring an external trigger. The resulting material was characterized in terms of swelling behavior, degradation under physiological conditions, cytocompatibility, and rheological properties. The hydrogel exhibited a shear modulus of 8 kPa, within the range of soft hydrogel matrices, effective self-healing capability, along with a slower degradation rate than the control formulation, supporting its potential as a biofabrication platform for further biological investigation.
Achieving high shape fidelity remains a primary challenge in extrusion-based bioprinting, where the viscoelastic nature of hydrogels typically leads to "die swell", a post-extrusion expansion that compromises structural accuracy. This study presents a systematic investigation into the die swell phenomenon by analyzing the complex interplay between process parameters (pressure, temperature, nozzle diameter) and material rheology. Using a Design of Experiments (DOE) approach on functionalized collagen hydrogels, we isolated the main effects of process variables and identified significant interactions that modulate the swelling behavior. Crucially, by integrating rheological data, specifically the ratio between the first normal stress difference (N1) and shear stress (τ), with process kinematics, we developed a robust numerical model capable of predicting the extent of die swell. This model not only validates the theoretical framework of Tanner’s law in a bioprinting context but also provides a predictive tool for process optimization. These findings offer a foundational dataset and a mathematical framework that pave the way for future AI-driven strategies and machine learning algorithms aimed at real-time error correction in biofabrication.
Bioprinting is an emerging 3D printing technology that utilizes biomaterials and cells to print tissues and organs with precise geometry and cell distribution. Bioprinting in suspension enables biofabrication of tissues and organs using low viscosity bioinks. Here, we report on suspension bioprinted bioactive vascular-like tubes employing the biocompatible polysaccharide gellan gum (GG) as the primary biomaterial for the bioink formulation. To enhance the structural integrity of GG and its printability, the nanosilicate laponite (Lap) was incorporated. The addition of Lap increased structural support, while its ability to adsorb and release bioactive molecules was leveraged by functionalizing the bioinks with platelet-rich plasma (PRP), which is rich in growth factors associated with vascularization. The introduction of PRP into the Lap-containing GG hydrogels created a composite matrix acting as a reservoir of bioactive growth factors to support angiogenesis. The incorporation of PRP within GG-Lap composite bioinks enhanced Wharton's jelly-derived mesenchymal stem cells proliferation, migration, and angiogenesis-related cellular functions. Increased levels of angiogenic markers and extracellular matrix formation in vitro and in vivo were demonstrated. The functional bioinks offer a promising platform for 3D bioprinting of patient-specific bioactive tubular structures advancing vascular tissue engineering.
