Silk Fibroin as a Green Material

From molecular mechanisms to clinical translation: Silk fibroin-based biomaterials for next-generation wound healing

Silk fibroin (SF) is a natural polymeric material that has attracted intense research attention in the field of wound healing due to its exceptional mechanical properties, tunable biodegradability, and multifunctional bioactivity. This review systematically summarizes the preparation strategies, functional modifications, and multidimensional application mechanisms of SF and its composite materials in wound healing. The innovative applications of SF in intelligent dressing design, immunometabolic regulation, controlled drug release, stem-cell function modulation, and bioelectrical-activity-mediated microenvironment remodeling is further explored, while analyzing the therapeutic efficacy and cost-effectiveness of SF through clinical translation cases. Distinct from previous reviews, this work not only integrates the latest advances in SF molecular mechanisms and material design but also emphasizes its potential in precision medicine, such as the development of genetically engineered SF for customized immunoregulatory networks. Finally, the article highlights the current challenges in the development of SF materials, including mechanical stability, degradation controllability, and standardization of large-scale production, and envisions future research directions driven by 3D bioprinting and synthetic biology technologies. This review provides a theoretical foundation and technical reference information for the development of efficient, multifunctional, and clinically translatable SF-based materials for application in wound healing.

Sustainable and standardized fabrication, recycling, and sterilization of salt-bed casted silk fibroin sponges

Silk fibroin, as a highly versatile biomaterial, is increasingly applied in research, medicine and other sterile applications. The rising usage calls for a robust, standardized and reproducible silk scaffold production and a higher need for silk resources. In this study we standardized the silk fibroin sponges fabrication, set up a quality control protocol, introduced a recycling method to reduce the resources needed and analyzed a sterilization method for translation into preclinical applications. In overall, the development of a fast and efficient quality control protocol led to a reduction in batch-to-batch variabilities. Recycling of silk remnants led to a significant reduction of required silk cocoons of approximately 40 %, with the silk scaffold offering similar product properties as the non-recycled sponges. With the introduction of the recycling trial, we correspond to the requirements for green biomaterials including waste reduction, life cycle introduction and a reduction of environmental impact. Under sterilization conditions, the silk scaffold demonstrated high stability proving that gamma sterilization can be used for bigger batch applications and medical translation. Our establishment of a recycling possibility can pave the way for broader, standardized and "greener" biomedical applications of silk fibroin.

Construction of Cells-Membrane-Cells Living Complexes for Cartilage Repair by Enhancing the Structural Stability of Fibrous Membranes

3D cartilage tissue engineering scaffolds with stable structures are crucial for promoting cartilage tissue growth and repair. However, limited research attention is given to the effects of 3D cells-membrane-cells sandwich-like living complexes with enhanced structural stability for cartilage repair. In this study, silk fibroin/graphene oxide@kartogenin (SF/GO@KGN) fibrous membranes with improved structural stability are developed through the regulation of the crystallinity, and living complexes are constructed for cartilage repair using rat bone marrow stromal cells (rBMSCs) and the SF/GO@KGN fibrous membranes. Results show that the physicochemical properties of the SF/GO@KGN fibrous membranes, including morphology, tensile strength, swelling ratio, degradation, and KGN release rate are greatly influenced by the crystallinity of the fibrous membranes. The enhanced structural stability of the fibrous membranes promotes the adhesion, proliferation, and chondrogenic differentiation of rBMSCs on the surface of the fibrous membranes, as well as the deposition of the cartilage's extracellular matrix (ECM). Animal experiments demonstrate that sandwich-like cells-membrane-cells living complexes with high structural stability significantly promote early cartilage formation and ECM deposition. This study not only provides a facile and effective strategy for cartilage regeneration and repair but also provides new insights for designing and preparing other tissue engineering scaffolds.

Review on application of silk fibroin hydrogels in the management of wound healing

Wounds are regarded as disruptions in the integrity of human skin tissues, and the process of wound healing is often characterized as protracted and complex, primarily due to the potential infection or inflammation caused by microorganisms. The quest for innovative solutions that accelerate wound healing while prioritizing patient safety and comfort has emerged as a focal point. Within this pursuit, silkworm silk fibroin-a natural polymer extracted from silk cocoons-exhibits a distinctive combination of properties including biocompatibility, biodegradability, superior mechanical strength, water absorption, and low immunogenicity, which align closely with the demands of contemporary wound care. Its remarkable biocompatibility facilitates seamless integration with host tissues, thereby minimizing the risk of rejection or adverse reactions. Furthermore, its intrinsic degradability permits controlled release of therapeutic agents, promoting an optimal microenvironment conducive to healing. This review investigates the multifaceted potential of silk fibroin specifically as a wound dressing material and examines the intricate nuances associated with its application in hydrogels for wound healing, aiming to furnish a thorough overview for both researchers and clinicians. By scrutinizing underlying mechanisms, current applications, and prospective directions, we aspire to cultivate new insights and inspire innovative strategies within this rapidly evolving field.

Autonomous Bioelectronic Devices Based on Silk Fibroin

The development of autonomous bioelectronic devices capable of dynamically adapting to changing biological environments represents a significant advancement in healthcare and wearable technologies. Such systems draw inspiration from the precision, adaptability, and self-regulation of biological processes, requiring materials with intrinsic versatility and seamless bio-integration to ensure biocompatibility and functionality over time. Silk fibroin (SF) derived from Bombyx mori cocoons, has emerged as an ideal biomaterial with a unique combination of biocompatibility, mechanical flexibility, and tunable biodegradability. Adding autonomous features into SF, including self-healing, shape-morphing, and controllable degradation, enables dynamic interactions with living tissues while minimizing immune responses and mechanical mismatches. Additionally, structural tunability and environmental sustainability of SF further reinforce its potential as a platform for adaptive implants, epidermal electronics, and intelligent textiles. This review explores recent progress in understanding the structure-property relationships of SF, its modification strategies, and its great potential for integration into advanced autonomous bioelectronic systems while addressing challenges related to scalability, reproducibility, and multifunctionality. Future opportunities, such as AI-assisted material design, scalable fabrication techniques, and the incorporation of wireless and personalized technologies, are also discussed, positioning SF as a key material in bridging the gap between biological systems and artificial technologies.

The effect of silk short fiber biomimetic materials on the recovery of sports function in patients with meniscal injury during sports

BackgroundIn sports, especially high-intensity and high-risk activities, the meniscus is easily damaged. For patients with meniscus injuries, it is necessary to repair or replace the patient's meniscus. However, as age increases, the human meniscus tissue gradually forms and cannot be repaired through its own meniscus. Therefore, it is necessary to maintain the patient's movement function through meniscus support materials.ObjectiveTraditional meniscus support materials have poor mechanical properties and poor biocompatibility. In response to this issue, this study designed a meniscus scaffold made of silk short fibers, silk fibroin, and wool protein.MethodsThrough electrospinning and freeze-drying techniques, the material was processed to obtain a silk short fiber meniscus with a biomimetic structure.ResultsThrough experiments, the surface morphology, hydrophobicity, porosity, secondary structure, thermal stability, water absorption swelling, and MP of MCS made of SSF biomimetic materials were characterized.ConclusionThe experimental results show that the manufactured silk short fiber meniscus has good compressive performance, thermal stability, and water absorption and swelling properties, and it also exhibits good biocompatibility.

Investigation of the Nonlinear Optical Properties of Silk Fibroin (SF) Using the Z-Scan Method

Silk fibroin (SF), the primary protein in silkworm silk, has emerged as a promising organic nonlinear optical material due to its unique combination of optical transparency, biocompatibility, and environmental sustainability. In this study, we investigate the nonlinear optical properties of SF thin films using the z-scan technique with femtosecond laser pulses (35 fs, 800 nm, 1 kHz). Our results reveal a strong self-defocusing effect (negative nonlinear refractive index) and significant multiphoton absorption, demonstrating SF's tunable nonlinear response. Additionally, optical transmittance measurements confirm SF's partial transparency in the deep UV region, enhancing its potential for second-harmonic generation (SHG) and efficient light frequency conversion. These findings address a key knowledge gap in nonlinear optics, positioning SF as a versatile biopolymer for advanced photonic applications.

Defining optimal electrospun membranes to enhance biological activities of human endometrial MSCs

Introduction

Human endometrial mesenchymal stem cells (H-EMSCs) can inhibit endometrial fibrosis and repair damaged endometrium. However, direct cell injection into dam-aged endometrium shows limited cell survival. Cell seeding onto biomaterial-based electrospun membranes could improve H-EMSCs' survival and prolong their stay at the damaged endometrium. Polycaprolactone (PCL), silk fibroin (SF) and hyaluronic acid (HA) are synthetic or natural biomaterials used by the biomedicine field, however, their effects on the biological activities of H-EMSCs remain unclear.

Methods

In this study, CD90+CD73+CD45- H-EMSCs were extracted from human endometrium and H-EMSCs showed enhanced adhesion, proliferation on PCL-HA vs. PCL, PCL-SF, establishing the potential of the composite to address cell survival issues.

Results

H-EMSCs cultured on PCL-HA showed decreased IL-6 gene expression and increased IL-10, VEGFA, TGF-β gene expression vs. PCL-SF, establishing the potential to create a favorable micro-environment for generating vascularized endometrial tissues. PCL, PCL-SF, PCL-HA all supported CD90 and Meflin expression of the seeded H-EMSCs, establishing PCL as a platform to form enhanced biomaterial composites for endometrial repair in the future.

Discussion

This study provided significant evidence sup-porting the potential of appropriately tailored composites of PCL and HA to moder-ate inflammation and wound-healing, which can be applied for endometrial tissue repair and regeneration.

Engineering Injectable and Highly Interconnected Porous Silk Fibroin Microspheres for Tissue Regeneration

Injectable porous microspheres represent a promising therapeutic platform for cell delivery, drug delivery, and tissue regeneration. Yet, the engineering of silk fibroin microspheres with a highly interconnected porous structure remains an unsolved challenge. In this study, a simple and efficient method is developed that does not require the use of organic solvents to prepare silk fibroin microspheres with a predictable structure. Through extensive screening, the addition of glucose is found to direct the formation of a highly interconnected porous structure from the interior to the surface of silk fibroin microspheres. Compared to silk fibroin microspheres (SF microspheres) produced through a combination of electro-spray, cryopreservation, and freeze drying, silk fibroin-glucose microspheres (SF-Glu microspheres) demonstrates enhanced capabilities in promoting cell adhesion and proliferation in vitro. Both SF-Glu and SF microspheres exhibit the capacity to maintain the sustained release kinetics of the loaded model drug. Furthermore, SF-Glu microspheres facilitate the recruitment of endogenous cells, capillary migration, and macrophage phenotype switch following subcutaneous injection in the rats. This study opens a new avenue for the construction of porous silk fibroin microspheres, which could lead to a broader range of applications in regenerative medicine.

Thermoplastic Molding of Silk-Curcumin Sustainable Composite Materials with Antibacterial Properties

Silk fibroin (SF) is a natural protein generated from the Bombyx mori silkworm cocoons. It is useful for many different material applications. Versatile aqueous process engineering options can be used to support the morphological and structural modifications of silk materials related to tailored physical, chemical, and biological properties. Conventional solution-based processing methods, while effective, present process control limitations, thus, thermoplastic molding of regenerated SF-based composites was pursued to fabricate dense, functionalized plastics consisting of silk and curcumin. Curcumin, the active compound in turmeric (Curcuma longa) was incorporated into SF during the high-temperature processing, with the objective to investigate composite thermoplastics with enhanced biological properties from the curcumin due to the protective role of silk during processing. The results showed that a significantly higher amount of curcumin (∼25-fold) could be added into thermoplastic molded silk materials compared with the solution route, attributed to the hydrophobicity and low solubility of curcumin in solution-based routes. The curcumin-incorporated silk thermoplastics provided stability in acidic environments like the human gut, and slow curcumin (∼2% over 8 days) release from the materials. The protective silk-curcumin materials supported improved cytocompatibility with immortalized human colorectal adenocarcinoma (Caco-2) cells at high doses. The intestinal epithelial barrier integrity based on zonula occluden 1 (ZO-1) testing showed that the higher amount of curcumin in the thermoplastic molded silk had no negative effects on the intestinal barrier. The functionalized silk-based plastics also displayed microwave stability and antibacterial efficacy against both Gram-positive S. aureus and Gram-negative E. coli. These silk-based sustainable plastics, functionalized with curcumin, offer potential utility for a range of consumer and medical devices.

Interaction mechanism and compatibility studies of silk protein peptide (SPP) with the common surfactants SDS and DTAB

The molecular interaction of low-molecular-weight SPP with common surfactants (SDS and DTAB) is a more complicated process than has been long believed. In this work, the interaction mechanism between SDS/DTAB and SPP was proposed using multiple methods including conductivity measurements, ST, UV-vis, FT-IR, DLS, fluorescence spectroscopy, and molecular docking simulations. Moreover, the foaming properties of the mixed systems were studied, and they were evaluated as cosmetics preservatives. The effects of various surfactant and protein concentrations and ratios on compatibility and functionality were studied. Based on the results, the mechanism of complex formation was identified as a cooperative van der Waals interaction followed by hydrophobic interaction and hydrogen bonding. A simpler head group leads to easier aggregation and interaction with the SPP, the formation of smaller-sized complexes, and a weaker impact on the fluorescence intensity. Thus, SDS monomers easily aggregate on SPP chains, leading to a stronger influence on the final secondary structure of SPP. This was confirmed by multiple spectroscopy methods. Comparing its single surfactant system, the SDS-SPP solution demonstrates better foaming power and the DTAB-SPP solution shows higher bacteriostatic activity. The good compatibility between SDS/DTAB and SPP can improve the functional properties of SDS or DTAB as well as lower the optimal concentration of each component. These results provide data and theoretical support for the design of cosmetic product formulas.

Engineering collagen-based biomaterials for cardiovascular medicine

Cardiovascular diseases have been the leading cause of global mortality and disability. In addition to traditional drug and surgical treatment, more and more studies investigate tissue engineering therapeutic strategies in cardiovascular medicine. Collagen interweaves in the form of trimeric chains to form the physiological network framework of the extracellular matrix of cardiac and vascular cells, possessing excellent biological properties (such as low immunogenicity and good biocompatibility) and adjustable mechanical properties, which renders it a vital tissue engineering biomaterial for the treatment of cardiovascular diseases. In recent years, promising advances have been made in the application of collagen materials in blood vessel prostheses, injectable cardiac hydrogels, cardiac patches, and hemostatic materials, although their clinical translation still faces some obstacles. Thus, we reviewed these findings and systematically summarizes the application progress as well as problems of clinical translation of collagen biomaterials in the cardiovascular field. The present review contributes to a comprehensive understanding of the application of collagen biomaterials in cardiovascular medicine.

Graphical abstract

Mechanical Properties of Cocoon Silk Derivatives for Biomedical Application: A Systematic Review

BACKGROUND

Despite cocoon silk's well-known strength, biocompatibility, and hypoallergenic properties, its potential medical applications remain largely unexplored. This review, therefore, is of significance as it evaluates the mechanical properties and clinical potential of cocoon silk, a material with promising applications in biomaterials and tissue engineering.

METHODS

We conducted a comprehensive systematic review adhering to PRISMA guidelines. Our focus was on the primary outcomes of tensile strength and elongation at break, and the secondary outcomes included other mechanical properties, applications, and complications.

RESULTS

Out of the 192 silk-related studies, 9 met the criteria. These studies revealed that cocoon silk derivatives exhibit a wide range of tensile strength, from 0.464 to 483.9 MPa (with a median of 4.27 MPa), and elongation at break, from 2.56% to 946.5% (with a median of 60.0%). Biomedical applications of cocoon silk derivatives span from tissue regeneration (n = 6) to energy harvesting (n = 4). Complications often arose from material fragility in non-optimized derivative components.

CONCLUSIONS

While cocoon silk shows expansive promise due to its suitable mechanical properties and low complication risk, plenty remains to be discovered. Future research is crucial to fully realizing its vast surgical and biomedical potential.

Inclusion of Reduced Graphene Oxide to Silk Fibroin Hydrogels Improve the Conductive, Swelling and Wound Healing Capacity

Developing dressing for wound dressings represents a significant challenge for the scientific community. In this study, a conductive hydrogel was synthesized to promote the wound‐healing process. This hydrogel is composed of silk fibroin (SF), reduced graphene oxide (rGO), and glycerol (G). The impact of modifying the SF:rGO ratio, and the G content (%), on the physicochemical and biological properties. The hydrogels were characterized using FT‐IR, SEM, XRD, TGA, swelling, mechanical resistance, and conductivity. The cytotoxicity of the materials and their wound‐healing capacity in human fibroblasts were also determined. Chemical analysis revealed that the gelation of SF occurs due to the formation of β sheet structures, which was confirmed by the shift from amide I to amide II. An Increase in the SF:rGO ratio favored swelling behavior, although increasing G reduced this effect. The swelling of the hydrogel followed a Fick diffusion mechanism. Furthermore, the increase in the SF:rGO ratio and the percentage G improved the conductivity of the materials. The hydrogels were found to be non‐cytotoxic to human fibroblasts, and those containing rGO exhibited superior wound healing capacity compared to the positive control cell culture medium. Therefore, SF:rGO hydrogels could be considered promising candidates for wound dressing.

Efficient Inhibition of Ice Recrystallization During Frozen Storage: Based on the Diffusional Suppression Effect of Silk Fibroin

Effectively controlling ice recrystallization (IR) during the frozen storage of food remains highly challenging. Inspired by the structural characteristics of antifreeze proteins in nature, silk fibroin (SF) derived from silk fibers has been developed. Through dual validation using the "splat" assay and "sucrose sandwich" assay, the IR inhibition activity of SF at various concentrations was confirmed, revealing that its regular alternating hydrophilic/hydrophobic domains endow SF with the potential to inhibit the axial growth of single ice crystal and significantly reduce the average maximum crystal size by approximately 67%. Additionally, the quality stability of frozen muscle foods treated with SF was comprehensively evaluated. In stark contrast to traditional commercial antifreeze agents (4% sucrose and 4% sorbitol), prepared steaks with the addition of 2% SF maintained rich juiciness and excellent color acceptability over a three-month frozen storage period. Thus, SF holds promise as a potential protective agent for frozen muscle foods, enhancing their quality during storage.

3D-Printed Silk Proteins for Bone Tissue Regeneration and Associated Immunomodulation

Current bone repair methods have limitations, prompting the exploration of innovative approaches. Tissue engineering emerges as a promising solution, leveraging biomaterials to craft scaffolds replicating the natural bone environment, facilitating cell growth and differentiation. Among fabrication techniques, three-dimensional (3D) printing stands out for its ability to tailor intricate scaffolds. Silk proteins (SPs), known for their mechanical strength and biocompatibility, are an excellent choice for engineering 3D-printed bone tissue engineering (BTE) scaffolds. This article comprehensively reviews bone biology, 3D printing, and the unique attributes of SPs, specifically detailing criteria for scaffold fabrication such as composition, structure, mechanics, and cellular responses. It examines the structural, mechanical, and biological attributes of SPs, emphasizing their suitability for BTE. Recent studies on diverse 3D printing approaches using SPs-based for BTE are highlighted, alongside advancements in their 3D and four-dimensional (4D) printing and their role in osteo-immunomodulation. Future directions in the use of SPs for 3D printing in BTE are outlined.

Immunomodulatory Antibacterial Hydrogel for Wound Infection Management

Background

Wound healing has always been a focal point in clinical work. Bacterial infections and immune microenvironment disorders can both hinder normal wound healing. Current wound dressings only serve a covering function. Developing wound dressings with antibacterial and immunomodulatory functions is crucial for aiding wound healing. To address this issue, we have developed a hydrogel with antibacterial and immunomodulatory functions for managing infected wounds.

Methods

The present study describes a photo-crosslinked antibacterial hydrogel composed of curcumin, silver nanoparticles-loaded reduced graphene oxide, and silk fibroin methacryloyl for the treatment of infected wounds. The study assessed its antibacterial properties and its capacity to induce macrophage M2 polarization through in vitro and in vivo experiments.

Results

The hydrogel demonstrates robust antibacterial properties and enhances macrophage M2 polarization in both in vitro and in vivo settings. Moreover, it accelerates the healing of infected wounds in vivo by stimulating collagen deposition and angiogenesis.

Conclusion

Overall, this hydrogel shows great potential in managing wound infections.

Silkworm Cocoon: Dual Functions as a Traditional Chinese Medicine and the Raw Material of Promising Biocompatible Carriers

The silkworm cocoon (SC), both as a traditional Chinese medicine and as the raw material for biocompatible carriers, has been extensively used in the medical and biomedical fields. This review elaborates on the multiple functions of SC, with an in-depth analysis of its chemical composition, biological activities, as well as its applications in modern medicine. The primary chemical components of SC include silk fibroin (SF), silk sericin (SS), and other flavonoid-like bioactive compounds demonstrating various biological effects. These include hypoglycemic, cardioprotective, hypolipidemic, anti-inflammatory, antioxidant, and antimicrobial actions, which highlight its potential therapeutic benefits. Furthermore, the review explores the applications of silk-derived materials in drug delivery systems, tissue engineering, regenerative medicine, and in vitro diagnostics. It also highlights the progression of SC from laboratory research to clinical trials, emphasizing the safety and efficacy of SC-based materials across multiple medical domains. Moreover, we discuss the market products developed from silk proteins, illustrating the transition from traditional uses to contemporary medical applications. This review provides support in understanding the current research status of SC and the further development and application of its derived products.

Study on the Structure and Properties of Silk Fibers Obtained from Factory All-Age Artificial Diets

The traditional production mode of the sericulture industry is no longer suitable for the development requirements of modern agriculture; to facilitate the sustainable development of the sericulture industry, factory all-age artificial diet feeding came into being. Understanding the structural characteristics and properties of silk fibers obtained from factory all-age artificial diet feeding is an important prerequisite for application in the fields of textiles, clothing, biomedicine, and others. However, there have been no reports so far. In this paper, by feeding silkworms with factory all-age artificial diets (AD group) and mulberry leaves (ML group), silk fibers were obtained via two different feeding methods. The structure, mechanical properties, hygroscopic properties, and degradation properties were studied by Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and thermogravimetric analysis (TGA). Structurally, no new functional groups appeared in the AD group. Compared with the ML group, the structure of the two groups was similar, and there was no significant difference in mechanical properties and moisture absorption. The structure of degummed silk fibers is dominated by crystalline regions, but α-chymotrypsin hydrolyzes the amorphous regions of silk proteins, so that after 28 d of degradation, the weight loss of both is very small. This provides further justification for the feasibility of factory all-age artificial diets for silkworms.

The Emerging Role of Silk Fibroin for the Development of Novel Drug Delivery Systems

In order to reduce the toxicological impact on healthy cells and to improve the therapeutic response, many drug delivery systems have been fabricated and analysed, involving the use of different natural and synthetic materials at macro-, micro- and nanoscales. Among the natural materials which have demonstrated a huge potential for the development of effective drug delivery systems, silk fibroin has emerged for its excellent biological properties and for the possibility to be processed in a wide range of forms, which can be compliant with multiple active molecules and pharmaceutical ingredients for the treatment of various diseases. This review aims at presenting silk fibroin as an interesting biopolymer for applications in drug delivery systems, exploring the results obtained in recent works in terms of technological progress and effectiveness in vitro and in vivo.

Multifunctional tannic acid-based nanocomposite methacrylated silk fibroin hydrogel with the ability to scavenge reactive oxygen species and reduce inflammation for bone regeneration

The microenvironment of bone defect site is vital for bone regeneration. Severe bone defect is often accompanied with severe inflammation and elevated generation of reactive oxygen species (ROS) during bone repair. In recent years, the unfriendly local microenvironment has been paid more and more attention. Some bioactive materials with the ability to regulate the microenvironment to promote bone regeneration urgently need to be developed. Here, we develop a multifunctional composite hydrogel composed of photo-responsive methacrylate silk fibroin (SFMA), laponite (LAP) nanocomposite and tannic acid (TA), aiming to endow hydrogel with antioxidant, anti-inflammatory and osteogenic induction ability. Characterization results confirmed that the SFMA-LAP@TA hydrogel could significantly improve the mechanical properties of hydrogel. The ROS-Scavenging ability of the hydrogel enabled bone marrow mesenchymal stem cells (BMSCs) to survive against H2O2-induced oxidative stress. In addition, the SFMA-LAP@TA hydrogel effectively decreased the expression of pro-inflammatory factors in RAW264.7. More importantly, the SFMA-LAP@TA hydrogel could enhance the expression of osteogenic markers of BMSCs under inflammatory condition and greatly promote new bone formation in a critical-sized cranial defect model. Above all, the multifunctional hydrogel could effectively promote bone regeneration in vitro and in vivo by scavenging ROS and reducing inflammation, providing a prospective strategy for bone regeneration.

Silk fibroin-based scaffolds for tissue engineering

Silk fibroin is an important natural fibrous protein with excellent prospects for tissue engineering applications. With profound studies in recent years, its potential in tissue repair has been developed. A growing body of literature has investigated various fabricating methods of silk fibroin and their application in tissue repair. The purpose of this paper is to trace the latest developments of SF-based scaffolds for tissue engineering. In this review, we first presented the primary and secondary structures of silk fibroin. The processing methods of SF scaffolds were then summarized. Lastly, we examined the contribution of new studies applying SF as scaffolds in tissue regeneration applications. Overall, this review showed the latest progress in the fabrication and utilization of silk fibroin-based scaffolds.

Fabrication of multifunctional silk nanofibril/hyaluronic acid scaffold for spinal cord repair

Bioactive scaffolds accurately mimicking the structure and composition of the extracellular matrix have garnered significant interest in tissue engineering. In this study, we developed a platform utilizing natural silk nanofibrils, hyaluronic acid, and basic fibroblast growth factor for the purpose of promoting spinal cord regeneration by creating an optimal microenvironment. The bioactive scaffold exhibited notable characteristics such as high porosity and hydrophilicity, attributed to its unique nanostructure, high connectivity, and polysaccharide composition. Furthermore, the pore size of the scaffold can be adjusted within the range of 90 μm to 120 μm by varying the content of hyaluronic acid. In vitro, human umbilical vein endothelial cells were seeded into the scaffold, demonstrating enhanced cell viability. The scaffold facilitated cell proliferation and migration. In vivo experiments on rats indicated that the scaffold had a beneficial impact on spinal cord regeneration, creating a conducive environment for motor function recovery of the rats. This effect may be attributed to the scaffold's ability to stimulate axon growth and neuronal survival, as well as inhibit the formation of glial scars, as evidenced by the decreased expression of growth associated protein-43, microtubule-associated protein 2, and neurofilament-200. This study presents a promising method to develop a feasible bioscaffold for the treatment of spinal cord injury.

Sustainable Bombyx mori's silk fibroin for biomedical applications as a molecular biotechnology challenge: A review

Silk is a natural engineering material with a unique set of properties. The major constituent of silk is fibroin, a protein widely used in the biomedical field because of its mechanical strength, toughness and elasticity, as well as its biocompatibility and biodegradability. The domestication of silkworms allows large amounts of fibroin to be extracted inexpensively from silk cocoons. However, the industrial extraction process has drawbacks in terms of sustainability and the quality of the final medical product. The heterologous production of fibroin using recombinant DNA technology is a promising approach to address these issues, but the production of such recombinant proteins is challenging and further optimization is required due to the large size and repetitive structure of fibroin's DNA and amino acid sequence. In this review, we describe the structure-function relationship of fibroin, the current extraction process, and some insights into the sustainability of silk production for biomedical applications. We focus on recent advances in molecular biotechnology underpinning the production of recombinant fibroin, working toward a standardized, successful and sustainable process.

Thermodynamic Analysis of Silk Fibroin-Graphite Hybrid Materials and Their Morphology

Silk fibroin (SF) is a β-sheet-rich protein that is responsible for the remarkable tensile strength of silk. In addition to its mechanical properties, SF is biocompatible and biodegradable, making it an attractive candidate for use in biotic/abiotic hybrid materials. A pairing of particular interest is the use of SF with graphene-based nanomaterials (GBNs). The properties of this interface drive the formation of well-ordered nanostructures and can improve the electronic properties of the resulting hybrid. It was previously demonstrated that SF can form lamellar nanostructures in the presence of graphite; however, the equilibrium morphology and associated driving interactions are not fully understood. In this study, we characterize these interactions between SF and SF lamellar with graphite using molecular dynamics (MD) simulations and umbrella sampling (US). We find that SF lamellar nanostructures have strong orientational and spatial preferences on graphite that are driven by the hydrophobic effect, destabilizing solvent-protein interactions and stabilizing protein-protein and protein-graphite interactions. Finally, we show how careful consideration of these underlying interactions can be applied to rationally modify the nanostructure morphology.

Next-generation self-adhesive dressings: Highly stretchable, antibacterial, and UV-shielding properties enabled by tannic acid-coated cellulose nanocrystals

Hydrogels with excellent high-water uptake and flexibility have great potential for wound dressing. However, pure hydrogels without fiber skeleton faced poor water retention, weak fatigue resistance, and mechanical strength to hinder the development of the dressing as next-generation functional dressings. We prepared an ultrafast gelation (6 s) Fe3+/TA-CNC hydrogel (CTFG hydrogel) based on a self-catalytic system and bilayer self-assembled composites. The CTFG hydrogel has excellent flexibility (800% of strain), fatigue resistance (support 60% compression cycles), antibacterial, and self-adhesive properties (no residue or allergy after peeling off the skin). CTFG@S bilayer composites were formed after electrospun silk fibroin (SF) membranes were prepared and adhesive with CTFG hydrogels. The CTFG@S bilayer composites had significant UV-shielding (99.95%), tensile strain (210.9 KPa), and sensitive humidity-sensing properties. Moreover, the integrated structure improved the mechanical properties of electrospun SF membranes. This study would provide a promising strategy for rapidly preparing multifunctional hydrogels for wound dressing.

The single-cell modification strategies for probiotics delivery in inflammatory bowel disease: A review

Oral probiotic therapy has become an increasingly attractive method for treating various diseases, including intestinal barrier dysfunction, inflammatory bowel disease (IBD), and colorectal cancer due to its safety and convenience. However, only a few probiotics after oral gavage can survive the acidic and bile salt conditions of the gastrointestinal tract and colonize the colon to have a nutritional effect on the host. To address these challenges, encapsulation technology has been applied to protect probiotics from harsh gastrointestinal conditions, improve gut adhesion, and reduce immunogenicity. In addition, some of the functional polysaccharides are used to endow probiotics with exogenous functions as prebiotics. In this review, we systematically introduced the advancements of emerging single-cell modification strategies for probiotics in IBD applications. Additionally, we discussed the limitations and perspectives of single-cell modification strategies for probiotics. This review contributed to the development of probiotic delivery systems with higher therapeutic efficacy against colitis.

Advances of regenerated and functionalized silk biomaterials and application in skin wound healing

The cocoon silk of silkworms (Bombyx mori) has multiple potential applications in biomedicine due to its good biocompatibility, mechanical properties, degradability, and plasticity. Numerous studies have confirmed that silk material dressings are more effective than traditional ones in the skin wound healing process. Silk material research has recently moved toward functionalized biomaterials and achieved remarkable results. Herein, we summarize the recent advances in functionalized silk materials and their efficacy in skin wound healing. In particular, transgenic technology has realized the specific expression of human growth factors in the silk glands of the silkworms, which lays the foundation for fabricating novel and low-cost functionalized materials. Without a green and safe preparation process, the best raw silk materials cannot be made into medically safe products. Therefore, we provide an overview of green and gentle approaches for silk degumming and silk sericin (SS) extraction. Moreover, we summarize and discuss the processing methods of silk fibroin (SF) and SS materials and their potential applications, such as burns, diabetic wounds, and other wounds. This review aims to enhance our understanding of new advances and directions in silk materials and guide future biomedical research.

Silk fibroin-derived electrospun materials for biomedical applications: A review

Electrospinning is a versatile technique for fabricating polymeric fibers with diameters ranging from micro- to nanoscale, exhibiting multiple morphologies and arrangements. By combining silk fibroin (SF) with synthetic and/or natural polymers, electrospun materials with outstanding biological, chemical, electrical, physical, mechanical, and optical properties can be achieved, fulfilling the evolving biomedical demands. This review highlights the remarkable versatility of SF-derived electrospun materials, specifically focusing on their application in tissue regeneration (including cartilage, cornea, nerves, blood vessels, bones, and skin), disease treatment (such as cancer and diabetes), and the development of controlled drug delivery systems. Additionally, we explore the potential future trends in utilizing these nanofibrous materials for creating intelligent biomaterials, incorporating biosensors and wearable sensors for monitoring human health, and also discuss the bottlenecks for its widespread use. This comprehensive overview illuminates the significant impact and exciting prospects of SF-derived electrospun materials in advancing biomedical research and applications.

Natural polymer-based bioadhesives as hemostatic platforms for wound healing

Medical adhesives are advanced but challenging alternatives to wound closure and repair, especially in mitigating uncontrolled hemorrhage. Ideal hemostatic adhesives need to meet good biocompatibility and biodegradability, adequate mechanical strength, and strong tissue adhesion functionality under wet and dynamic conditions. Considering these requirements, natural polymers such as polysaccharide, protein and DNA, attract great attention as candidates for making bioadhesives because of their distinctive physicochemical performances and biological properties. This review systematically summarizes the advances of bioadhesives based on natural polysaccharide, protein and DNA. Various physical and chemical cross-linking strategies have been introduced for adhesive synthesis and their hemostatic applications are introduced from the aspect of versatility. Furthermore, the possible challenges and future opportunities of bioadhesives are discussed, providing insights into the development of high-performance hemostatic materials.

Advanced Applications of Silk-Based Hydrogels for Tissue Engineering: A Short Review

Silk has been consistently popular throughout human history due to its enigmatic properties. Today, it continues to be widely utilized as a polymer, having first been introduced to the textile industry. Furthermore, the health sector has also integrated silk. The Bombyx mori silk fibroin (SF) holds the record for being the most sustainable, functional, biocompatible, and easily produced type among all available SF sources. SF is a biopolymer approved by the FDA due to its high biocompatibility. It is versatile and can be used in various fields, as it is non-toxic and has no allergenic effects. Additionally, it enhances cell adhesion, adaptation, and proliferation. The use of SF has increased due to the rapid advancement in tissue engineering. This review comprises an introduction to SF and an assessment of the relevant literature using various methods and techniques to enhance the tissue engineering of SF-based hydrogels. Consequently, the function of SF in skin tissue engineering, wound repair, bone tissue engineering, cartilage tissue engineering, and drug delivery systems is therefore analysed. The potential future applications of this functional biopolymer for biomedical engineering are also explored.

Layer-by-Layer Deposition of Regenerated Silk Fibroin─An Approach to the Surface Coating of Biomedical Implant Materials

Biomaterials and coating techniques unlock major benefits for advanced medical therapies. Here, we explored layer-by-layer (LbL) deposition of silk fibroin (SF) by dip coating to deploy homogeneous films on different materials (titanium, magnesium, and polymers) frequently used for orthopedic and other bone-related implants. Titanium and magnesium specimens underwent preceding plasma electrolytic oxidation (PEO) to increase hydrophilicity. This was determined as surface properties were visualized by scanning electron microscopy and contact angle measurements as well as Fourier transform infrared spectroscopy (FTIR) analysis. Finally, biological in vitro evaluations of hemocompatibility, THP-1 cell culture, and TNF-α assays were conducted. A more hydrophilic surface could be achieved using the PEO surface, and the contact angle for magnesium and titanium showed a reduction from 73 to 18° and from 58 to 17°, respectively. Coating with SF proved successful on all three surfaces, and coating thicknesses of up to 5.14 μm (±SD 0.22 μm) were achieved. Using FTIR analysis, it was shown that the insolubility of the material was achieved by post-treatment with water vapor annealing, although the random coil peak (1640-1649 cm-1) and the α-helix peak (at 1650 cm-1) were still evident. SF did not change hemocompatibility, regardless of the substrate, whereas the PEO-coated materials showed improved hemocompatibility. THP-1 cell culture showed that cells adhered excellently to all of the tested material surfaces. Interestingly, SF coatings induced a significantly higher amount of TNF-α for all materials, indicating an inflammatory response, which plays an important role in a variety of physiological processes, including osteogenesis. LbL coatings of SF are shown to be promising candidates to modulate the body's immune response to implants manufactured from titanium, magnesium, and polymers. They may therefore facilitate future applications for bioactive implant coatings. However, further in vivo studies are needed to confirm the proposed effects on osteogenesis in a physiological environment.

Translational Challenges and Prospective Solutions in the Implementation of Biomimetic Delivery Systems

Biomimetic delivery systems (BDSs), inspired by the intricate designs of biological systems, have emerged as a groundbreaking paradigm in nanomedicine, offering unparalleled advantages in therapeutic delivery. These systems, encompassing platforms such as liposomes, protein-based nanoparticles, extracellular vesicles, and polysaccharides, are lauded for their targeted delivery, minimized side effects, and enhanced therapeutic outcomes. However, the translation of BDSs from research settings to clinical applications is fraught with challenges, including reproducibility concerns, physiological stability, and rigorous efficacy and safety evaluations. Furthermore, the innovative nature of BDSs demands the reevaluation and evolution of existing regulatory and ethical frameworks. This review provides an overview of BDSs and delves into the multifaceted translational challenges and present emerging solutions, underscored by real-world case studies. Emphasizing the potential of BDSs to redefine healthcare, we advocate for sustained interdisciplinary collaboration and research. As our understanding of biological systems deepens, the future of BDSs in clinical translation appears promising, with a focus on personalized medicine and refined patient-specific delivery systems.

A novel method for silkworm cocoons self-degumming and its effect on silk fibers

INTRODUCTION

Conventional hot-alkaline cocoon degumming techniques greatly weaken the physicochemical and mechanical properties of silk fibroin fiber, thus affecting the quality of silk fabric. Moreover, it causes massive energy waste and serious environmental pollution.

OBJECTIVE

This study aims to establish a novel cocoon self-degumming method by genetic modification of silkworm varieties and silk fibers.

METHODS

The self-degummed cocoon material was generated by specifically overexpressing trypsinogen protein in the sericin layer of silk thread; the effect of cocoon self-degumming method was evaluated by the degumming rate of sericin protein, the cleanliness and equivalent diameter of silk fibroin fiber; the basic characteristics of silk fibroin fiber degummed by cocoon self-degumming method and conventional hot-alkaline degumming technique were determined by electron microscopy, Fourier infrared spectroscopy, X-ray diffraction and tensile tests; the composition and biological activity of degummed sericin protein was respectively analyzed by liquid chromatograph-mass spectrometry and cytological experiments.

RESULTS

The genetically engineered self-degumming cocoon containing trypsinogen protein was successfully created, and the content of trypsinogen protein in silk was 47.14 ± 0.90 mg/g. The sericin protein in the self-degumming cocoon was removed out in water or 1 mM Tris-HCl buffer (pH = 8.0). Compared to alkaline-degummed silk fibroin, self-degummed silk fibroin had better cleanliness, thicker equivalent diameter, more complete silk structure and better mechanical property. In addition, sericin protein degummed from self-degumming cocoons significantly promoted cell proliferation and caused no obvious cytotoxicity.

CONCLUSION

Compared to conventional hot-alkaline degumming technique, the cocoon self-degumming method by genetically overexpressing trypsinogen protein in sericin layer of silk thread can self-degummed in a mild degumming condition, and gain silk fiber with better quality and more biologically active sericin protein products. This strategy can not only reduce the environmental impact, but also generate greater economic value, which will accelerate its application in the silk and pharmaceutical industries.

The recombinant BMP-2 loaded silk fibroin microspheres improved the bone phenotype of mild osteogenesis imperfecta mice

Osteogenesis imperfecta (OI) is an inherited congenital disorder, characterized primarily by decreased bone mass and increased bone fragility. Bone morphogenetic protein-2 (BMP-2) is a potent cytokine capable of stimulating bone formation, however, its rapid degradation and unanticipated in vivo effects restrict its application. The sustained release characteristic of silk fibroin (SF) microspheres may potentially address the aforementioned challenges, nevertheless they have not previously been tested in OI treatment. In the current investigation, recombinant BMP-2 (rBMP-2) loaded SF (rBMP-2/SF) microspheres-based release carriers were prepared by physical adsorption. The SF microparticles were characterized by scanning electron microscopy (SEM) and were investigated for their cytotoxicity behavior as well as the release profile of rBMP-2. The rBMP-2/SF microspheres were administered via femoral intramedullary injection to two genotypes of OI-modeled mice daily for two weeks. The femoral microstructure and histological performance of OI mice were evaluated 2 weeks later. The findings suggested that rBMP-2/SF spheres with a rough surface and excellent cytocompatibility demonstrated an initial rapid release within the first three days (22.15 ± 2.88% of the loaded factor), followed by a transition to a slower and more consistent release rate, that persisted until the 15th day in an in vitro setting. The factor released from rBMP-2/SF particles exhibited favorable osteoinductive activity. Infusion of rBMP-2/SF microspheres, as opposed to blank SF spheres or rBMP-2 monotherapy, resulted in a noteworthy enhancement of femoral microstructure and promoted bone formation in OI-modeled mice. This research may offer a new therapeutic approach and insight into the management of OI. However, further investigation is required to determine the systematic safety and efficacy of rBMP-2/SF microspheres therapy for OI.

Untapped Potential of Deep Eutectic Solvents for the Synthesis of Bioinspired Inorganic-Organic Materials

Since the discovery of deep eutectic solvents (DESs) in 2003, significant progress has been made in the field, specifically advancing aspects of their preparation and physicochemical characterization. Their low-cost and unique tailored properties are reasons for their growing importance as a sustainable medium for the resource-efficient processing and synthesis of advanced materials. In this paper, the significance of these designer solvents and their beneficial features, in particular with respect to biomimetic materials chemistry, is discussed. Finally, this article explores the unrealized potential and advantageous aspects of DESs, focusing on the development of biomineralization-inspired hybrid materials. It is anticipated that this article can stimulate new concepts and advances providing a reference for breaking down the multidisciplinary borders in the field of bioinspired materials chemistry, especially at the nexus of computation and experiment, and to develop a rigorous materials-by-design paradigm.

A comprehensive review of recent advances in silk sericin: Extraction approaches, structure, biochemical characterization, and biomedical applications

Silks are natural polymers that have been widely used for centuries. Silk consists of a filament core protein, termed fibroin, and a glue-like coating substance formed of sericin (SER) proteins. This protein is extracted from the silkworm cocoons (particularly Bombyx mori) and is mainly composed of amino acids like glycine, serine, aspartic acid, and threonine. Silk SER can be obtained using numerous methods, including enzymatic extraction, high-temperature, autoclaving, ethanol precipitation, cross-linking, and utilizing acidic, alkali, or neutral aqueous solutions. Given the versatility and outstanding properties of SER, it is widely fabricated to produce sponges, films, and hydrogels for further use in diverse biomedical applications. Hence, many authors reported that SER benefits cell proliferation, tissue engineering, and skin tissue restoration thanks to its moisturizing features, antioxidant and anti-inflammatory properties, and mitogenic effect on mammalian cells. Remarkably, SER is used in drug delivery depending on its chemical reactivity and pH-responsiveness. These unique features of SER enhance the bioactivity of drugs, facilitating the fabrication of biomedical materials at nano- and microscales, hydrogels, and conjugated molecules. This review thoroughly outlines the extraction techniques, biological properties, and respective biomedical applications of SER.

Biodegradable Microneedles Array with Dual-Release Behavior and Parameter Optimization by Finite Element Analysis

Microneedles (MNs) are particularly attractive for transdermal administration because of the improved safety, patient compliance and convenience. Dissolving MNs could provide rapid transdermal delivery, but with relatively low mechanical strength and almost no sustainability. On the other hand, hydrogel MNs are complicated to fabricate and have risk concerns. Herein, we developed a biodegradable MNs array composed of biocompatible silk fibroin and poly(vinyl alcohol) to overcome these limitations. Finite element analysis was employed for parameter optimization. The MNs array fabricated by the optimal parameters and material displayed sufficient mechanical strength to disrupt stratum corneum and formed microchannels for transdermal delivery. Dual-release profile was observed in the MNs array, with rapid release in the beginning, and prolonged release afterward. This release behavior fits Weibull release model and is favorable for topical application. The initial immediate release can quickly deliver active compounds to reach the therapeutic effective concentration and facilitate skin penetration, and the sustained release may supply the skin with active compounds over a prolonged period. This biodegradable MNs array is easy to fabricate, mechanically robust, could eliminate safety concerns, and provide the sustainability and advantage for large-scale production.

Stem Cell Scaffolds for the Treatment of Spinal Cord Injury—A Review

Spinal cord injury (SCI) is a profoundly debilitating yet common central nervous system condition resulting in significant morbidity and mortality rates. Major causes of SCI encompass traumatic incidences such as motor vehicle accidents, falls, and sports injuries. Present treatment strategies for SCI aim to improve and enhance neurologic functionality. The ability for neural stem cells (NSCs) to differentiate into diverse neural and glial cell precursors has stimulated the investigation of stem cell scaffolds as potential therapeutics for SCI. Various scaffolding modalities including composite materials, natural polymers, synthetic polymers, and hydrogels have been explored. However, most trials remain largely in the preclinical stage, emphasizing the need to further develop and refine these treatment strategies before clinical implementation. In this review, we delve into the physiological processes that underpin NSC differentiation, including substrates and signaling pathways required for axonal regrowth post-injury, and provide an overview of current and emerging stem cell scaffolding platforms for SCI.

Green Routes for Bio-Fabrication in Biomedical and Pharmaceutical Applications

In the last decade, significant advances in nanotechnologies, rising from increasing knowledge and refining of technical practices in green chemistry and bioengineering, enabled the design of innovative devices suitable for different biomedical applications. In particular, novel bio-sustainable methodologies are developing to fabricate drug delivery systems able to sagely mix properties of materials (i.e., biocompatibility, biodegradability) and bioactive molecules (i.e., bioavailability, selectivity, chemical stability), as a function of the current demands for the health market. The present work aims to provide an overview of recent developments in the bio-fabrication methods for designing innovative green platforms, emphasizing the relevant impact on current and future biomedical and pharmaceutical applications.

Silk chemistry and biomedical material designs

Silk fibroin has applications in different medical fields such as tissue engineering, regenerative medicine, drug delivery and medical devices. Advances in silk chemistry and biomaterial designs have yielded exciting tools for generating new silk-based materials and technologies. Selective chemistries can enhance or tune the features of silk, such as mechanics, biodegradability, processability and biological interactions, to address challenges in medically relevant materials (hydrogels, films, sponges and fibres). This Review details the design and utility of silk biomaterials for different applications, with particular focus on chemistry. This Review consists of three segments: silk protein fundamentals, silk chemistries and functionalization mechanisms. This is followed by a description of different crosslinking chemistries facilitating network formation, including the formation of composite biomaterials. Utility in the fields of tissue engineering, drug delivery, 3D printing, cell coatings, microfluidics and biosensors are highlighted. Looking to the future, we discuss silk biomaterial design strategies to continue to improve medical outcomes.

Biocompatible shape-memory poly(propylene carbonate)/silk fibroin blend with body temperature responsiveness

The high value-added medical applications surely represent the leading edge of the shape-memory materials (SMPs) field. Herein, the biomedical SMPs were easily prepared via incorporating silk fibroin (SF) into poly(propylene carbonate) (PPC) through directly melt blending. Based on the intrinsic glass transition of PPC at ∼37 °C, the blends showed a body temperature responsiveness without a complex procedure for adjusting the switching temperature. By varying the SF content, the blend exhibited tunable shape-memory effects (SME), with a first enhancing but then worsening shape recoverability and a stable and excellent shape fixity. And the blend with 3 wt% SF achieved the best SME, enabling an efficient shape reconfiguration under a 37 °C water bath. It was revealed that SF acted as physical cross-links to connect the PPC chains forming a shape-memory network, thus can well retard irreversible the chain slipping of PPC, leading to the improvement of recoverability. Moreover, the results obtained from cell compatibility testing showed the huge application potential of this material in the biomedical field. This work proposed a facile preparation strategy for developing biocompatible body heat actuated shape-memory materials.

Development of a More Environmentally Friendly Silk Fibroin Scaffold for Soft Tissue Applications

A push for environmentally friendly approaches to biomaterials fabrication has emerged from growing conservational concerns in recent years. Different stages in silk fibroin scaffold production, including sodium carbonate (Na₂CO₃)-based degumming and 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP)-based fabrication, have drawn attention for their associated environmental concerns. Environmentally friendly alternatives have been proposed for each processing stage; however, an integrated green fibroin scaffold approach has not been characterized or used for soft tissue applications. Here, we show that the combination of sodium hydroxide (NaOH) as a substitute degumming agent with the popular "aqueous-based" alternative silk fibroin gelation method yields fibroin scaffolds with comparable properties to traditional Na₂CO₃-degummed aqueous-based scaffolds. The more environmentally friendly scaffolds were found to have comparable protein structure, morphology, compressive modulus, and degradation kinetics, with increased porosity and cell seeding density relative to traditional scaffolds. Human adipose-derived stem cells showed high viability after three days of culture while seeded in each scaffold type, with uniform cell attachment to pore walls. Adipocytes from human whole adipose tissue seeded into scaffolds were found to have similar levels of lipolytic and metabolic function between conditions, in addition to a healthy unilocular morphology. Results indicate that our more environmentally friendly methodology for silk scaffold production is a viable alternative and well suited to soft tissue applications.

From crosslinking strategies to biomedical applications of hyaluronic acid-based hydrogels: A review

Hyaluronic acid (HA) is not only a natural anionic polysaccharide with excellent biocompatibility, biodegradability, and moisturizing effect, but also an essential factor that can affect angiogenesis, inflammation, cell behavior, which has a wide range of applications in the biomedical field. Among them, HA-based hydrogels formed by various physical or chemical crosslinking strategies are particularly striking. They not only retain the physiological function of HA, but also have the skeleton function of hydrogel, which further expands the application of HA. However, HA-based natural hydrogels generally have problems such as insufficient mechanical strength and susceptibility to degradation by hyaluronidase, which limits their application to a certain extent. To solve such problems, researchers have prepared a variety of HA-based multifunctional hydrogels with remarkable properties in recent years by adopting various structural modification methods or novel crosslinking strategies, as well as introducing functionally reactive molecules or moieties, which have extended the application scope. This manuscript systematically introduced common crosslinking strategies of HA-based hydrogels and highlighted the development of novel HA-based hydrogels in anticancer drug delivery, cartilage repair, three-dimensional cell culture, skin dressing and other fields. We hope to provide some references for the subsequent development of HA-based hydrogels in the biomedical field.

Progress in self-healing hydrogels and their applications in bone tissue engineering

Bone tissue engineering (BTE) is constantly seeking novel treatments to address bone injuries in all their varieties. It is necessary to find new ways to create structures that perfectly emulate the native tissue. Self-healing hydrogels have been a breakthrough in this regard, as they are able to reconstitute their links after they have been partially broken. Among the most outstanding biomaterials when it comes to developing these hydrogels for BTE, those polymers of natural origin (e.g., gelatin, alginate) stand out, although synthetics such as PEG or nanomaterials like laponite are also key for this purpose. Self-healing hydrogels have proven to be efficient in healing bone, but have also played a key role as delivery-platforms for drugs or other biological agents. Moreover, some researchers have identified novel uses for these gels as bone fixators or implant coatings. Here, we review the progress of self-healing hydrogels, which hold great promise in the field of tissue engineering.

A Comprehensive Review on Silk Fibroin as a Persuasive Biomaterial for Bone Tissue Engineering

Bone tissue engineering (BTE) utilizes a special mix of scaffolds, cells, and bioactive factors to regulate the microenvironment of bone regeneration and form a three-dimensional bone simulation structure to regenerate bone tissue. Silk fibroin (SF) is perhaps the most encouraging material for BTE given its tunable mechanical properties, controllable biodegradability, and excellent biocompatibility. Numerous studies have confirmed the significance of SF for stimulating bone formation. In this review, we start by introducing the structure and characteristics of SF. After that, the immunological mechanism of SF for osteogenesis is summarized, and various forms of SF biomaterials and the latest development prospects of SF in BTE are emphatically introduced. Biomaterials based on SF have great potential in bone tissue engineering, and this review will serve as a resource for future design and research.

Biomedical applications of silk and its role for intervertebral disc repair

Intervertebral disc (IVD) degeneration (IDD) is the main contributor to chronic low back pain. To date, the present therapies mainly focus on treating the symptoms caused by IDD rather than addressing the problem itself. For this reason, researchers have searched for a suitable biomaterial to repair and/or regenerate the IVD. A promising candidate to fill this gap is silk, which has already been used as a biomaterial for many years. Therefore, this review aims first to elaborate on the different origins from which silk is harvested, the individual composition, and the characteristics of each silk type. Another goal is to enlighten why silk is so suitable as a biomaterial, discuss its functionalization, and how it could be used for tissue engineering purposes. The second part of this review aims to provide an overview of preclinical studies using silk-based biomaterials to repair the inner region of the IVD, the nucleus pulposus (NP), and the IVD's outer area, the annulus fibrosus (AF). Since the NP and the AF differ fundamentally in their structure, different therapeutic approaches are required. Consequently, silk-containing hydrogels have been used mainly to repair the NP, and silk-based scaffolds have been used for the AF. Although most preclinical studies have shown promising results in IVD-related repair and regeneration, their clinical transition is yet to come.

Comparative transcriptome and proteome reveal synergistic functions of differentially expressed genes and proteins implicated in an over-dominant silkworm heterosis of increased silk yield

We previously observed an over-dominant silkworm heterosis of increased yield in a cross of Bombyx mori nuclear polyhydrosis virus-resistant strain NB with a susceptible strain 306. In the present study, we found that heterosis also exists in crosses of NB with other susceptible strains, indicating it is a more general phenomenon. We performed comparative transcriptome and proteome and identified 1624 differentially expressed genes (DEGs) and 298 differentially expressed proteins (DEPs) in silk glands between parents and F1 hybrids, of which 24 DEGs/DEPs showed consistent expression at mRNA and protein levels revealed by Venn joint analysis. Their expressions are completely non-additive, mainly transgressive and under low-parent, suggesting recombination of parental genomes may be the major genetic mechanism for the heterosis. GO and KEGG analyses revealed that they may function in generally similar but distinctive aspects of metabolisms and processes with signal transduction and translation being most affected. Notably, they may not only up-regulate biosynthesis and transport of silk proteins but also down-regulate other unrelated processes, synergistically and globally remodelling the silk gland to increase yield and cause the heterosis. Our findings contribute insights into the understanding of silkworm heterosis and silk gland development and provide targets for transgenic manipulation to further increase the silk yield.