Synergistic Effects on Incorporation of β-Tricalcium Phosphate and Graphene Oxide Nanoparticles to Silk Fibroin/Soy Protein Isolate Scaffolds for Bone Tissue Engineering

A Comprehensive Review of Nanoparticles: From Classification to Application and Toxicity

Nanoparticles are structures that possess unique properties with high surface area-to-volume ratio. Their small size, up to 100 nm, and potential for surface modifications have enabled their use in a wide range of applications. Various factors influence the properties and applications of NPs, including the synthesis method and physical attributes such as size and shape. Additionally, the materials used in the synthesis of NPs are primary determinants of their application. Based on the chosen material, NPs are generally classified into three categories: organic, inorganic, and carbon-based. These categories include a variety of materials, such as proteins, polymers, metal ions, lipids and derivatives, magnetic minerals, and so on. Each material possesses unique attributes that influence the activity and application of the NPs. Consequently, certain NPs are typically used in particular areas because they possess higher efficiency along with tenable toxicity. Therefore, the classification and the base material in the NP synthesis hold significant importance in both NP research and application. In this paper, we discuss these classifications, exemplify most of the major materials, and categorize them according to their preferred area of application. This review provides an overall review of the materials, including their application, and toxicity.

Silk-Based 3D Porous Scaffolds for Tissue Engineering

Silk fibroin, extracted from the silk of the Bombyx mori silkworm, stands out as a biomaterial due to its nontoxic nature, excellent biocompatibility, and adjustable biodegradability. Porous scaffolds, a type of biomaterial, are crucial for creating an optimal microenvironment that supports cell adhesion and proliferation, thereby playing an essential role in tissue remodeling and repair. Therefore, this review focuses on 3D porous silk fibroin-based scaffolds, first summarizing their preparation methods and then detailing their regenerative effects on bone, cartilage, tendon, vascular, neural, skin, hepatic, and tracheal epithelial tissue engineering in recent years.

The Future of Graphene: Preparation from Biomass Waste and Sports Applications

At present, the main raw material for producing graphene is graphite ore. However, researchers actively seek alternative resources due to their high cost and environmental problems. Biomass waste has attracted much attention due to its carbon-rich structure and renewability, emerging as a potential raw material for graphene production to be used in sports equipment. However, further progress is required on the quality of graphene produced from waste biomass. This paper, therefore, summarizes the properties, structures, and production processes of graphene and its derivatives, as well as the inherent advantages of biomass waste-derived graphene. Finally, this paper reviews graphene's importance and application prospects in sports since this wonder material has made sports equipment available with high-strength and lightweight quality. Moreover, its outstanding thermal and electrical conductivity is exploited to prepare wearable sensors to collect more accurate sports data, thus helping to improve athletes' training levels and competitive performance. Although the large-scale production of biomass waste-derived graphene has yet to be realized, it is expected that its application will expand to various other fields due to the associated low cost and environmental friendliness of the preparation technique.

Effects of mechanical properties of carbon-based nanocomposites on scaffolds for tissue engineering applications: a comprehensive review

Mechanical properties, such as elasticity modulus, tensile strength, elongation, hardness, density, creep, toughness, brittleness, durability, stiffness, creep rupture, corrosion and wear, a low coefficient of thermal expansion, and fatigue limit, are some of the most important features of a biomaterial in tissue engineering applications. Furthermore, the scaffolds used in tissue engineering must exhibit mechanical and biological behaviour close to the target tissue. Thus, a variety of materials has been studied for enhancing the mechanical performance of composites. Carbon-based nanostructures, such as graphene oxide (GO), reduced graphene oxide (rGO), carbon nanotubes (CNTs), fibrous carbon nanostructures, and nanodiamonds (NDs), have shown great potential for this purpose. This is owing to their biocompatibility, high chemical and physical stability, ease of functionalization, and numerous surface functional groups with the capability to form covalent bonds and electrostatic interactions with other components in the composite, thus significantly enhancing their mechanical properties. Considering the outstanding capabilities of carbon nanostructures in enhancing the mechanical properties of biocomposites and increasing their applicability in tissue engineering and the lack of comprehensive studies on their biosafety and role in increasing the mechanical behaviour of scaffolds, a comprehensive review on carbon nanostructures is provided in this study.

Design and development of biodegradable POSS-PCL-Zeolite (β) nano-scaffold for potential applications in bone regeneration

Side effects caused by bone fractures and restrictions on bone regeneration impose an enormous economic burden on the health system of society. To overcome these limitations, tissue engineering and cell-based therapies have been proposed as alternatives to induce and promote bone healing. Still, bone regeneration disadvantages, such as limited and painful surgery, the risk of infection, nerve injury, bleeding, and function damage, have led investigators to find an alternative therapy. In some studies, bone stimulants have prompted scientists to design scaffolds with appropriate physical structure with the possibility of cell adhesion and proliferation, which plays an influential role in the regeneration and repair of bone tissue. PCL nanofiber is an absorbing candidate for the formulation of biocompatible scaffolds used in tissue engineering. To overcome these negative aspects, improve the properties of PCL nanofibers, and based on the biocompatibility and superior mechanical properties of POSS, Polyhedral Oligomeric Silsesquioxane-Polycaprolactone-Zeolite (POSS-PCL-Zeolite) nanocomposite electrospun nanofiber scaffolds were fabricated in the present study. Nanohybrids and nanofibers structures were characterized by FTIR, HNMR, XRD, SEM, EDX, and DSC techniques. We used cellular and molecular assays, including DCFH ROS detection system, gene expression (RUNX-2, Osteocalcin, Nrf2, BAX, VEGF gens), and apoptotic to demonstrate the biocompatibility and induce bone differentiation of formulated POSS-PCL-Zeolite scaffolds. The results showed the biodegradability of POSS-PCL-Zeolite Nano-scaffold and supported the nesting of mesenchymal stem cells (MSCs) and induced bone differentiation by POSS-PCL-Zeolite Nano-scaffold.

A Novel Zwitterionic Hydrogel Incorporated with Graphene Oxide for Bone Tissue Engineering: Synthesis, Characterization, and Promotion of Osteogenic Differentiation of Bone Mesenchymal Stem Cells

Zwitterionic materials are widely applied in the biomedical field due to their excellent antimicrobial, non-cytotoxicity, and antifouling properties but have never been applied in bone tissue engineering. In this study, we synthesized a novel zwitterionic hydrogel incorporated with graphene oxide (GO) using maleic anhydride (MA) as a cross-linking agent by grafted L-cysteine (L-Cys) as the zwitterionic material on maleilated chitosan via click chemistry. The composition and each reaction procedure of the novel zwitterionic hydrogel were characterized via X-ray diffraction (XRD) and Fourier transformed infrared spectroscopy (FT-IR), while the morphology was imaged by scanning electron microscope (SEM). In vitro cell studies, CCK-8 and live/dead assay, alkaline phosphatase activity, W-B, and qRT-CR tests showed zwitterionic hydrogel incorporated with GO remarkably enhanced the osteogenic differentiation of bone mesenchymal stem cells (BMSCs); it is dose-dependent, and 2 mg/mL GO is the optimum concentration. In vivo tests also indicated the same results. Hence, these results suggested the novel zwitterionic hydrogel exhibited porous characteristics similar to natural bone tissue. In conclusion, the zwitterionic scaffold has highly biocompatible and mechanical properties. When GO was incorporated in this zwitterionic scaffold, the zwitterionic scaffold slows down the release rate and reduces the cytotoxicity of GO. Zwitterions and GO synergistically promote the proliferation and osteogenic differentiation of rBMSCs in vivo and in vitro. The optimal concentration is 2 mg/mL GO.

Protein-inorganic hybrid porous scaffolds for bone tissue engineering

Porous scaffolds hold promise in the treatment of bone defects for bone tissue engineering due to their interconnected porous structure and suitable mechanical properties. Herein, LAPONITE® (LAP), which is able to promote osteogenic differentiation, was introduced into regenerated silk fibroin (RSF) porous scaffolds. Due to hydrogen bonding and electrostatic interactions between RSF and LAP, RSF/LAP 3D porous scaffolds were successfully prepared. The pore size, porosity, and mechanical properties of the RSF/LAP 3D porous scaffolds were modulated during the preparation process. Evaluation of the proliferation of bone marrow mesenchymal stem cells (BMSCs) on the RSF/LAP 3D porous scaffolds in vitro indicated that the addition of LAP improved the adhesion and proliferation of cells. Additionally, alkaline phosphatase activity and osteospecific gene expression analysis showed that the RSF/LAP 3D porous scaffolds enhanced the osteogenic differentiation of BMSCs compared to the pristine RSF porous scaffolds, especially with a higher LAP content. The subcutaneous implantation of the RSF/LAP 3D porous scaffolds in rats demonstrated good histocompatibility in vivo. Therefore, RSF/LAP 3D porous scaffolds with good biocompatibility and biodegradability have good application prospects in the field of bone tissue engineering.

The incorporation of β-tricalcium phosphate nanoparticles within silk fibroin composite scaffolds for enhanced bone regeneration: An in vitro and in vivo study

To investigate the osteogenesis of β-tricalcium phosphate nanoparticles-incorporated silk fibroin (SF/β-TCP) composite scaffolds, SF-based scaffolds with different β-TCP proportion (2/1, 1/1, and 1/2) were fabricated by freeze-drying technology in the present study. Structural and physicochemical properties of SF-based scaffolds were evaluated by using scanning electron microscope, X-ray diffraction, Fourier transformed infrared spectroscopy (ATR-FTIR) and transmission electron microscope. Biocompatibility and osteogenesis of SF/β-TCP scaffolds were investigated by using bone marrow mesenchymal stem cells (BMSCs). Eight New Zealand rabbits were selected, while four 8-mm-diameter calvarial defects were created in each rabbit to place SF/β-TCP scaffolds. The harvested specimens at 4 and 12 weeks were used to evaluate the bone forming ability by micro-CT and histological examination. The results suggested incorporation of β-TCP displayed flake-like pore morphology with proper pore sizes. With the increasing proportion of β-TCP, composite scaffolds exhibited higher compressive strength, lower swelling ratio and degradation rate, as well as enhanced biomineralization capacity. Alkaline phosphatase activity and collagen type I expression levels of BMSCs were significantly increased in the presence of β-TCP nanoparticles. All composite scaffolds with different β-TCP proportion had good bone formation ability at 12 weeks. Among them, SF/β-TCP (1/2) scaffold exhibited the favorable osteogenesis capability which had great potential for applications in bone regeneration.

Impact of Graphene Derivatives as Artificial Extracellular Matrices on Mesenchymal Stem Cells

Thanks to stem cells' capability to differentiate into multiple cell types, damaged human tissues and organs can be rapidly well-repaired. Therefore, their applicability in the emerging field of regenerative medicine can be further expanded, serving as a promising multifunctional tool for tissue engineering, treatments for various diseases, and other biomedical applications as well. However, the differentiation and survival of the stem cells into specific lineages is crucial to be exclusively controlled. In this frame, growth factors and chemical agents are utilized to stimulate and adjust proliferation and differentiation of the stem cells, although challenges related with degradation, side effects, and high cost should be overcome. Owing to their unique physicochemical and biological properties, graphene-based nanomaterials have been widely used as scaffolds to manipulate stem cell growth and differentiation potential. Herein, we provide the most recent research progress in mesenchymal stem cells (MSCs) growth, differentiation and function utilizing graphene derivatives as extracellular scaffolds. The interaction of graphene derivatives in human and rat MSCs has been also evaluated. Graphene-based nanomaterials are biocompatible, exhibiting a great potential applicability in stem-cell-mediated regenerative medicine as they may promote the behaviour control of the stem cells. Finally, the challenges, prospects and future trends in the field are discussed.

Three-Dimensional Printing Strategies for Irregularly Shaped Cartilage Tissue Engineering: Current State and Challenges

Although there have been remarkable advances in cartilage tissue engineering, construction of irregularly shaped cartilage, including auricular, nasal, tracheal, and meniscus cartilages, remains challenging because of the difficulty in reproducing its precise structure and specific function. Among the advanced fabrication methods, three-dimensional (3D) printing technology offers great potential for achieving shape imitation and bionic performance in cartilage tissue engineering. This review discusses requirements for 3D printing of various irregularly shaped cartilage tissues, as well as selection of appropriate printing materials and seed cells. Current advances in 3D printing of irregularly shaped cartilage are also highlighted. Finally, developments in various types of cartilage tissue are described. This review is intended to provide guidance for future research in tissue engineering of irregularly shaped cartilage.

Clinical Efficacy of Polycaprolactone β-Calcium Triphosphate Composite for Osteoconduction in Rabbit Bone Defect Model

The combination of β-tricalcium phosphate (β-TCP) with polycaprolactone (PCL) has been considered a promising strategy for designing scaffolds for bone grafting. This study incorporated PCL with commercially available β-TCP (Osteocera^TM) to fabricate an injectable bone substitute and evaluate the effect of PCL on compressive strength and setting time of the hydraulic cement. The mechanical testing was compliant with the ASTM D695 and ASTM C191-13 standards. Results showed that PCL-TCP composite presented a well-defined architecture with uniform pore distribution and a significant increase in compressive strength compared with β-TCP alone. Eighteen rabbits, each with two surgically created bone defects, were treated using the PCL-TCP composites. The composite materials were resorbed and replaced by newly formed bone tissue. Both PCL-TCP and β-TCP demonstrated equivalent clinical effects on osteoconduction property in terms of the percentage of newly formed bone area measured by histomorphometric analysis. PCL-TCP was proven to be as effective as the commercially available β-TCP scaffold (Osteocera^TM).

Surface Chemistry, Crystal Structure, Size and Topography Role in the Albumin Adsorption Process on TiO2 Anatase Crystallographic Faces and Its 3D-Nanocrystal: A Molecular Dynamics Study

TiO2 is widely used in biomaterial implants. The topography, chemical and structural properties of titania surfaces are an important aspect to study. The size of TiO2 nanoparticles synthetized by sol–gel method can influence the responses in the biological environment, and by using appropriate heat treatments different contents of different polymorphs can be formed. Protein adsorption is a crucial step for the biological responses, involving, in particular, albumin, the most abundant blood protein. In this theoretical work, using molecular mechanics and molecular dynamics methods, the adsorption process of an albumin subdomain is reported both onto specific different crystallographic faces of TiO2 anatase and also on its ideal three-dimensional nanosized crystal, using the simulation protocol proposed in my previous theoretical studies about the adsorption process on hydrophobic ordered graphene-like or hydrophilic amorphous polymeric surfaces. The different surface chemistry of anatase crystalline faces and the nanocrystal topography influence the adsorption process, in particular the interaction strength and protein fragment conformation, then its biological activity. This theoretical study can be a useful tool to better understand how the surface chemistry, crystal structure, size and topography play a key role in protein adsorption process onto anatase surface so widely used as biomaterial.

Silk-Based Materials for Hard Tissue Engineering

Hard tissues, e.g., bone, are mechanically stiff and, most typically, mineralized. To design scaffolds for hard tissue regeneration, mechanical, physico-chemical and biological cues must align with those found in the natural tissue. Combining these aspects poses challenges for material and construct design. Silk-based materials are promising for bone tissue regeneration as they fulfill several of such necessary requirements, and they are non-toxic and biodegradable. They can be processed into a variety of morphologies such as hydrogels, particles and fibers and can be mineralized. Therefore, silk-based materials are versatile candidates for biomedical applications in the field of hard tissue engineering. This review summarizes silk-based approaches for mineralized tissue replacements, and how to find the balance between sufficient material stiffness upon mineralization and cell survival upon attachment as well as nutrient supply.

Spider Silk Fusion Proteins for Controlled Collagen Binding and Biomineralization

The development of biomaterials for the interface between tendon and bone is important for realizing functional tendon replacements. Toward the development of new materials for such applications, engineered recombinant spider silk proteins were modified with peptide tag sequences derived from noncollagenous proteins in bone, so-called SIBLING proteins, such as osteopontin and sialoprotein, which are known to interact with collagen and to initiate mineralization. Materials made of these spider silk-SIBLING hybrids were analyzed concerning mineralization and interaction with cells. They showed enhanced calcium phosphate formation upon incubation in mineralization agents. In gradient films, MC3T3-E1 mouse preosteoblasts adhered preferentially along the gradient toward the variant with a collagen binding motif.

Polymethyl Methacrylate-Based Bone Cements Containing Carbon Nanotubes and Graphene Oxide: An Overview of Physical, Mechanical, and Biological Properties

Every year, millions of people in the world get bone diseases and need orthopedic surgery as one of the most important treatments. Owing to their superior properties, such as acceptable biocompatibility and providing great primary bone fixation with the implant, polymethyl methacrylate (PMMA)-based bone cements (BCs) are among the essential materials as fixation implants in different orthopedic and trauma surgeries. On the other hand, these BCs have some disadvantages, including Lack of bone formation and bioactivity, and low mechanical properties, which can lead to bone cement (BC) failure. Hence, plenty of studies have been concentrating on eliminating BC failures by using different kinds of ceramics and polymers for reinforcement and also by producing composite materials. This review article aims to evaluate mechanical properties, self-setting characteristics, biocompatibility, and bioactivity of the PMMA-based BCs composites containing carbon nanotubes (CNTs), graphene oxide (GO), and carbon-based compounds. In the present study, we compared the effects of CNTs and GO as reinforcement agents in the PMMA-based BCs. Upcoming study on the PMMA-based BCs should concentrate on trialing combinations of these carbon-based reinforcing agents as this might improve beneficial characteristics.