3D poly-ε-caprolactone/graphene porous scaffolds for bone tissue engineering

Fabrication of 3D bioactive melt electrowriting composite scaffold with high osteogenic potential

A key challenge in using melt electrowriting (MEW) technology is incorporating large amounts of bioactive inorganic materials, such as hydroxyapatite (HA). In the present study, following optimization of the fabrication parameters, 40 %-HA (HA40) nanoparticles were pre-mixed into medical-grade polycaprolactone (PCL) and processed using the MEW (MEW) technique to mimic the structure and function of the natural extracellular matrix (ECM) for bone regeneration. The HA40 fibrous composite scaffolds showed continuous writing and obtained a well-connected and orderly stacked fibre with a small diameter size (67 ± 8.5 µm). A major result of the present study was the successful enrichment and accumulation of the HA particles, which mostly occurred on the MEW fibre external surfaces. This design allows for direct interfacial interaction with human periodontal ligament cells (hPDLCs). We systematically investigated the behaviour and function of hPDLCs on the HA40 composite scaffold, alongside parameters related to mineralization. The HA40 scaffold demonstrated significantly higher metabolic activity and enhanced expression of osteopontin compared to PCL-only scaffolds, as well as increased levels of ALP and COL1. The study's findings demonstrate that bioactive composite scaffolds, incorporating 40 % HA into m-PCL via MEW, effectively enhance the biological response of the ECM and are promising for potential applications in bone regeneration.

Keratin-containing scaffolds for tissue engineering applications: a review

In tissue engineering and regenerative medicine applications, the utilization of bioactive materials has become a routine tool. The goal of tissue engineering is to create new organs and tissues by combining cell biology, materials science, reactor engineering, and clinical research. As part of the growth pattern for primary cells in an organ, backing material is frequently used as a supporting material. A porous three-dimensional (3D) scaffold can provide cells with optimal conditions for proliferating, migrating, differentiating, and functioning as a framework. Optimizing the scaffolds' structure and altering their surface may improve cell adhesion and proliferation. A keratin-based biomaterials platform has been developed as a result of discoveries made over the past century in the extraction, purification, and characterization of keratin proteins from hair and wool fibers. Biocompatibility, biodegradability, intrinsic biological activity, and cellular binding motifs make keratin an attractive biomaterial for tissue engineering scaffolds. Scaffolds for tissue engineering have been developed from extracted keratin proteins because of their capacity to self-assemble and polymerize into intricate 3D structures. In this review article, applications of keratin-based scaffolds in different tissues including bone, skin, nerve, and vascular are explained based on common methods of fabrication such as electrospinning, freeze-drying process, and sponge replication method.

Advances in additive manufacturing of polycaprolactone based scaffolds for bone regeneration

Critical sized bone defects are difficult to manage and currently available clinical/surgical strategies for treatment are not completely successful. Polycaprolactone (PCL) which is a biodegradable and biocompatible thermoplastic can be 3D printed using medical images into patient specific bone implants. The excellent mechanical properties and low immunogenicity of PCL makes it an ideal biomaterial candidate for 3D printing of bone implants. Though PCL suffers from the limitation of being bio-inert. Here we describe the use of PCL as a biomaterial for 3D printing for bone regeneration, and advances made in the field. The specific focus is on the different 3D printing techniques used for this purpose and various modification that can enhance bone regeneration following the development pathways. We further describe the effect of various scaffold characteristics on bone regeneration both in vitro and the translational assessment of these 3D printed PCL scaffolds in animal studies. The generated knowledge will help understand cell-material interactions of 3D printed PCL scaffolds, to further improve scaffold chemistry and design that can replicate bone developmental processes and can be translated clinically.

Early In Vivo Osteogenic and Inflammatory Response of 3D Printed Polycaprolactone/Carbon Nanotube/Hydroxyapatite/Tricalcium Phosphate Composite Scaffolds

The development of advanced biomaterials and manufacturing processes to fabricate biologically and mechanically appropriate scaffolds for bone tissue is a significant challenge. Polycaprolactone (PCL) is a biocompatible and degradable polymer used in bone tissue engineering, but it lacks biofunctionalization. Bioceramics, such as hydroxyapatite (HA) and β tricalcium phosphate (β-TCP), which are similar chemically to native bone, can facilitate both osteointegration and osteoinduction whilst improving the biomechanics of a scaffold. Carbon nanotubes (CNTs) display exceptional electrical conductivity and mechanical properties. A major limitation is the understanding of how PCL-based scaffolds containing HA, TCP, and CNTs behave in vivo in a bone regeneration model. The objective of this study was to evaluate the use of three-dimensional (3D) printed PCL-based composite scaffolds containing CNTs, HA, and β-TCP during the initial osteogenic and inflammatory response phase in a critical bone defect rat model. Gene expression related to early osteogenesis, the inflammatory phase, and tissue formation was evaluated using quantitative real-time PCR (RT-qPCR). Tissue formation and mineralization were assessed by histomorphometry. The CNT+HA/TCP group presented higher expression of osteogenic genes after seven days. The CNT+HA and CNT+TCP groups stimulated higher gene expression for tissue formation and mineralization, and pro- and anti-inflammatory genes after 14 and 30 days. Moreover, the CNT+TCP and CNT+HA/TCP groups showed higher gene expressions related to M1 macrophages. The association of CNTs with ceramics at 10wt% (CNT+HA/TCP) showed lower expressions of inflammatory genes and higher osteogenic, presenting a positive impact and balanced cell signaling for early bone formation. The association of CNTs with both ceramics promoted a minor inflammatory response and faster bone tissue formation.

Novel Application of 3D Scaffolds of Poly(E-Caprolactone)/Graphene as Osteoinductive Properties in Bone Defect

OBJECTIVE

 Scaffolds provided a surface on which cells could attach, proliferate, and differentiate. Nowadays, bone tissue engineering offers hope for treating bone cancer. Poly(e-caprolactone) (PCL)/graphene have capability as an osteogenic and regenerative therapy. It could be used to produce bone tissue engineering scaffolds. The purpose of this study was to investigate the ability of PCL/graphene to enhance the osteoinductive mechanism.

MATERIALS AND METHODS

 The PCL/graphene scaffold was developed utilizing a particulate-leaching process and cultured with osteoblast-like cells MG63 at 0.5, 1.5, and 2.5 wt% of graphene. We evaluated the porosity, pore size, migratory cells, and cell attachment of the scaffold.

STATISTICAL ANALYSIS

 Data was expressed as the mean ± standard error of the mean and statistical analyses were performed using one-way analysis of variance and Tukey's post hoc at a level of p-value < 0.05.

RESULTS

 Porosity of scaffold with various percentage of graphene was nonsignificant (p > 0.05). There were differences in the acceleration of cell migration following wound closure between groups at 24 hours (p < 0.01) and 48 hours (p < 0.00). Adding the graphene on the scaffolds enhanced migration of osteoblast cells culture and possibility to attach. Graphene on 2.5 wt% exhibited good characteristics over other concentrations.

CONCLUSION

 This finding suggests that PCL/graphene composites may have potential applications in bone tissue engineering.

Recent Advancements in Electrospun Chitin and Chitosan Nanofibers for Bone Tissue Engineering Applications

Treatment of large segmental bone loss caused by fractures, osteomyelitis, and non-union results in expenses of around USD 300,000 per case. Moreover, the worst-case scenario results in amputation in 10% to 14.5% of cases. Biomaterials, cells, and regulatory elements are employed in bone tissue engineering (BTE) to create biosynthetic bone grafts with effective functionalization that can aid in the restoration of such fractured bones, preventing amputation and alleviating expenses. Chitin (CT) and chitosan (CS) are two of the most prevalent natural biopolymers utilized in the fields of biomaterials and BTE. To offer the structural and biochemical cues for augmenting bone formation, CT and CS can be employed alone or in combination with other biomaterials in the form of nanofibers (NFs). When compared with several fabrication methods available to produce scaffolds, electrospinning is regarded as superior since it enables the development of nanostructured scaffolds utilizing biopolymers. Electrospun nanofibers (ENFs) offer unique characteristics, including morphological resemblance to the extracellular matrix, high surface-area-to-volume ratio, permeability, porosity, and stability. This review elaborates on the recent strategies employed utilizing CT and CS ENFs and their biocomposites in BTE. We also summarize their implementation in supporting and delivering an osteogenic response to treat critical bone defects and their perspectives on rejuvenation. The CT- and CS-based ENF composite biomaterials show promise as potential constructions for bone tissue creation.

Graphene-Based Materials in Dental Applications: Antibacterial, Biocompatible, and Bone Regenerative Properties

Graphene-based materials have been shown to have advantageous properties in biomedical and dental applications due to their high mechanical, physiochemical, antibacterial, and stem cell differentiating properties. Although graphene-based materials have displayed appropriate biocompatible properties when used in implant materials for orthopedic applications, little research has been performed to specifically test the biocompatibility of graphene for dental applications. The oral environment, compared to the body, varies greatly and must be considered when evaluating biocompatibility requirements for dental applications. This review will discuss in vitro and in vivo studies that assess graphene's cytotoxicity, antibacterial properties, and cell differentiation ability to evaluate the overall biocompatibility of graphene-based materials for dental applications. Particle shape, size, and concentration were found to be major factors that affected overall biocompatibility of graphene.

Scaffold Fabrication Techniques of Biomaterials for Bone Tissue Engineering: A Critical Review

Bone tissue engineering (BTE) is a promising alternative to repair bone defects using biomaterial scaffolds, cells, and growth factors to attain satisfactory outcomes. This review targets the fabrication of bone scaffolds, such as the conventional and electrohydrodynamic techniques, for the treatment of bone defects as an alternative to autograft, allograft, and xenograft sources. Additionally, the modern approaches to fabricating bone constructs by additive manufacturing, injection molding, microsphere-based sintering, and 4D printing techniques, providing a favorable environment for bone regeneration, function, and viability, are thoroughly discussed. The polymers used, fabrication methods, advantages, and limitations in bone tissue engineering application are also emphasized. This review also provides a future outlook regarding the potential of BTE as well as its possibilities in clinical trials.

Additive Manufactured Poly(ε-caprolactone)-graphene Scaffolds: Lamellar Crystal Orientation, Mechanical Properties and Biological Performance

Understanding the mechano-biological coupling mechanisms of biomaterials for tissue engineering is of major importance to assure proper scaffold performance in situ. Therefore, it is of paramount importance to establish correlations between biomaterials, their processing conditions, and their mechanical behaviour, as well as their biological performance. With this work, it was possible to infer a correlation between the addition of graphene nanoparticles (GPN) in a concentration of 0.25, 0.5, and 0.75% (w/w) (GPN0.25, GPN0.5, and GPN0.75, respectively) in three-dimensional poly(ε-caprolactone) (PCL)-based scaffolds, the extrusion-based processing parameters, and the lamellar crystal orientation through small-angle X-ray scattering experiments of extruded samples of PCL and PCL/GPN. Results revealed a significant impact on the scaffold's mechanical properties to a maximum of 0.5% of GPN content, with a significant improvement in the compressive modulus of 59 MPa to 93 MPa. In vitro cell culture experiments showed the scaffold's ability to support the adhesion and proliferation of L929 fibroblasts (fold increase of 28, 22, 23, and 13 at day 13 (in relation to day 1) for PCL, GPN0.25, GPN0.5, and GPN0.75, respectively) and bone marrow mesenchymal stem/stromal cells (seven-fold increase for all sample groups at day 21 in relation to day 1). Moreover, the cells maintained high viability, regular morphology, and migration capacity in all the different experimental groups, assuring the potential of PCL/GPN scaffolds for tissue engineering (TE) applications.

Comprehensive Review on Design and Manufacturing of Bio-scaffolds for Bone Reconstruction

Bio-scaffolds are synthetic entities widely employed in bone and soft-tissue regeneration applications. These bio-scaffolds are applied to the defect site to provide support and favor cell attachment and growth, thereby enhancing the regeneration of the defective site. The progressive research in bio-scaffold fabrication has led to identification of biocompatible and mechanically stable materials. The difficulties in obtaining grafts and expenditure incurred in the transplantation procedures have also been overcome by the implantation of bio-scaffolds. Drugs, cells, growth factors, and biomolecules can be embedded with bio-scaffolds to provide localized treatments. The right choice of materials and fabrication approaches can help in developing bio-scaffolds with required properties. This review mostly focuses on the available materials and bio-scaffold techniques for bone and soft-tissue regeneration application. The first part of this review gives insight into the various classes of biomaterials involved in bio-scaffold fabrication followed by design and simulation techniques. The latter discusses the various additive, subtractive, hybrid, and other improved techniques involved in the development of bio-scaffolds for bone regeneration applications. Techniques involving multimaterial printing and multidimensional printing have also been briefly discussed.

Advances in Use of Nanomaterials for Musculoskeletal Regeneration

Since the worldwide incidence of bone disorders and cartilage damage has been increasing and traditional therapy has reached its limits, nanomaterials can provide a new strategy in the regeneration of bones and cartilage. The nanoscale modifies the properties of materials, and many of the recently prepared nanocomposites can be used in tissue engineering as scaffolds for the development of biomimetic materials involved in the repair and healing of damaged tissues and organs. In addition, some nanomaterials represent a noteworthy alternative for treatment and alleviating inflammation or infections caused by microbial pathogens. On the other hand, some nanomaterials induce inflammation processes, especially by the generation of reactive oxygen species. Therefore, it is necessary to know and understand their effects in living systems and use surface modifications to prevent these negative effects. This contribution is focused on nanostructured scaffolds, providing a closer structural support approximation to native tissue architecture for cells and regulating cell proliferation, differentiation, and migration, which results in cartilage and bone healing and regeneration.

Biomimetic Graphene/Spongin Scaffolds for Improved Osteoblasts Bioactivity via Dynamic Mechanical Stimulation

Biomimetics offers excellent prospects for design a novel generation of improved biomaterials. Here the controlled integration of graphene oxide (GO) derivatives with a 3D marine spongin (MS) network is explored to nanoengineer novel smart bio-based constructs for bone tissue engineering. The results point out that 3D MS surfaces can be homogeneously coated by layer-by-layer (LbL) assembly of oppositely charged polyethyleneimine (PEI) and GO. Notably, the GOPEI@MS bionanocomposites present a high structural and mechanical stability under compression tests in wet conditions (shape memory). Dynamic mechanically (2 h of sinusoidal compression cyclic interval (0.5 Hz, 0-10% strain)/14 d) stimulates GOPEI@MS seeded with osteoblast (MC3T3-E1), shows a significant improvement in bioactivity, with cell proliferation being two times higher than under static conditions. Besides, the dynamic assays show that GOPEI@MS bionanocomposites are able to act as mechanical stimulus-responsive scaffolds able to resemble physiological bone extracellular matrix (ECM) requirements by strongly triggering mineralization of the bone matrix. These results prove that the environment created by the system cell-GOPEI@MS is suitable for controlling the mechanisms regulating mechanical stimulation-induced cell proliferation for potential in vivo experimentation.

Recent Advances in the Application of Two-Dimensional Nanomaterials for Neural Tissue Engineering and Regeneration

The complexity of the nervous system structure and function, and its slow regeneration rate, makes it more difficult to treat compared to other tissues in the human body when an injury occurs. Moreover, the current therapeutic approaches including the use of autografts, allografts, and pharmacological agents have several drawbacks and can not fully restore nervous system injuries. Recently, nanotechnology and tissue engineering approaches have attracted many researchers to guide tissue regeneration in an effective manner. Owing to their remarkable physicochemical and biological properties, two-dimensional (2D) nanomaterials have been extensively studied in the tissue engineering and regenerative medicine field. The great conductivity of these materials makes them a promising candidate for the development of novel scaffolds for neural tissue engineering application. Moreover, the high loading capacity of 2D nanomaterials also has attracted many researchers to utilize them as a drug/gene delivery method to treat various devastating nervous system disorders. This review will first introduce the fundamental physicochemical properties of 2D nanomaterials used in biomedicine and the supporting biological properties of 2D nanomaterials for inducing neuroregeneration, including their biocompatibility on neural cells, the ability to promote the neural differentiation of stem cells, and their immunomodulatory properties which are beneficial for alleviating chronic inflammation at the site of the nervous system injury. It also discusses various types of 2D nanomaterials-based scaffolds for neural tissue engineering applications. Then, the latest progress on the use of 2D nanomaterials for nervous system disorder treatment is summarized. Finally, a discussion of the challenges and prospects of 2D nanomaterials-based applications in neural tissue engineering is provided.

Effect of poly (lactic acid) porous membrane prepared via phase inversion induced by water droplets on 3T3 cell behavior

Phase inversion induced by water droplets has garnered attention in the field of polymer science as a novel method for preparing porous membranes. This study investigates the effect of the porous structure of poly (lactic acid) (PLA) membranes prepared through phase inversion induced by water droplets at four different temperatures (25, 50, 75, and 100 °C) on the morphology and proliferation of 3T3 cells. The surface properties of the PLA porous membrane, including pore size, pore size distribution, surface roughness, surface hydrophilicity, and cytocompatibility with 3T3 cells, were evaluated. The results indicated that the synthesized PLA membrane had two surfaces with different structures. The upper surface in contact with the water droplets during preparation contained uniformly distributed micropores, whereas the bottom surface was smooth and composed of small particles in contacted with the mold. The upper surface showed high cytocompatibility with 3T3 cells, and the 3T3 cells migrated and grew within the pores at 25 °C. In contrast, the bottom surface exhibited low biocompatibility with the 3T3 cells. Our study has wide-ranging implications and will improve the fabrication and implementation of 3D cultured scaffolds with excellent cytocompatibility.