Design of bone scaffolds with calcium phosphate and its derivatives by 3D printing: A review

Enhanced mechanical strength and bioactivity of 3D-printed β-TCP scaffolds coated with bioactive glasses

3D printing in scaffold production offers a promising approach, enabling precise architectural design that closely mimics the porosity and interconnectivity of natural bone. β-Tricalcium phosphate (β-Ca₃(PO₄)₂, β-TCP), with a chemical composition similar to the inorganic component of bone, is a widely used material for scaffold fabrication. Recent advances have made it possible to functionalize ceramic scaffolds to improve bone regeneration and repair while enabling the in situ release of therapeutic agents to treat bone infections. In this study, 3D-printed β-TCP scaffolds were coated with bioactive glasses, 45S5 (45SiO₂ - 24.5Na₂O - 24.5CaO - 6P₂O₅, wt.%) and 58S (58SiO₂ - 33CaO - 9P₂O₅, wt.%), using sol-gel solutions through a vacuum impregnation technique. The β-TCP ink exhibited pseudoplastic behavior, which facilitated its 3D printing. The resulting scaffolds demonstrated high fidelity to the designed model, featuring well-aligned filaments and minimal collapse of the lower layers after sintering. Elemental mapping revealed that 45S5 glass formed a surface coating around the scaffold struts, whereas 58S glass penetrated the internal structure, this occurred due to their differing viscosities at high temperatures. Compared to uncoated β-TCP scaffolds, the coatings significantly improved mechanical strength, with increases of 63% and 126% for scaffolds coated with 45S5 and 58S, respectively. Bioactivity was confirmed through an apatite mineralization assay in simulated body fluid, which demonstrated hydroxyapatite precipitation on both coated scaffolds, albeit with distinct morphologies. Since this study focused on acellular scaffolds, further research is necessary to fully explore the potential of these bioactive scaffolds with optimized mechanical properties in biological systems.

Role of 3D printing in healthcare: A comprehensive review on treatment and training

Additive manufacturing (AM) is revolutionizing healthcare by enabling the creation of customized 3D printed (3DP) medical equipment, implants, orthoses, prosthetics, drugs, and organs. With the availability of different types of materials suitable for 3DP and healthcare applications, this technology allows for the precise fabrication of patient-oriented prosthetics, dental implants, and orthopedic devices, significantly improving fit and functionality. Additionally, 3DP drugs, such as Oral Dispersible Formulations (ODFs) and polypills, are surpassing the traditional "one pill fits all" concept, offering more tailored medication solutions. This innovation also supports the development of personalized medications and bioprinted tissues, opening the way for advancements in regenerative medications and tailored therapies. 3D-bioprinted organs are addressing the growing demand for organ transplants. In surgical planning, 3D-printed anatomical models provide students and professionals with hands-on practice, which is crucial for skill development and understanding complex anatomies. Surgeons can also practice and refine techniques before actual procedures, enhancing precision and improving outcomes during real operations. This paper focus on highlighting the progression and motivations behind the cross-disciplinary applications of AM within the healthcare sector providing customized medical devices, drug delivery systems and diagnostic tools for personalized treatment and skill refinement. This paper is designed for a broad audience, including manufacturing professionals and researchers, who are interested in exploring the medical implications of this transformative technology.

Evaluation and optimization of physical, mechanical, and biological characteristics of 3D printed Whitlockite/calcium silicate composite scaffold for bone tissue regeneration using response surface methodology

Calcium phosphate-based bioscaffolds are used for bone tissue regeneration because of their physical and chemical resemblance to human bone. Calcium, phosphate, sodium, potassium, magnesium, and silicon are important components of human bone. The successful biomimicking of human bone characteristics involves incorporating all the human bone elements into the scaffold material. In this work, Mg-Whitlockite (WH) and Calcium Silicate (CS) were selected as matrix and reinforcement respectively, because of their desirable elemental composition and regenerative properties. The magnesium in WH increases mineralization in bone, and the silicon ions in CS support vascularization. The Mg-WH was synthesized using the wet chemical method, and powder characterization tests were performed. Response surface methodology (RSM) is used to design the experiments with a combination of material compositions, infill ratios (IFs), and sintering temperatures (STs). The WH/CS bioceramic composite is 3D printed in three different compositions: 100/0, 75/25, and 50/50 wt%, with IFs of 50%, 75%, and 100%. The physical and mechanical characterization study of printed samples is conducted and the result is optimized using RSM. ANOVA (Analysis of Variance) is used to establish the relationship between input parameters and responses. The optimized input parameters were the WH/CS composition of 50/50 wt%, IF of 50%, and ST of 1150 °C, which bring out the best possible combination of physical and mechanical characteristics. The RSM optimized response was a density of 2.27 g cm-3, porosity of 36.74%, wettability of 45.79%, shrinkage of 25.13%, compressive strength of 12 MPa, and compressive modulus of 208.49 MPa with 92% desirability. The biological characterization studies were conducted for the scaffold samples prepared with optimized input parameters. The biological studies confirmed the capabilities of the WH/CS composite scaffolds in bone regenerative applications.

Research Progress in 3D Printed Biobased and Biodegradable Polyester/Ceramic Composite Materials: Applications and Challenges in Bone Tissue Engineering

Transplantation of bone implants is currently recognized as one of the most effective means of treating bone defects. Biobased and biodegradable polyester composites combine the good mechanical and degradable properties of polyester, thereby providing an alternative for bone implant materials. Bone tissue engineering (BTE) accelerates bone defect repair by simulating the bone microenvironment. Composite scaffolds support bone formation and further accelerate the process of bone repair. The introduction of 3D printing technology enables the preparation of scaffolds to be more precise, reproducible, and flexible, which is a very promising development. This review presents the physical properties of BTE scaffolds and summarizes the strategies adopted by domestic and international scholars to improve the properties of scaffolds based on biobased and biodegradable polyester/ceramic composites in recent years. In addition, future development prospects in the field and the challenges of expanding production in clinical applications are presented.

Bone Tissue Engineering: From Biomaterials to Clinical Trials

Bone tissue engineering is a promising field that aims to rebuild the bone tissue using biomaterials, cells, and signaling molecules. Materials like natural and synthetic polymers, inorganic materials, and composite materials are used to create scaffolds that mimic the hierarchical microstructure of bone. Stem cells, particularly mesenchymal stem cells (MSCs), play a crucial role in bone tissue engineering by promoting tissue regeneration and modulating the immune response. Growth factors like bone morphogenetic proteins (BMPs), vascular endothelial growth factor (VEGF), and platelet-derived growth factor (PDGF) are utilized to accelerate bone regeneration. Clinical applications include treating nonunion and mal-union fractures, osteonecrosis, orthopedic surgery, dental applications, and spinal cord injuries. Recent advances in the field include nanotechnology, 3D printing, bioprinting techniques, gene editing technologies, and microfluidic devices for drug testing. However, challenges remain, such as standardization of protocols, large-scale biomaterial production, personalized medicine approaches, cost-effectiveness, and regulatory issues. Current clinical trials are investigating the safety and efficacy of various bone tissue engineering approaches, with the potential to modernize patient care by providing more adequate treatments for bone defects and injuries.

A Novel Triad of Bio-Inspired Design, Digital Fabrication, and Bio-Derived Materials for Personalised Bone Repair

The emerging paradigm of personalised bone repair embodies a transformative triad comprising bio-inspired design, digital fabrication, and the exploration of innovative materials. The increasing average age of the population, alongside the rising incidence of fractures associated with age-related conditions such as osteoporosis, necessitates the development of customised, efficient, and minimally invasive treatment modalities as alternatives to conventional methods (e.g., autografts, allografts, Ilizarov distraction, and bone fixators) typically employed to promote bone regeneration. A promising innovative technique involves the use of cellularised scaffolds incorporating mesenchymal stem cells (MSCs). The selection of materials-ranging from metals and ceramics to synthetic or natural bio-derived polymers-combined with a design inspired by natural sources (including bone, corals, algae, shells, silk, and plants) facilitates the replication of geometries, architectures, porosities, biodegradation capabilities, and mechanical properties conducive to physiological bone regeneration. To mimic internal structures and geometries for construct customisation, scaffolds can be designed using Computer-aided Design (CAD) and fabricated via 3D-printing techniques. This approach not only enables precise control over external shapes and internal architectures but also accommodates the use of diverse materials that improve biological performance and provide economic advantages. Finally, advanced numerical models are employed to simulate, analyse, and optimise the complex processes involved in personalised bone regeneration, with computational predictions validated against experimental data and in vivo studies to ascertain the model's ability to predict the recovery of bone shape and function.

Materials for 3D printing in healthcare sector: A review

Additive Manufacturing (AM) encompasses various techniques creating intricate components from digital models. The aim of incorporating 3D printing (3DP) in the healthcare sector is to transform patient care by providing personalized solutions, improving medical procedures, fostering research and development, and ultimately optimizing the efficiency and effectiveness of healthcare delivery. This review delves into the historical beginnings of AM's 9 integration into medical contexts exploring various categories of AM methodologies and their roles within the medical sector. This survey also dives into the issue of material requirements and challenges specific to AM's medical applications. Emphasis is placed on how AM processes directly enhance human well-being. The primary focus of this paper is to highlight the evolution and incentives for cross-disciplinary AM applications, particularly in the realm of healthcare by considering their principle, materials and applications. It is designed for a diverse audience, including manufacturing professionals and researchers, seeking insights into this transformative technology's medical dimensions.

Dual-functional Hydroxyapatite scaffolds for bone regeneration and precision drug delivery

Addressing infected bone defects remains a significant challenge in orthopedics, requiring effective infection control and bone defect repair. A promising therapeutic approach involves the development of dual-functional engineered biomaterials with drug delivery systems that combine antibacterial properties with osteogenesis promotion. The Hydroxyapatite composite scaffolds offer a one-stage treatment, eliminating the need for multiple surgeries and thereby streamlining the process and reducing treatment time. This review delves into the impaired bone repair mechanisms within pathogen-infected and inflamed microenvironments, providing a theoretical foundation for treating infectious bone defects. Additionally, it explores composite scaffolds made of antibacterial and osteogenic materials, along with advanced drug delivery systems that possess both antibacterial and bone-regenerative properties. By offering a comprehensive understanding of the microenvironment of infectious bone defects and innovative design strategies for dual-function scaffolds, this review presents significant advancements in treatment methods for infectious bone defects. Continued research and clinical validation are essential to refine these innovations, ensuring biocompatibility and safety, achieving controlled release and stability, and developing scalable manufacturing processes for widespread clinical application.

Application of gelatin-based composites in bone tissue engineering

Natural bone tissue has the certain function of self-regeneration and repair, but it is difficult to repair large bone damage. Recently, although autologous bone grafting is the "gold standard" for improving bone repair, it has high cost, few donor sources. Besides, allogeneic bone grafting causes greater immune reactions, which hardly meet clinical needs. The bone tissue engineering (BTE) has been developed to promote bone repair. Gelatin, due to its biocompatibility, receives a great deal of attention in the BTE research field. However, the disadvantages of natural gelatin are poor mechanical properties and single structural property. With the development of BTE, gelatin is often used in combination with a range of natural, synthetic polymers, and inorganic materials to achieve synergistic effects for the complex physiological process of bone repair. The review delves into the fundamental structure and unique properties of gelatin, as well as the excellent properties necessary for bone scaffold materials. Then this review explores the application of modified gelatin three-dimensional (3D) scaffolds with various structures in bone repair, including 3D fiber scaffolds, hydrogels, and nanoparticles. In addition, the review focuses on the excellent efficacy of composite bone tissue scaffolds consisting of modified gelatin, various natural or synthetic polymeric materials, as well as bioactive ceramics and inorganic metallic/non-metallic materials in the repair of bone defects. The combination of these gelatin-based composite scaffolds provides new ideas for the design of scaffold materials for bone repair with good biosafety.

Fabrication Strategies for Bioceramic Scaffolds in Bone Tissue Engineering with Generative Design Applications

The aim of this study is to provide an overview of the current state-of-the-art in the fabrication of bioceramic scaffolds for bone tissue engineering, with an emphasis on the use of three-dimensional (3D) technologies coupled with generative design principles. The field of modern medicine has witnessed remarkable advancements and continuous innovation in recent decades, driven by a relentless desire to improve patient outcomes and quality of life. Central to this progress is the field of tissue engineering, which holds immense promise for regenerative medicine applications. Scaffolds are integral to tissue engineering and serve as 3D frameworks that support cell attachment, proliferation, and differentiation. A wide array of materials has been explored for the fabrication of scaffolds, including bioceramics (i.e., hydroxyapatite, beta-tricalcium phosphate, bioglasses) and bioceramic-polymer composites, each offering unique properties and functionalities tailored to specific applications. Several fabrication methods, such as thermal-induced phase separation, electrospinning, freeze-drying, gas foaming, particle leaching/solvent casting, fused deposition modeling, 3D printing, stereolithography and selective laser sintering, will be introduced and thoroughly analyzed and discussed from the point of view of their unique characteristics, which have proven invaluable for obtaining bioceramic scaffolds. Moreover, by highlighting the important role of generative design in scaffold optimization, this review seeks to pave the way for the development of innovative strategies and personalized solutions to address significant gaps in the current literature, mainly related to complex bone defects in bone tissue engineering.

Optimizing Wound Healing: Examining the Influence of Biopolymers Through a Comprehensive Review of Nanohydrogel-Embedded Nanoparticles in Advancing Regenerative Medicine

Nanohydrogel wound healing refers to the use of nanotechnology-based hydrogel materials to promote the healing of wounds. Hydrogel dressings are made up of a three-dimensional network of hydrophilic polymers that can absorb and retain large amounts of water or other fluids. Nanohydrogels take this concept further by incorporating nanoscale particles or structures into the hydrogel matrix. These nanoparticles can be made of various materials, such as silver, zinc oxide, or nanoparticles derived from natural substances like chitosan. The inclusion of nanoparticles can provide additional properties and benefits to the hydrogel dressings. Nanohydrogels can be designed to release bioactive substances, such as growth factors or drugs, in a controlled manner. This allows for targeted delivery of therapeutics to the wound site, promoting healing and reducing inflammation. Nanoparticles can reinforce the structure of hydrogels, improving their mechanical strength and stability. Nanohydrogels often incorporate antimicrobial nanoparticles, such as silver or zinc oxide. These nanoparticles have shown effective antimicrobial activity against a wide range of bacteria, fungi, and other pathogens. By incorporating them into hydrogel dressings, nanohydrogels can help prevent or reduce the risk of infection in wounds. Nanohydrogels can be designed to encapsulate and release bioactive substances, such as growth factors, peptides, or drugs, in a controlled and sustained manner. This targeted delivery of therapeutic agents promotes wound healing by facilitating cell proliferation, reducing inflammation, and supporting tissue regeneration. The unique properties of nanohydrogels, including their ability to maintain a moist environment and deliver bioactive agents, can help accelerate the wound healing process. By creating an optimal environment for cell growth and tissue repair, nanohydrogels can promote faster and more efficient healing of wounds.