Strong and biocompatible three-dimensional porous silk fibroin/graphene oxide scaffold prepared by phase separation

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.

A Short Review on Nanostructured Carbon Containing Biopolymer Derived Composites for Tissue Engineering Applications

The development of new scaffolds and materials for tissue engineering is a wide and open realm of material science. Among solutions, the use of biopolymers represents a particularly interesting area of study due to their great chemical complexity that enables creation of specific molecular architectures. However, biopolymers do not exhibit the properties required for direct application in tissue repair-such as mechanical and electrical properties-but they do show very attractive chemical functionalities which are difficult to produce through in vitro synthesis. The combination of biopolymers with nanostructured carbon fillers could represent a robust solution to enhance composite properties, producing composites with new and unique features, particularly relating to electronic conduction. In this paper, we provide a review of the field of carbonaceous nanostructure-containing biopolymer composites, limiting our investigation to tissue-engineering applications, and providing a complete overview of the recent and most outstanding achievements.

Advancements and Applications in the Composites of Silk Fibroin and Graphene-Based Materials

Silk fibroin and three kinds of graphene-based materials (graphene, graphene oxide, and reduced graphene oxide) have been widely investigated in biomedical fields. Recently, the hybrid composites of silk fibroin and graphene-based materials have attracted much attention owing to their combined advantages, i.e., presenting outstanding biocompatibility, mechanical properties, and excellent electrical conductivity. However, maintaining bio-toxicity and biodegradability at a proper level remains a challenge for other applications. This report describes the first attempt to summarize the hybrid composites’ preparation methods, properties, and applications to the best of our knowledge. We strongly believe that this review will open new doors for coming researchers.

Bioactive Silk Fibroin-Based Hybrid Biomaterials for Musculoskeletal Engineering: Recent Progress and Perspectives

Musculoskeletal engineering has been considered as a promising approach to customize regenerated tissue (such as bone, cartilage, tendon, and ligament) via a self-healing performance. Recent advances have demonstrated the great potential of bioactive materials for regenerative medicine. Silk fibroin (SF), a natural polymer, is regarded as a remarkable bioactive material for musculoskeletal engineering thanks to its biocompatibility, biodegradability, and tunability. To improve tissue-engineering performance, silk fibroin is hybridized with other biomaterials to form silk-fibroin-based hybrid biomaterials, which achieve superior mechanical and biological performance. Herein, we summarize the recent development of silk-based hybrid biomaterials in musculoskeletal tissue with reasonable generalization and classification, mainly including silk fibroin-based inorganic and organic hybrid biomaterials. The applied inorganics are composed of calcium phosphate, graphene oxide, titanium dioxide, silica, and bioactive glass, while the polymers include polycaprolactone, collagen (or gelatin), chitosan, cellulose, and alginate. This article mainly focuses on the physical and biological performances both in vitro and in vivo study of several common silk-based hybrid biomaterials in musculoskeletal engineering. The timely summary and highlight of silk-fibroin-based hybrid biomaterials will provide a research perspective to promote the further improvement and development of silk fibroin hybrid biomaterials for improved musculoskeletal engineering.

Novel fabrication of antibiotic containing multifunctional silk fibroin injectable hydrogel dressing to enhance bactericidal action and wound healing efficiency on burn wound: In vitro and in vivo evaluations

The development of biologically active multifunctional hydrogel wound dressings can assist effectively to wound regeneration and also has influenced multiple functions on wound injury. Herein, we designed a carbon-based composited injectable silk fibroin hydrogel as multifunctional wound dressing to provide effective anti-bacterial, cell compatibility and in vivo wound closure actions. Importantly, the fabricated injectable hydrogel exhibit sustained drug delivery properties, anti-oxidant and self-healing abilities, which confirm that composition of hydrogel is highly beneficial to tissue adhesions and burn wound regeneration ability. Frequently, designed injectable hydrogel can be injected into deep and irregular burn wound sites and would provide rapid self-healing and protection from infection environment with thoroughly filled wound area. Meanwhile, incorporated carbon nanofillers improve injectable hydrogel strength and also offer high fluid uptake to hydrogel when applied on the wound sites. In vitro MTT cytotoxicity assay on human fibroblast cell lines establish outstanding cytocompatibility of the injectable hydrogel and also have capability to support cell growth and proliferations. In vivo burn wound animal model results demonstrate that the hydrogel dressings predominantly influenced enhanced wound contraction and also promoted greater collagen deposition, granulation tissue thickness and vascularization. This investigation's outcome could open a new pathway to fabricate multifunctional biopolymeric hydrogel for quicker burn wound therapy and effectively prevents microenvironment bacterial infections.

Bionic Silk Fibroin Film Induces Morphological Changes and Differentiation of Tendon Stem/Progenitor Cells

Purpose

Tendon injuries are common musculoskeletal system disorders, but the ability for tendon regeneration is limited. Silk fibroin (SF) film may be suitable for tendon regeneration due to its excellent biocompatibility and physical properties. This study is aimed at evaluating the application value of bionic SF film in tendon regeneration.

Methods

Tendon stem/progenitor cells (TSPCs) were isolated from rat Achilles tendon and characterized based on their surface marker expression and multilineage differentiation potential. SF films with smooth or bionic microstructure surfaces (5, 10, 15, 20 μm) were prepared. The morphology and mechanical properties of natural tendons and SF films were characterized. TSPCs were used as the seed cells, and the cell viability and cell adhesion morphology were analyzed. The tendongenesis-related gene expression of TSPCs was also evaluated using quantitative polymerase chain reaction.

Results

Compared to the native tendon, only the 10, 15, and 20 μm SF film groups had comparable maximum loading and ultimate stress, with the exception of the breaking elongation rate. The 10 μm SF film group had the highest percentage of oriented cells and the most significant changes in cell morphology. The most significant upregulations in the expression of COL1A1, TNC, TNMD, and SCX were also observed in the 10 μm SF film group.

Conclusion

SF film with a bionic microstructure can serve as a tissue engineering scaffold and provide biophysical cues for the use of TSPCs to achieve proper cellular adherence arrangement and morphology as well as promote the tenogenic differentiation of TSPCs, making it a valuable customizable biomaterial for future applications in tendon repair.

Biofabricating a Silk Scaffold as a Functional Microbial Trap

Silk fibroin produced from silkworms has been intensively utilized as a scaffold material for a variety of biotechnological applications owing to its remarkable mechanical strength, extensibility, biocompatibility, and ease of biofunctionalization. In this research, we engineered silk as a novel trap platform capable of capturing microorganisms. Specifically, we first fabricated the silk material into a silk sponge by lyophilization, yielding a 3D scaffold with porous microstructures. The sponge stability in water was significantly improved by ethanol treatment with elevated β-sheet content and crystallinity of silk. Next, we biofunctionalized the silk sponge with a poly-specific microbial targeting molecule, ApoH (apolipoprotein H), to enable a novel silk-based microbial trap. The recombinant ApoH engineered with an additional penta-tyrosine was assembled onto the silk sponge through the horseradish peroxidase (HRP) mediated dityrosine cross-linking. Last, the ApoH-decorated silk sponge was demonstrated to be functional in capturing our model microorganism targets, E. coli and norovirus-like particles. We envision that this biofabricated silk platform, capable of trapping a variety of microbial entities, could serve as a versatile scaffold for rapid isolation and enrichment of microbial samples toward future diagnostics and therapeutics. This strategy, in turn, can expedite advancing future biodevices with functionality and sustainability.

The State of the Art of Energy Harvesting and Storage in Silk Fibroin-Based Wearable and Implantable Devices

The energy autonomy of self-powered wearable electronics depends on the adequate development of new technologies for energy harvesting and energy storage devices based on textile fibers to facilitate the integration with truly flexible and wearable devices. Silk fiber-based systems are attractive for the design of biomedical devices, lithium-ion batteries and flexible supercapacitors, due to their nitrogen-rich structure (for preparation of hierarchical carbon-based structures), and available surface for chemical modification reinforcing electroactive properties for use in batteries and supercapacitors. Herein, this paper reviews recent advances on silk fiber-based systems for harvesting and the storage of energy and the corresponding strategies to reinforce the physical and chemical properties of the resulting composites applied as electrodes and battery separators.

Delivery of Salvianolic Acid B for Efficient Osteogenesis and Angiogenesis from Silk Fibroin Combined with Graphene Oxide

The efficiency of drugs often hinges on drug carriers. To effectively transport therapeutic plant molecules, drug delivery carriers should be able to carry large doses of therapeutic drugs, enable their sustained release, and maintain their biological activity. Here, graphene oxide (GO) is demonstrated to be a valid carrier for delivering therapeutic plant molecules. Salvianolic acid B (SB), which contains a large number of hydroxyl groups, bound to the carboxyl groups of GO by self-assembly. Silk fibroin (SF) substrates were combined with functionalized GO through the freeze-drying method. SF/GO scaffolds could be loaded with large doses of SB, maintain the biological activity of SB while continuously releasing SB, and significantly promote the osteogenic differentiation of rat bone marrow mesenchymal stem cells (rBMSCs). SF/GO/SB also dramatically enhanced endothelial cell (EA-hy9.26) migration and tubulogenesis in vitro. Eight weeks after implantation of SF/GO/SB scaffolds in a rat cranial defect model, the defect area showed more new bone and angiogenesis than that following SF and SF/GO scaffold implantation. Therefore, GO is an effective sustained-release carrier for therapeutic plant molecules, such as SB, which can repair bone defects by promoting osteogenic differentiation and angiogenesis.

Robust Silk Fibroin/Graphene Oxide Aerogel Fiber for Radiative Heating Textiles

Aerogel fibers with ultrahigh porosity and ultralow density are promising candidates for personal thermal management to reduce the energy waste of heating an entire room, and play important roles in reducing energy waste in general. However, aerogel fibers generally suffer from poor mechanical properties and complicated preparation processes. Herein, we demonstrate hierarchically porous and continuous silk fibroin/graphene oxide aerogel fibers (SF/GO) with high strength, excellent radiative heating performance, and thermal insulation performance through coaxial wet spinning and freeze-drying. The hollow CA/PAA fibers prepared via a coaxial wet spinning process have multiscale porous structures, which are not only beneficial for the formation of an SF/GO aerogel core, but also help to improve the mechanical strength of the aerogel fibers. Moreover, the prepared aerogel fibers show comparable porosity and mechanical properties with those of hollow CA/PAA fibers. More importantly, GO can dramatically improve the infrared radiative heating properties, and the surface temperature is increased by 2.6 °C after exposure to infrared radiation for 30 s, greatly higher than that of hollow fiber and SF aerogel fibers. Furthermore, the integration of hierarchically porous hollow fibers and SF/GO aerogels prevents thermal convection, decreases thermal conduction, and suppresses thermal radiation, rendering the SF/GO aerogel fiber with excellent thermal insulation performance. This work may shed light on the heat transfer mechanism of the microenvironment between the human body and textiles and pave the way for the fabrication of high-performance aerogel fibers used for personal thermal management.

Reynoutria Japonica from Traditional Chinese Medicine: A Source of Competitive Adenosine Deaminase Inhibitors for Anticancer

BACKGROUND

Adenosine deaminase (ADA) is an important enzyme in purine metabolism and is known as a potential therapeutic target for the treatment of lymphoproliferative disorders and cancer. Traditional Chinese Herbal Medicine (TCHM) is widely used alone or in combination with chemotherapy to treat cancer, due to its ability to deliver a broad variety of bioactive secondary metabolites as promising sources of novel organic natural agents.

OBJECTIVE

In the present study, 29 varieties of medicinal plants were screened for the presence of ADA inhibitors.

RESULTS

Extracts from Reynoutria japonica, Glycyrrhiza uralensis, Lithospermum erythrorhizon, Magnolia officinalis, Gardenia jasminoides, Stephania tetrandra, Commiphora myrrha, Raphanus sativus and Corydalis yanhusuo demonstrated strong ADA inhibition with rates greater than 50%. However, Reynoutria japonica possessed the highest ADA inhibitory activity at 95.26% and so was used in our study for isolating the ADA inhibitor to be further studied. Eight compounds were obtained and their structures were identified. The compound H1 had strong ADA inhibitory activity and was deduced to be emodin by 1H and 13C-NMR spectroscopic analysis with an IC50 of 0.629 mM. The molecular docking data showed that emodin could bind tightly to the active site of ADA. Our results demonstrated that emodin displayed a new biological activity which is ADA inhibitory activity with high cytotoxic activity against K562 leukemia cells. The bioactivity of cordycepin was significantly increased when used in combination with emodin.

CONCLUSION

Emodin may represent a good candidate anti-cancer therapy and adenosine protective agent.

A new mixed inhibitor of adenosine deaminase produced by endophytic Cochliobolus sp. from medicinal plant seeds

Medicinal plants have been studied for potential endophytic interactions and numerous studies have provided evidence that seeds harbor diverse microbial communities, not only on their surfaces but also within the embryo. Adenosine deaminase (ADA) is known as a potential therapeutic target for the treatment of lymphoproliferative disorders and cancer. Therefore, in this study, 20 types of medicinal plant seeds were used to screen endophytic fungi with tissue homogenate and streak. In addition, 128 morphologically distinct endophyte strains were isolated and their ADA inhibitory activity determined by a spectrophotometric assay. The strain with the highest inhibitory activity was identified as Cochliobolus sp. Seven compounds were isolated from the strain using a chromatography method. Compound 3 showed the highest ADA inhibitory activity and was identified as 5-hydroxy-2-hydroxymethyl-4H-pyran-4-one, based on the results of 1H and 13C NMR spectroscopy. The results of molecular docking suggested that compound 3 binds to the active site and the nonspecific binding site of the ADA. Furthermore, we found that compound 3 is a mixed ADA inhibitor. These results indicate that endophytic strains are a promising source of ADA inhibitors and that compound 3 may be a superior source for use in the preparation of biologically active ADA inhibitor compounds used to treat cancer.

The assembly of silk fibroin and graphene-based nanomaterials with enhanced mechanical/conductive properties and their biomedical applications

The assembly of silk fibroin and graphene-based nanomaterials would present fantastic properties and functions via optimizing the interaction between each other, and can be processed into various formats to tailor specific biomedical applications.

Design, Fabrication, and Function of Silk-Based Nanomaterials

Animal silks are built from pure protein components and their mechanical performance, such as strength and toughness, often exceed most engineered materials. The secret to this success is their unique nanoarchitectures that are formed through the hierarchical self-assembly of silk proteins. This natural material fabrication process in sharp contrast to the production of artificial silk materials, which usually are directly constructed as bulk structures from silk fibroin (SF) molecular. In recent years, with the aim of understanding and building better silk materials, a variety of fabrication strategies have been designed to control nanostructures of silks or to create functional materials from silk nanoscale building blocks. These emerging fabrication strategies offer an opportunity to tailor the structure of SF at the nanoscale and provide a promising route to produce structurally and functionally optimized silk nanomaterials. Here, we review the critical roles of silk nanoarchitectures on property and function of natural silk fibers, outline the strategies of utilization of these silk nanobuilding blocks, and we provide a critical summary of state of the art in the field to create silk nanoarchitectures and to generate silk-based nanocomponents. Further, such insights suggest templates to consider for other materials systems.

[Recent advances in application of graphene oxide for bone tissue engineering]

Objective

To review the recent advances in the application of graphene oxide (GO) for bone tissue engineering.

Methods

The latest literature at home and abroad on the GO used in the bone regeneration and repair was reviewed, including general properties of GO, degradation performance, biocompatibility, and application in bone tissue engineering.

Results

GO has an abundance of oxygen-containing functionalities, high surface area, and good biocompatibility. In addition, it can promote stem cell adhesion, proliferation, and differentiation. Moreover, GO has many advantages in the construction of new composite scaffolds and improvement of the performance of traditional scaffolds.

Conclusion

GO has been a hot topic in the field of bone tissue engineering due to its excellent physical and chemical properties. And many problems still need to be solved.