Mussel-inspired graphene oxide nanosheet-enwrapped Ti scaffolds with drug-encapsulated gelatin microspheres for bone regeneration

Polydopamine-Based Biomaterials in Orthopedic Therapeutics: Properties, Applications, and Future Perspectives

Polydopamine is a versatile and modifiable polymer, known for its excellent biocompatibility and adhesiveness. It can also be engineered into a variety of nanoparticles and biomaterials for drug delivery, functional modification, making it an excellent choice to enhance the prevention and treatment of orthopedic diseases. Currently, the application of polydopamine biomaterials in orthopedic disease prevention and treatment is in its early stages, despite some initial achievements. This article aims to review these applications to encourage further development of polydopamine for orthopedic therapeutic needs. We detail the properties of polydopamine and its biomaterial types, highlighting its superior performance in functional modification on nanoparticles and materials. Additionally, we also explore the challenges and future prospects in developing optimal polydopamine biomaterials for clinical use in orthopedic disease prevention and treatment.

Growth factor-functionalized titanium implants for enhanced bone regeneration: A review

Titanium and titanium alloys are widely favored materials for orthopedic implants due to their exceptional mechanical properties and biological inertness. The additional benefit of sustained local release of bioactive substances further promotes bone tissue formation, thereby augmenting the osseointegration capacity of titanium implants and attracting increasing attention in bone tissue engineering. Among these bioactive substances, growth factors have shown remarkable osteogenic and angiogenic induction capabilities. Consequently, researchers have developed various physical, chemical, and biological loading techniques to incorporate growth factors into titanium implants, ensuring controlled release kinetics. In contrast to conventional treatment modalities, the localized release of growth factors from functionalized titanium implants not only enhances osseointegration but also reduces the risk of complications. This review provides a comprehensive examination of the types and mechanisms of growth factors, along with a detailed exploration of the methodologies used to load growth factors onto the surface of titanium implants. Moreover, it highlights recent advancements in the application of growth factors to the surface of titanium implants (Scheme 1). Finally, the review discusses current limitations and future prospects for growth factor-functionalized titanium implants. In summary, this paper presents cutting-edge design strategies aimed at enhancing the bone regenerative capacity of growth factor-functionalized titanium implants-a significant advancement in the field of enhanced bone regeneration.

Engineered Metallic Ion-Based Hydrogel for Tendon-Bone Reconstruction

Rotator cuff regeneration is hindered by compromised vascular architecture, inflammation, and instability of the reconstructed tendon-bone interface. Herein, inspired by the phenomenon of magnetic clasps being connected together by a specific structure, an engineered metallic ion-based hydrogel scaffold was constructed through a bioorthogonal click reaction between (DOPA)4-PEG5-N3 and DBCO-BMP-2 peptides and a photopolymerization process in the hydrogel matrix, exhibiting the potential for angiogenesis, bone regeneration, and modulation of the inflammatory milieu, which aimed at facilitating rotator cuff regeneration. In vitro studies showed that the composite hydrogel scaffold stimulated the angiogenic activity of human umbilical vein endothelial cells and osteogenic differentiation of bone marrow mesenchymal stem cells, transforming macrophages from M1 to M2. Moreover, imaging and immunohistochemical analysis of a rat rotator cuff injury models demonstrated that the composite hydrogel could effectively promote regeneration and exhibit remarkable biocompatibility. In summary, this composite hydrogel material established an effective platform for the release of metal ions and clickable peptides, which accelerated the regeneration of rotator cuff injuries and had broad prospects for application in rotator cuff therapy.

Bio-inspired nanocomposite coatings on orthodontic archwires with corrosion resistant and antibacterial properties

The corrosion resistance and antibacterial properties of fixed orthodontic devices are insufficient in the complex oral cavity, which delays tooth movement and causes enamel demineralization. To overcome the challenges, this research constructs a series of polydopamine-graphene oxide (PDA-GO) nanocoatings on representative NiTi archwires via self-assembly. The morphology, chemical structure, and multifunctional properties of coatings showed tunability dependent on the PDA/GO ratio. Optimized PDA-GO coatings with uniform and dense characteristics prolonged the diffusion path for the corrosive medium and reduced Ni dissolution in NiTi alloys. Meanwhile, the applied coatings endowed NiTi alloys with antibacterial activity against Streptococcus mutans due to the surface structures and inherent properties of PDA-GO. In vitro cytotoxicity tests further verified their good biocompatibility. This bio-inspired nanocomposite coating provides a practical reference for modification of dental metal surfaces to better behave in the intraoral environment.

Can Graphene Pave the Way to Successful Periodontal and Dental Prosthetic Treatments? A Narrative Review

Graphene, as a promising material, holds the potential to significantly enhance the field of dental practices. Incorporating graphene into dental materials imparts enhanced strength and durability, while graphene-based nanocomposites offer the prospect of innovative solutions such as antimicrobial dental implants or scaffolds. Ongoing research into graphene-based dental adhesives and composites also suggests their capacity to improve the quality and reliability of dental restorations. This narrative review aims to provide an up-to-date overview of the application of graphene derivatives in the dental domain, with a particular focus on their application in prosthodontics and periodontics. It is important to acknowledge that further research and development are imperative to fully explore the potential of graphene and ensure its safe use in dental practices.

Graphene and its derivatives: "one stone, three birds" strategy for orthopedic implant-associated infections

Orthopedic implants provide an avascular surface for microbial attachment and biofilm formation, impeding the entry of immune cells and the diffusion of antibiotics. The above is an important cause of dental and orthopedic implant-associated infection (IAI). For the prevention and treatment of IAI, the drawbacks of antibiotic resistance and surgical treatment are increasingly apparent. Due to their outstanding biological properties such as biocompatibility, immunomodulatory effects, and antibacterial properties, graphene-based nanomaterials (GBNs) have been applied to bone tissue engineering to deal with IAI, and in particular have great potential application in drug/gene carriers, multi-functional platforms, and coating forms. Here we review the latest research progress and achievements in GBNs for the prevention and treatment of IAI, mainly including their biomedical applications for antibacterial and immunomodulation effects, and for inducing osteogenesis. Furthermore, the biosafety of graphene family materials in bone tissue regeneration and the feasibility of clinical application are critically analyzed and discussed.

Advancements and Utilizations of Scaffolds in Tissue Engineering and Drug Delivery

The drug development process requires a thorough understanding of the scaffold and its three-dimensional structure. Scaffolding is a technique for tissue engineering and the formation of contemporary functioning tissues. Tissue engineering is sometimes referred to as regenerative medicine. They also ensure that drugs are delivered with precision. Information regarding scaffolding techniques, scaffolding kinds, and other relevant facts, such as 3D nanostructuring, are discussed in depth in this literature. They are specific and demonstrate localized action for a specific reason. Scaffold's acquisition nature and flexibility make it a new drug delivery technology with good availability and structural parameter management.

Dual-functional composite scaffolds for inhibiting infection and promoting bone regeneration

The treatment of infected bone defects is an intractable problem in orthopedics. It comprises two critical parts, namely that of infection control and bone defect repair. According to these two core tasks during treatment, the ideal approach of simultaneously controlling infection and repairing bone defects is promising treatment strategy. Several engineered biomaterials and drug delivery systems with dual functions of anti-bacterial action and ostogenesis-promotion have been developed and demonstrated excellent therapeutic effects. Compared with the conventional treatment method, the dual-functional composite scaffold can provide one-stage treatment avoiding multiple surgeries, thereby remarkably simplifying the treatment process and reducing the treatment time, overcoming the disadvantages of conventional bone transplantation. In this review, the impaired bone repair ability and its specific mechanisms in the microenvironment of pathogen infection and excessive inflammation were analyzed, providing a theoretical basis for the treatment of infectious bone defects. Furthermore, we discussed the composite dual-functional scaffold composed of a combination of antibacterial and osteogenic material. Finally, a series of advanced drug delivery systems with antibacterial and bone-promoting capabilities were summarized and discussed. This review provides a comprehensive understanding for the microenvironment of infectious bone defects and leading-edge design strategies for the antibacterial and bone-promoting dual-function scaffold, thus providing clinically significant treatment methods for infectious bone defects.

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Antibacterial and bone-promoting dual-function scaffolds are ideal strategies for treatment of infectious bone defects.

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The effect of infection on bone repair was summarized in detail from four important aspects.

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A variety of dual-function scaffolds based on antibacterial and osteogenic materials were discussed.

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Dual-function drug delivery systems promoting repair of infectious bone defects by locally releasing functional agents.

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Leading-edge design strategies, challenges and prospects for dual-functional biomaterials were provided.

Mussel-Inspired Polydopamine-Based Multilayered Coatings for Enhanced Bone Formation

Repairing bone defects remains a challenge in clinical practice and the application of artificial scaffolds can enhance local bone formation, but the function of unmodified scaffolds is limited. Considering different application scenarios, the scaffolds should be multifunctionalized to meet specific demands. Inspired by the superior adhesive property of mussels, polydopamine (PDA) has attracted extensive attention due to its universal capacity to assemble on all biomaterials and promote further adsorption of multiple external components to form PDA-based multilayered coatings with multifunctional property, which can induce synergistic enhancement of new bone formation, such as immunomodulation, angiogenesis, antibiosis and antitumor property. This review will summarize mussel-inspired PDA-based multilayered coatings for enhanced bone formation, including formation mechanism and biofunction of PDA coating, as well as different functional components. The synergistic enhancement of multiple functions for better bone formation will also be discussed. This review will inspire the design and fabrication of PDA-based multilayered coatings for different application scenarios and promote deeper understanding of their effect on bone formation, but more efforts should be made to achieve clinical translation. On this basis, we present a critical conclusion, and forecast the prospects of PDA-based multilayered coatings for bone regeneration.

Advanced Surface Modification for 3D-Printed Titanium Alloy Implant Interface Functionalization

With the development of three-dimensional (3D) printed technology, 3D printed alloy implants, especially titanium alloy, play a critical role in biomedical fields such as orthopedics and dentistry. However, untreated titanium alloy implants always possess a bioinert surface that prevents the interface osseointegration, which is necessary to perform surface modification to enhance its biological functions. In this article, we discuss the principles and processes of chemical, physical, and biological surface modification technologies on 3D printed titanium alloy implants in detail. Furthermore, the challenges on antibacterial, osteogenesis, and mechanical properties of 3D-printed titanium alloy implants by surface modification are summarized. Future research studies, including the combination of multiple modification technologies or the coordination of the structure and composition of the composite coating are also present. This review provides leading-edge functionalization strategies of the 3D printed titanium alloy implants.

Controlled Release of Molecular Intercalants from Two-Dimensional Nanosheet Films

Solution co-deposition of two-dimensional (2D) nanosheets with chemical solutes yields nanosheet-molecular heterostructures. A feature of these macroscopic layered hybrids is their ability to release the intercalated molecular agent to express chemical functionality on their surfaces or in their near surroundings. Systematic design methods are needed to control this molecular release to match the demand for rate and lifetime in specific applications. We hypothesize that release kinetics are controlled by transport processes within the layered solids, which primarily involve confined molecular diffusion through nanochannels formed by intersheet van der Waals gaps. Here a variety of graphene oxide (GO)/molecular hybrids are fabricated and subject to transient experiments to characterize release kinetics, locations, and mechanisms. The measured release rate profiles can be successfully described by a numerical model of internal transport processes, and the results used to extract effective Z-directional diffusion coefficients for various film types. The diffusion coefficients are found to be 8 orders of magnitude lower than those in free solution due to nanochannel confinement and serpentine path effects, and this retardation underlies the ability of 2D materials to control and extend release over useful time scales. In-plane texturing of the heterostructured films by compressive wrinkling or crumpling is shown to be a useful design tool to control the release rate for a given film type and molecular intercalant. The potential of this approach is demonstrated through case studies on the controlled release of chemical virucidal agents.

Carbon nanotube-reinforced cell-derived matrix-silk fibroin hierarchical scaffolds for bone tissue engineering applications

In bone tissue engineering, the development of advanced biomimetic scaffolds has led to the quest for biomotifs in scaffold design that better recreate the bone matrix structure and composition and hierarchy at different length scales. In this study, an advanced hierarchical scaffold consisting of silk fibroin combined with a decellularized cell-derived extracellular matrix and reinforced with carbon nanotubes was developed. The goal of the carbon nanotube-reinforced cell-derived matrix-silk fibroin hierarchical scaffolds is to harvest the individual properties of their constituents to introduce hierarchical capacity in order to improve standard silk fibroin scaffolds. The scaffolds were fabricated using enzymatic cross-linking, freeze modeling, and decellularization methods. The developed scaffolds were assessed for the pore structure and mechanical properties showing satisfying results to be used in bone regeneration. The developed carbon nanotube-reinforced cell-derived matrix-silk fibroin hierarchical scaffolds were shown to be bioactive in vitro and expressed no hemolytic effect. Furthermore, cellular in vitro studies on human adipose-derived stem cells (hASCs) showed that scaffolds supported cell proliferation. The hASCs seeded onto these scaffolds evidenced similar metabolic activity to standard silk fibroin scaffolds but increased ALP activity. The histological staining showed cell infiltration into the scaffolds and visible collagen production. The expression of several osteogenic markers was investigated, further supporting the osteogenic potential of the developed carbon nanotube-reinforced cell-derived matrix-silk fibroin hierarchical scaffolds. The hemolytic assay demonstrated the hemocompatibility of the hierarchical scaffolds. Overall, the carbon nanotube-reinforced cell-derived matrix-silk fibroin hierarchical scaffolds presented the required architecture for bone tissue engineering applications.

Surface functionalized bioceramics coated on metallic implants for biomedical and anticorrosion performance - a review

In modern days, the usage of trauma fixation devices has significantly increased due to sports injury, age-related issues, accidents, and revision surgery purposes. Numerous materials such as stainless steel, titanium, Co-Cr alloy, polymers, and ceramics have been used to replace the missing or defective parts of the human body. After implantation, body fluids (Na⁺, K⁺, and Cl^-), protein, and blood cells interact with the surface of metallic implants, which favours the release of ions from the metallic surface to surrounding body tissues, leading to a hypersensitive reaction. Body pH, temperature, and interaction of immune cells also cause metal ion leaching and lose host cell interaction and effective mineralization for better durability. Moreover, microbial invasion is another important crisis, which produces extracellular compounds onto the biomaterial surface through which it escapes from the antimicrobial agents. To enhance the performance of materials by improving mechanical, corrosion resistance, antimicrobial, and biocompatibility properties, surface modification is a prerequisite method in which chemical vapour deposition (CVD), physical vapour deposition (PVD), sol-gel method, and electrochemical deposition are generally involved. The properties of bioceramics such as chemical inertness, bioactivity, biocompatibility, and corrosion protection make them most suitable for the surface functionalization of metallic implants. To the best of our knowledge, very limited literature is available to discuss the interaction of body proteins, pH, and temperature onto bioceramic coatings. Hence, the present review focuses on the corrosion behaviour of different ceramic composite coating materials with different conditions. This review initially briefs the properties and surface chemistry of metal implants and the need for surface modifications by different deposition techniques. Further, mechanical, cytotoxicity, antimicrobial property, and electrochemical behaviour of ceramics and metal nitride coatings are discussed. Finally, future perspectives of coatings are outlined for biomedical applications.

Graphene and its Derivatives for Bone Tissue Engineering: In Vitro and In Vivo Evaluation of Graphene-Based Scaffolds, Membranes and Coatings

Bone regeneration or replacement has been proved to be one of the most effective methods available for the treatment of bone defects caused by different musculoskeletal disorders. However, the great contradiction between the large demand for clinical therapies and the insufficiency and deficiency of natural bone grafts has led to an urgent need for the development of synthetic bone graft substitutes. Bone tissue engineering has shown great potential in the construction of desired bone grafts, despite the many challenges that remain to be faced before safe and reliable clinical applications can be achieved. Graphene, with outstanding physical, chemical and biological properties, is considered a highly promising material for ideal bone regeneration and has attracted broad attention. In this review, we provide an introduction to the properties of graphene and its derivatives. In addition, based on the analysis of bone regeneration processes, interesting findings of graphene-based materials in bone regenerative medicine are analyzed, with special emphasis on their applications as scaffolds, membranes, and coatings in bone tissue engineering. Finally, the advantages, challenges, and future prospects of their application in bone regenerative medicine are discussed.

Performance of the Polydopamine-Graphene Oxide Composite Substrate in the Osteogenic Differentiation of Mouse Embryonic Stem Cells

Graphene oxide (GO) is a biocompatible material considered a favorable stem cell culture substrate. In this study, GO was modified with polydopamine (PDA) to facilitate depositing GO onto a tissue culture polystyrene (PT) surface, and the osteogenic performance of the PDA/GO composite in pluripotent embryonic stem cells (ESCs) was investigated. The surface chemistry of the PDA/GO-coated PT surface was analyzed by scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). A high cell viability of ESCs cultured on the PDA/GO composite-coated surface was initially ensured. Then, the osteogenic differentiation of the ESCs in response to the PDA/GO substrate was assessed by alkaline phosphatase (ALP) activity, intracellular calcium levels, matrix mineralization assay, and evaluation of the mRNA and protein levels of osteogenic factors. The culture of ESCs on the PDA/GO substrate presented higher osteogenic potency than that on the uncoated control surface. ESCs cultured on the PDA/GO substrate expressed significantly higher levels of integrin α5 and β1, as well as bone morphogenetic protein receptor (BMPR) types I and II, compared with the control groups. The phosphorylation of extracellular signal-regulated kinase (ERK)1/2, p38, and c-Jun-N-terminal kinase (JNK) mitogen-activated protein kinases (MAPKs) was observed in ESCs culture on the PDA/GO substrate. Moreover, BMP signal transduction by SMAD1/5/8 phosphorylation was increased more in cells on PDA/GO than in the control. The nuclear translocation of SMAD1/5/8 in cells was also processed in response to the PDA/GO substrate. Blocking activation of the integrin α5/β1, MAPK, or SMAD signaling pathways downregulated the PDA/GO-induced osteogenic differentiation of ESCs. These results suggest that the PDA/GO composite stimulates the osteogenic differentiation of ESCs via the integrin α5/β1, MAPK, and BMPR/SMAD signaling pathways.

Progress of gelatin-based microspheres (GMSs) as delivery vehicles of drug and cell

Gelatin has various attractive features as biomedical materials, for instance, biocompatibility, low immunogenicity, biodegradability, and ease of manipulation. In recent years, various gelatin-based microspheres (GMSs) have been fabricated with innovative technologies to serve as sustained delivery vehicles of drugs and genetic materials as well as beneficial bacteria. Moreover, GMSs have exhibited promising potentials to act as both cell carriers and 3D scaffold components in tissue engineering and regenerative medicine, which not only exhibit excellent injectability but also could be integrated into a macroscale construct with the laden cells. Herein, we aim to thoroughly summarize the recent progress in the preparations and biomedical applications of GMSs and then to point out the research direction in future. First, various methods for the fabrication of GMSs will be described. Second, the recent use of GMSs in tumor embolization and in the delivery of cells, drugs, and genetic material as well as bacteria will be presented. Finally, several key factors that may enhance the improvement of GMSs were suggested as delivery vehicles.

Graphene-Based Biomaterials for Bone Regenerative Engineering: A Comprehensive Review of the Field and Considerations Regarding Biocompatibility and Biodegradation

Graphene and its derivatives have continued to garner worldwide interest due to their unique characteristics. Having expanded into biomedical applications, there have been efforts to employ their exceptional properties for the regeneration of different tissues, particularly bone. This article presents a comprehensive review on the usage of graphene-based materials for bone regenerative engineering. The graphene family of materials (GFMs) are used either alone or in combination with other biomaterials in the form of fillers in composites, coatings for both scaffolds and implants, or vehicles for the delivery of various signaling and therapeutic agents. The applications of the GFMs in each of these diverse areas are discussed and emphasis is placed on the characteristics of the GFMs that have implications in this regard. In tandem and of importance, this article evaluates the safety and biocompatibility of the GFMs and carefully elucidates how various factors influence the biocompatibility and biodegradability of this new class of nanomaterials. In conclusion, the challenges and opportunities regarding the use of the GFMs in regenerative engineering applications are discussed, and future perspectives for the developments in this field are proposed.

Biomaterials against Bone Infection

Chronic bone infection is considered as one of the most problematic biofilm-related infections. Its recurrent and resistant nature, high morbidity, prolonged hospitalization, and costly medical care expenses have driven the efforts of the scientific community to develop new therapies to improve the standards used today. There is great debate on the management of this kind of infection in order to establish consistent and agreed guidelines in national health systems. The scientific research is oriented toward the design of anti-infective biomaterials both for prevention and cure. The properties of these materials must be adapted to achieve better anti-infective performance and good compatibility, which allow a good integration of the implant with the surrounding tissue. The objective of this review is to study in-depth the antibacterial biomaterials and the strategies underlying them. In this sense, this manuscript focuses on antimicrobial coatings, including the new technological advances on surface modification; scaffolding design including multifunctional scaffolds with both antimicrobial and bone regeneration properties; and nanocarriers based on mesoporous silica nanoparticles with advanced properties (targeting and stimuli-response capabilities).

Mussel-inspired polydopamine induced the osteoinductivity to ice-templating PLGA-gelatin matrix for bone tissue engineering application

In this study, poly(lactic-co-glycolic acid) (PLGA)-gelatin scaffolds were fabricated using the freeze-casting technique. Polydopamine (PDA) coating was applied on the surface of scaffolds to enhance the hydrophilicity, bioactivity, and cellular behavior of the composite constructs. Further, the synergistic effect of PDA coating and lamellar microstructure of scaffolds was evaluated on the promotion of properties. Based on morphological observations, freeze-casting constructs showed lamellar pore channels while the uniformity and pore size were slightly affected by deposition of PDA. The hydrophilicity and swelling capacity of the scaffolds were assessed using contact angle measurement and phosphate buffered saline absorption ratio. The results indicated a significant increment in water-matrix interactions following surface modification. The evaluation of the biodegradation ratio revealed the higher degree of degradation in PDA-coated samples owing to the presence of hydrophilic functional groups in the chemical structure of PDA. On the other hand, the bioactivity potential of PDA in the simulated body fluid solution confirmed the possibility of using coated constructs as a bone reconstructive substitute. The improvement of cellular attachment and filopodia formation in PDA-contained matrixes was the other benefit of the coating process. Furthermore, cellular proliferation and ALP activity were enhanced after PDA coating. The suggested PDA-coated PLGA-gelatin scaffolds can be applied in bone tissue regeneration.

Three-Dimensional High-Porosity Chitosan/Honeycomb Porous Carbon/Hydroxyapatite Scaffold with Enhanced Osteoinductivity for Bone Regeneration

Three-dimensional honeycomb porous carbon (HPC) has attracted increasing attention in bioengineering due to excellent mechanical properties and a high surface-to-volume ratio. In this paper, a three-dimensional chitosan (CS)/honeycomb porous carbon/hydroxyapatite composite was prepared by nano-sized hydroxyapatite (nHA) on the HPC surface in situ deposition, dissolved in chitosan solution, and vacuum freeze-dried. The structure and composition of CS/HPC/nHA were characterized by scanning electron microscopy, transmission electron miscroscopy, Fourier transform infrared, and X-ray photoelectron spectroscopy, and the porosity, swelling ratio, and mechanical properties of the scaffold were also tested. The as-prepared scaffolds possess hierarchical pores and organic-inorganic components, which are similar in composition and structure to bone tissues. The synthesized composite scaffold has high porosity and a certain mechanical strength. By culturing mouse bone marrow mesenchymal stem cells on the surface of the scaffold, it was confirmed that the scaffold facilitated its growth and promoted its differentiation into the osteogenesis direction. In vivo experiments further demonstrate that the CS/HPC/nHA composite scaffold has a significant advantage in promoting bone formation in the bone defect area. All the results suggested that the CS/HPC/nHA scaffolds have great application prospect in bone tissue engineering.

Do biomedical engineers dream of graphene sheets?

During the past few years, graphene has outstandingly emerged as a key nanomaterial for boosting the performance of commercial, industrial and scientific related technologies. The popularity of this novel nanomaterial in biomedical engineering is due to its excellent biological, electronic, optical and thermal properties that, as a whole, surpass the features of commonly used biomaterials and consequently open a wide range of applications so far within the reach of science fiction. In this minireview, the potential of graphene and its based materials in the expanding biomedical field is highlighted with focus on groundbreaking diagnostic, monitoring and therapeutic strategies. Some of the major challenges related to the synthesis and safety of graphene-based materials are also briefly discussed because of their critical importance in bringing this class of carbon materials closer to the clinic.

Graphene-based 3D scaffolds in tissue engineering: fabrication, applications, and future scope in liver tissue engineering

Tissue engineering embraces the potential of recreating and replacing defective body parts by advancements in the medical field. Being a biocompatible nanomaterial with outstanding physical, chemical, optical, and biological properties, graphene-based materials were successfully employed in creating the perfect scaffold for a range of organs, starting from the skin through to the brain. Investigations on 2D and 3D tissue culture scaffolds incorporated with graphene or its derivatives have revealed the capability of this carbon material in mimicking in vivo environment. The porous morphology, great surface area, selective permeability of gases, excellent mechanical strength, good thermal and electrical conductivity, good optical properties, and biodegradability enable graphene materials to be the best component for scaffold engineering. Along with the apt microenvironment, this material was found to be efficient in differentiating stem cells into specific cell types. Furthermore, the scope of graphene nanomaterials in liver tissue engineering as a promising biomaterial is also discussed. This review critically looks into the unlimited potential of graphene-based nanomaterials in future tissue engineering and regenerative therapy.

Advances in materials for cellular applications (Review)

The goal of this review is to highlight materials that show exciting promise for either entirely new cellular-level applications or new approaches to long-standing biological challenges. The authors start with two more established materials, graphene and carbon nanotubes, and then progress to conducting polymers, followed by an overview of the microresonators, nanowires, and spasers used as intracellular lasers. These materials provide new approaches to gene and drug delivery, cellular regeneration, mechanical sensing, imaging, and the modulation and recording of cellular activity. Of specific interest is the comparison of these materials with existing technologies, the method of cellular delivery, and the all-encompassing challenge of biocompatibility. Concluding remarks examine the extension of these materials from cellular-level experiments to in vivo applications, including the method of activation: light, electricity, and ultrasound. Overall, these materials and their associated applications illustrate the most recent advances in material-cell interactions.

3D Printing of Silk Fibroin for Biomedical Applications

Three-dimensional (3D) printing is regarded as a critical technological-evolution in material engineering, especially for customized biomedicine. However, a big challenge that hinders the 3D printing technique applied in biomedical field is applicable bioink. Silk fibroin (SF) is used as a biomaterial for decades due to its remarkable high machinability and good biocompatibility and biodegradability, which provides a possible alternate of bioink for 3D printing. In this review, we summarize the requirements, characteristics and processabilities of SF bioink, in particular, focusing on the printing possibilities and capabilities of bioink. Further, the current achievements of cell-loading SF based bioinks were comprehensively viewed from their physical properties, chemical components, and bioactivities as well. Finally, the emerging issues and prospects of SF based bioink for 3D printing are given. This review provides a reference for the programmable and multiple processes and the further improvement of silk-based biomaterials fabrication by 3D printing.

Enhanced bone regeneration of the silk fibroin electrospun scaffolds through the modification of the graphene oxide functionalized by BMP-2 peptide

Introduction

Bone tissue engineering has become one of the most effective methods to treat bone defects. Silk fibroin (SF) is a natural protein with no physiological activities, which has features such as good biocompatibility and easy processing and causes minimal inflammatory reactions in the body. Scaffolds prepared by electrospinning SF can be used in bone tissue regeneration and repair. Graphene oxide (GO) is rich in functional groups, has good biocompatibility, and promotes osteogenic differentiation of stem cells, while bone morphogenetic protein-2 (BMP-2) polypeptide has an advantage in promoting osteogenesis induction. In this study, we attempted to graft BMP-2 polypeptide onto GO and then bonded the functionalized GO onto SF electrospun scaffolds through electrostatic interactions. The main purpose of this study was to further improve the biocompatibility of SF electrospun scaffolds, which could promote the osteogenic differentiation of bone marrow mesenchymal stem cells and the repair of bone tissue defects.

Materials and methods

The successful synthesis of GO and functionalized GO was confirmed by transmission electron microscope, X-ray photoelectron spectroscopy, and thermogravimetric analysis. Scanning electron microscopy, atomic force microscopy, mechanical test, and degradation experiment confirmed the preparation of SF electrospun scaffolds and the immobilization of GO on the fibers. In vitro experiment was used to verify the biocompatibility of the composite scaffolds, and in vivo experiment was used to prove the repairing ability of the composite scaffolds for bone defects.

Results

We successfully fabricated the composite scaffolds, which enhanced biocompatibility, not only promoting cell adhesion and proliferation but also greatly enhancing in vitro osteogenic differentiation of bone marrow stromal cells using either an osteogenic or non-osteogenic medium. Furthermore, transplantation of the composite scaffolds significantly promoted in vivo bone formation in critical-sized calvarial bone defects.

Conclusion

These findings suggested that the incorporation of BMP-2 polypeptide-functionalized GO into chitosan-coated SF electrospun scaffolds was a viable strategy for fabricating excellent scaffolds that enhance the regeneration of bone defects.

In situ bone regeneration enabled by a biodegradable hybrid double-network hydrogel

The biodegradable hybrid double-network hydrogel for stem cell-enhanced bone regeneration.

Graphene Family Materials in Bone Tissue Regeneration: Perspectives and Challenges

We have witnessed abundant breakthroughs in research on the bio-applications of graphene family materials in current years. Owing to their nanoscale size, large specific surface area, photoluminescence properties, and antibacterial activity, graphene family materials possess huge potential for bone tissue engineering, drug/gene delivery, and biological sensing/imaging applications. In this review, we retrospect recent progress and achievements in graphene research, as well as critically analyze and discuss the bio-safety and feasibility of various biomedical applications of graphene family materials for bone tissue regeneration.

Development of a Graphene Oxide-Incorporated Polydimethylsiloxane Membrane with Hexagonal Micropillars

Several efforts have been made on the development of bioscaffolds including the polydimethylsiloxane (PDMS) elastomer for supporting cell growth into stable sheets. However, PDMS has several disadvantages, such as intrinsic surface hydrophobicity and mechanical strength. Herein, we generated a novel PDMS-based biomimetic membrane by sequential modifications of the PMDS elastomer with graphene oxide (GO) and addition of a hexagonal micropillar structure at the bottom of the biomembrane. GO was initially homogenously mixed with pure PDMS and then was further coated onto the upper surface of the resultant PDMS. The elastic modulus and hydrophilicity were significantly improved by such modifications. In addition, the development of hexagonal micropillars with smaller diameters largely improved the ion permeability and increased the motion resistance. We further cultured retinal pigment epithelial (RPE) cells on the surface of this modified PDMS biomembrane and assayed its biocompatibility. Remarkably, the GO incorporation and coating exhibited beneficial effect on the cell growth and the new formation of tight junctions in RPE cells. Taken together, this GO-modified PDMS scaffold with polyhexagonal micropillars may be utilized as an ideal cell sheet and adaptor for cell cultivation and can be used in vivo for the transplantation of cells such as RPE cells.