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Background: Autologous tissues such as buccal mucosa (BM) are widely used for reconstruction of urethral strictures; however, limitations such as donor site morbidity and scarce tissue supply require the development of alternative biomaterials for urethral repair. The goals of this study were to determine the safety and efficacy of bi-layer silk fibroin (BLSF) matrices for urethral stricture repair and compare histological and functional outcomes to the standard approach, BM urethroplasty under good laboratory practices.Material and methods: A total of 13 rabbits exhibiting urethral stricture formation following electrocoagulation injury were treated with onlay urethroplasty with either acellular BLSF (N = 7) or autologous BM (N = 6) grafts for 3 months. Uninjured control rabbits were maintained in parallel (N = 4).Results and conclusion: Animals receiving BLSF implants were demonstrated to be functionally equivalent to BM grafts in their ability to restored strictured calibers, support micturition and promote tissue regeneration with minimal inflammation.

BackgroundAutologous tissues derived from bowel, buccal mucosa and skin are primarily used to repair or replace diseased vaginal segments as well as create neovaginas for male-to-female transgenders. These grafts are often limited by scarce tissue supply, donor site morbidity and post-operative complications. Bi-layer silk fibroin (BLSF) biomaterials represent potential alternatives for vaginoplasty given their structural strength and elasticity, low immunogenicity, and processing flexibility. The goals of the current study were to assess the potential of acellular BLSF scaffolds for vaginal tissue regeneration in respect to conventional small intestinal submucosal (SIS) matrices in a rat model of vaginoplasty.MethodsInlay vaginoplasty was performed with BLSF and SIS scaffolds (N = 21 per graft) in adult female rats for up to 2 months of implantation. Nonsurgical controls (N = 4) were investigated in parallel. Outcome analyses included histologic, immunohistochemical and histomorphometric evaluations of wound healing patterns; µ-computed tomography (CT) of vaginal continuity; and breeding assessments.ResultsAnimals in both scaffold cohorts exhibited 100% survival rates with no severe post-operative complications. At 2 months post-op, µ-CT analysis revealed normal vaginal anatomy and continuity in both graft groups similar to controls. In parallel, BLSF and SIS grafts also induced comparable constructive remodeling patterns and were histologically equivalent in their ability to support formation of vascularized vaginal neotissues with native tissue architecture, however with significantly less smooth muscle content. Vaginal tissues reconstructed with both implants were capable of supporting copulation, pregnancy and similar amounts of live births.ConclusionsBLSF biomaterials represent potential "off-the-shelf" candidates for vaginoplasty.

On‐skin electronics rely on flexible power sources for stable operation and comfortable wearing. However, the current materials and device designs of on‐skin batteries for human‐interface electronic systems suffer from inadequate adhesion and impermeability. In this work, a general design of a bioadhesive and breathable on‐skin flexible metal‐air battery is presented. By laterally loading a conducting polymer‐based cathode and a zinc anode onto a biocompatible silk fibroin ionic hydrogel electrolyte film, the battery exhibits good epidermal adhesions (shear strength exceeds 20 kPa and interface toughness exceeds 150 J m−2) and excellent sweat breathability (3 times greater than commercial 3 M breathable dressing). A singular battery can generate an open circuit voltage of up to 1.4 V and a power density of 72 µW cm−2. It shows stable adhesion to the skin for five days, while simultaneously preserving epidermal respiratory function and facilitating natural skin movement. On‐skin integration of the battery array can be easily conducted to increase the electrical output. This battery design enhances the usability, comfort, and safety of wearable electronics, enabling new applications in healthcare, fitness tracking, and beyond. [ABSTRACT FROM AUTHOR]

Composite electrospun nanofibers based on silk fibroin (SF), aminated reduced graphene oxide (NH2rGO), and oxidized-cellulose nanocrystals (AD-CNCs) were designed to promote the healing process by electrical conductivity. In this respect, CNCs were produced from cotton cellulose and oxidized in the presence of sodium periodate, and reduced GO was synthesized and functionalized with amine with p-anthranilic acid via an esterification reaction. Then the crosslink was prepared by the Schiff-base reaction between oxidized CNCs and NH2rGO. Electrospun nanofibers were prepared from silk fibroin, previously prepared from Bombyx Mori cocoons, AD-CNCs, and different ratios of NH2rGO. The SF/AD-CNCs/NH2rGO nanofibrous scaffold presented multiple propitious characteristics for cell proliferation and wound dressing including low cytotoxicity, a hydrophilic surface, thermal stability, and degradability. The physicochemical evaluations showed that with increasing the NH2rGO content, hydrophilicity and electroconductivity of nanofibers increased. The SF/AD-CNCs/NH2rGO biodegradable conductive scaffold with 2.5% NH2rGO content showed favorable nanofibrous structure, supporting and stimulating fibroblast cell proliferation and attachment. The SF/AD-CNCs/NH2rGO nanofibrous scaffold demonstrates the application potential in wound healing management. [ABSTRACT FROM AUTHOR]

The use of biodegradable materials combined with natural metabolites in wound dressings has received much attention. Flavonoids (FLs) from green cocoons, as metabolites, have antibacterial, antioxidant, anti-inflammatory, and other pharmacological effects. In this study, composite membranes of FL-loaded polylactic glycolic acid (PLGA)/silk fibroin (SF) were prepared by an electrospinning method. The prepared membranes, including SF, exhibited a good slow-release effect and cytocompatibility. An in vitro evaluation of the FL-loaded PLGA/SF membranes demonstrated good antioxidant, antibacterial, and anti-inflammatory properties. Animal experiments showed that the wound healing rate of PLGA/SF-2.5FL membranes within 15 days was 97.3%, and that of the control group was 72.5%. The PLGA/SF-2.5FL membranes shortened the inflammatory period of a full-layer wound model and promoted skin regeneration and wound healing by downregulating expression of the pro-inflammatory cytokines IL-1β and TNF-α and promoting expression of the growth factors VEGF, TGF-β, and EGF. In summary, the PLGA/SF-2.5FL composite nanofibre membrane with anti-inflammatory properties is an ideal wound dressing to promote acute wound healing. [ABSTRACT FROM AUTHOR]

Silk fibroin (SF)–chondroitin sulfate (CS)-hybrid hydrogels (HHGs) containing kartogenin (KGN) were synthesized by the induction of di-tyrosine bonds, using enzymatic crosslinking in SF/CS blend solution. Then, physical crosslinking was performed to optimize the HHG properties. The results showed that the increasing of the β-sheet content as side effect of physical crosslinking from 10% to 40% affects KGN accumulative release percentage almost three times. Biological investigations using C28/I2 human chondrocyte cell line showed that the presence of KGN, CS, and optimized β-sheets content improved cell supporting behavior of HHG. Finally, KGN loaded HHG might be a promising candidate for cartilage repair. Schematic representation of fabrication of the dual crosslinked hybrid hydrogel containing silk fibroin and chondroitin sulfate by enzymatic crosslinking and physical crosslinking method for kartogenin release. Enzymatic crosslinking: shaping di-tyrosine formation bond between silk fibroin phenol groups and locking physically chondroitin sulfate between silk fibroin β-sheets. Physical crosslinking with water and/or ethanol treatments end up in increased β-sheets content. [ABSTRACT FROM AUTHOR]

Here, a novel kind of composite scaffold was fabricated by loading vascular endothelial growth factor (VEGF) and gastrodin liposome (GAS-LP) into electrospun silk fibroin/graphene oxide(SF/GO)nanofibrous and silk fibroin sponge-filled, respectively. Our results demonstrated that VEGF and GAS exhibited different release patterns in vitro which VEGF showed rapid release rate in the first few days while GAS was released slowly and continuously as encapsulated in liposomes. The scaffolds realized the combination of intraneural vascularization drugs and electrical stimulation effectively, leading to enhanced growth of RSC96 cells. Furthermore, the scaffolds could protect RSC96 cells in an inflammatory environment. [ABSTRACT FROM AUTHOR]

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Sponge‐like materials made from regenerated silk fibroin biopolymers are a tunable and advantageous platform for in vitro engineered tissue culture and in vivo tissue regeneration. Anisotropic, three‐dimensional (3D) silk fibroin sponge‐like scaffolds can mimic the architecture of contractile muscle. Herein, we use silk fibroin solution isolated from the cocoons of Bombyx mori silkworms to form aligned sponges via directional ice templating in a custom mold with a slurry of dry ice and ethanol. Hydrated tensile mechanical properties of these aligned sponges were evaluated as a function of silk polymer concentration (3% or 5%), freezing time (50% or 100% ethanol), and post‐lyophilization method for inducing crystallinity (autoclaving, water annealing). Hydrated static tensile tests were used to determine Young's modulus and ultimate tensile strength across sponge formulations at two strain rates to evaluate rate dependence in the calculated parameters. Results aligned with previous reports in the literature for isotropic silk fibroin sponge‐like scaffolds, where the method by which beta‐sheets were formed and level of beta‐sheet content (crystallinity) had the greatest impact on static parameters, while polymer concentration and freezing rate did not significantly impact static mechanical properties. We estimated the crystalline organization using molecular dynamics simulations to show that larger crystalline regions may be responsible for strength at low strain amplitudes and brittleness at high strain amplitudes in the autoclaved sponges. Within the parameters evaluated, extensional Young's modulus is tunable in the range of 600–2800 kPa. Dynamic tensile testing revealed the linear viscoelastic region to be between 0% and 10% strain amplitude and 0.2–2 Hz frequencies. Long‐term stability was evaluated by hysteresis and fatigue tests. Fatigue tests showed minimal change in the storage and loss modulus of 5% silk fibroin sponges for more than 6000 min of continuous mechanical stimulation in the linear regime at 10% strain amplitude and 1 Hz frequency. Furthermore, we confirmed that these mechanical properties hold when decellularized extracellular matrix is added to the sponges and when the mechanical property assessments were performed in cell culture media. We also used nano‐computed tomography (nano‐CT) and simulations to explore pore interconnectivity and tortuosity. Overall, these results highlight the potential of anisotropic, sponge‐like silk fibroin scaffolds for long‐term (>6 weeks) contractile muscle culture with an in vitro bioreactor system that provides routine mechanical stimulation. [ABSTRACT FROM AUTHOR]

Gel‐based adhesives show promising prospects in epidermal bioelectronics because of their potential applications in physiological signal collection and electrical stimulation. An ideal epidermal adhesive should exhibit robust adhesion for lamination and poor adhesion for easy peeling, in addition to strain‐insensitivity in electrical properties for motion‐artifact‐free physiological signal collection. Here, lignosulfonate‐derived organohydrogel adhesives with anisotropic and tunable adhesion, together with unprecedented strain‐insensitivity are synthesized. The organohydrogel exhibits a high interfacial toughness of 728 J m−2 on fresh porcine skin, while the adhesion can be screened by covering a denatured silk fibroin. An anisotropic adhesive with an adhesion heterogeneity is designed, showing a 14.2‐fold difference in adhesion strength along two different directions for on‐demand attachment and removal. The adhesive can transform into a highly porous structure, which has only a 3% resistance increase at 100% strain. The strain‐insensitivity of the adhesive lies in the strong interaction of ions and the 3D porous structure, which enables motion‐artifact‐free and high‐quality electrophysiological signal collection within the strain range of the human skin. The lignosulfonate‐derived on‐demand organohydrogel adhesive is expected to be used in epidermal bioelectronics, human‐machine interaction, metaverse, and beyond. [ABSTRACT FROM AUTHOR]

Nanofluidic systems due to their unique transport properties play a crucial role in a lot of applications ranging from water desalination to sensors. Over the past few years, considering the simple structure of two-dimensional materials, significant efforts have been devoted to designing synthetic membranes for ion transport. However, expensive fabrication methods such as lithography techniques and some shortcomings such as scale-up difficulty, low pore density, poor mechanical stability, and biocompatibility limit their practical application. Herein, we demonstrate a scalable hierarchically porous membrane with three-dimensional (3D) interconnected nanochannels which is based on the silk fibroin (SF) fiber biomass and modifying the nanofluidic channels by in situ growth of zeolitic imidazolate framework-67 (ZIF-67) nanoparticles on the fiber surfaces. The ZIF-67/SF membrane with 400 μm thickness is a 3D interconnected network with a large positively charged surface area (54 m2 g–1) containing 1–5 nm pores estimated from density functional theory modeling. Surface-charge-governed ion transport through the nanofluidic channels of the ZIF-67/SF membrane is systematically explored, and characteristic higher-than-bulk ion conductivity was observed at low concentrations (≤10–3 M) of monovalent electrolytes (KCl, NaCl, NaOH, and HCl). Moreover, the ZIF-67/SF is stable and fully functional at elevated temperatures up to 60 °C and maintains its structural and operational properties under acidic and basic conditions. [ABSTRACT FROM AUTHOR]

Silk fibroin (SF) extracted from silk is non-toxic and has excellent biocompatibility and biodegradability, making it an excellent biomedical material. SF-based soft materials, including porous scaffolds and hydrogels, play an important role in accurately delivering drugs to wounds, creating microenvironments for the adhesion and proliferation of support cells, and in tissue remodeling, repair, and wound healing. This article focuses on the study of SF protein-based soft materials, summarizing their preparation methods and basic applications, as well as their regenerative effects, such as drug delivery carriers in various aspects of tissue engineering such as bone, blood vessels, nerves, and skin in recent years, as well as their promoting effects on wound healing and repair processes. The authors expect SF soft materials to play an important role in the field of tissue repair. [ABSTRACT FROM AUTHOR]

In this study, we report the preparation and characterization of water-stable films with UV-shielding and good mechanical properties, exploiting the synergistic effect of regenerated silk fibroin and bamboo-derived cellulose. Silk fibroin (SF)/bamboo (B) hybrid films are achieved by solubilizing both silk and bamboo fibers in formic acid with added CaCl2. Infrared spectroscopy indicates that SF, when combined with bamboo, undergoes a conformational transition, providing evidence of an increase in SF crystallinity. Exploiting the intrinsic absorption of SF in the ultraviolet region, UV–Vis spectroscopy was used to assess the glass transition temperature (Tg) of SF/B films, showing a decrease in Tg by increasing the SF content. The addition of 10 wt% SF to the B matrix improved the elastic modulus by about 10% while conserving the strain at break with respect to the neat B films, increasing the UV shielding properties, while water absorption suggested the material's hydrophilic and swelling capacity even after one month. The hybrid films showed, under solar irradiation, a photoprotective behavior on keratinocyte human cells by increasing cellular viability. These findings may find potential applications in functional fabrics. [ABSTRACT FROM AUTHOR]

[Display omitted] Severe spinal cord injury (SCI) leads to dysregulated neuroinflammation and cell apoptosis, resulting in axonal die-back and the loss of neuroelectric signal transmission. While biocompatible hydrogels are commonly used in SCI repair, they lack the capacity to support neuroelectric transmission. To overcome this limitation, we developed an injectable silk fibroin/ionic liquid (SFMA@IL) conductive hydrogel to assist neuroelectric signal transmission after SCI in this study. The hydrogel can form rapidly in situ under ultraviolet (UV) light. The mechanical supporting and neuro-regenerating properties are provided by silk fibroin (SF), while the conductive capability is provided by the designed ionic liquid (IL). SFMA@IL showed attractive features for SCI repair, such as anti-swelling, conductivity, and injectability. In vivo , SFMA@IL hydrogel used in rats with complete transection injuries was found to remodel the microenvironment, reduce inflammation, and facilitate neuro-fiber outgrowth. The hydrogel also led to a notable decrease in cell apoptosis and the achievement of scar-free wound healing, which saved 45.6 ± 10.8 % of spinal cord tissue in SFMA@IL grafting. Electrophysiological studies in rats with complete transection SCI confirmed SFMA@IL's ability to support sensory neuroelectric transmission, providing strong evidence for its signal transmission function. These findings provide new insights for the development of effective SCI treatments. [ABSTRACT FROM AUTHOR]

Conventional antibiotic treatments for wound infections have the risk of developing microbial resistance, necessitating the search for innovative, alternative solutions like nanoparticles as advanced antibiotics. This work introduces a novel approach for managing acute and chronic wounds by creating an active wound dressing designed to both protect and eliminate bacteria from the injury site. We focused on the electroless deposition of large zinc oxide nanoparticles (ZnO NPs,), aiming for a particle size of around 200 nm to reduce cytotoxicity, onto electrospinned silk fibroin (SF) gauze. We assessed the biocompatibility and antimicrobial effectiveness of the ZnO NP-embedded silk dressing against gram-positive (Staphylococcus aureus) and gram-negative (Pseudomonas aeruginosa) bacteria. Our analysis indicates that incorporating ZnO nanoparticles into silk wound dressings maintains biocompatibility, achieving 70% cell viability while suppressing the growth of S. aureus and P. aeruginosa, particularly during the initial 24 h after application. By employing 200 nm particle sizes, we facilitated a significant release of zinc ions without producing harmful reactive oxygen species (ROSs) that could damage both bacteria and host tissues. These findings emphasize the therapeutic potential of bioresorbable bandages enhanced with large ZnO nanoparticles, presenting an innovative approach to clinical wound treatment. [ABSTRACT FROM AUTHOR]

Developing stimulus‐responsive materials (SRMs) with reversible, large, and reprogrammable multi‐responsiveness is crucial for soft actuators and intelligent devices, which remains challenging. In this study, regenerated silk fibroin with hierarchical structure is utilized to specially design a reprogrammable multi‐stimuli‐responsive protein film and versatile soft actuators. The freestanding fibroin films exhibit notable thermal contraction (−1383 ppm K−1) and humidity‐responsiveness that can be repeatedly regulated by easy post‐treatment with Ca2+ as desired. The actuating and regulating mechanisms involve reversible conformational change that is magnified into macroscopic deformations by hierarchical structure, and the roles of material structure and ambient conditions in determining actuating performances are analyzed based on thermodynamics. Driven by humidity gradient, the fibroin film demonstrates spontaneous flipping locomotion, self‐oscillation with tunable frequencies, bio‐butterfly wing flapping, and transformation from 2D to 3D structure. Moreover, reprogrammable deformations at specific regions are achieved in multi‐stimuli‐driven PET/fibroin film actuators owing to the straightforward Ca2+‐content‐based tunability of the responsiveness. The fibroin‐based actuators can be used as artificial muscles to drive the high‐frequency wing‐flapping of a bio‐dragonfly and soft gripper to grasp, lift, and transfer objects. The simple yet effective strategy presented herein provides valuable inspiration for designing advanced SRMs and soft actuators with reprogrammable multi‐responsiveness. [ABSTRACT FROM AUTHOR]

BACKGROUND: In the construction of guided bone regeneration membrane with biological function, a single material cannot meet the clinical needs due to its insufficient function, so the composite of multiple materials has become a trend of tissue repair engineering. OBJECTIVE: To prepare silk fibroin/bioactive glass composite fiber membranes by electrospinning technology, and to characterize the physicochemical properties and biocompatibility in vitro. METHODS: The solution of electrospinning was prepared by dissolving 0.8 g silk fibroin protein in 10 mL hexafluoro-isopropanol alcohol, and the nanofiber membrane of silk fibroin protein was prepared by electrospinning technology (denoted as SF fiber membrane). 0.1, 0.3, 0.5, and 0.8 g of bioactive glass were added to the electrospinning solution, and the silk fibroin/bioactive glass composite fiber membrane was prepared by electrospinning technology (recorded as SF/1BG, SF/3BG, SF/5BG, and SF/8BG fiber membrane in turn). The physicochemical properties and biocompatibility of five groups of fiber membranes were characterized. RESULTS AND CONCLUSION: (1) The scanning electron microscopy results showed that nanofibers of the prepared composite membrane were smooth, continuous and uniform and had no beaded structure. There was no obvious adhesion between the silk fibers, and they all showed random arrangement of disordered porous structures. The fiber diameter of the fiber membrane decreased after the addition of bioactive glass. Fourier infrared spectroscopy and X-ray diffraction detection results showed that the chemical structure of silk fibroin protein and bioactive glass in fiber membrane was stable. The water contact angles of SF, SF/1BG, SF/3BG, SF/5BG, and SF/8BG were 105.02°, 72.58°, 78.13°, 79.35°, and 72.50°, respectively. (2) Bone marrow mesenchymal stem cells were inoculated on five groups of fiber membranes. CCK-8 assay results showed that SF/1BG, SF/3BG, and SF/5BG fiber membranes could promote the proliferation of bone marrow mesenchymal stem cells compared with SF and SF/8BG. Live cell/dead cell staining showed that the cell vitality on the surface of the five groups of fiber membranes was better, and the number and distribution of cells on the surface of SF/5BG fiber membrane were more uniform. Rhodamine phalloidin staining and scanning electron microscopy exhibited that compared with SF fiber membrane, the SF/5BG fiber membrane was more favorable to the adhesion of bone marrow mesenchymal stem cells. Bone marrow mesenchymal stem cells were inoculated on the fiber membrane of the five groups for osteogenic induction differentiation, and the alkaline phosphatase activity of the SF/3BG and SF/5BG groups was higher than that of the other three groups (P < 0.05, P < 0.01, P < 0.001). Alizarin red staining showed that the formation of calcium nodules in fiber membrane increased after the addition of bioactive glass, and the formation of calcium nodules in the SF/5BG group was the most. (3) The results show that silk fibroin/bioactive glass composite fiber membrane has good biosafety and biocompatibility. [ABSTRACT FROM AUTHOR]

Highlights: Site-selective superassembly was used to synthesize a nanorobot with bionic rod-shaped head/hollow tail structure, exhibiting strong photothermal effect, high drug loading capacity, precise and controlled drug release, and excellent motility. Injectable regenerated silk fibroin (RSF) nanofibril hydrogels were developed via simple sonication, offering significant production, structural, and performance advantages. Nanorobot/thrombin (Thr)/RSF nanofibril hydrogels reduced intraoperative bleeding of hepatocellular carcinoma (HCC) spinal metastasis, provided starvation embolization, and prevented post-surgery recurrence. Nanorobot/Thr/RSF nanofibril hydrogels inhibited blood supply to residual tumors and reduced neovascularization, inhibiting post-surgery HCC spinal metastasis recurrence. Surgery remains the standard treatment for spinal metastasis. However, uncontrolled intraoperative bleeding poses a significant challenge for adequate surgical resection and compromises surgical outcomes. In this study, we develop a thrombin (Thr)-loaded nanorobot-hydrogel hybrid superstructure by incorporating nanorobots into regenerated silk fibroin nanofibril hydrogels. This superstructure with superior thixotropic properties is injected percutaneously and dispersed into the spinal metastasis of hepatocellular carcinoma (HCC) with easy bleeding characteristics, before spinal surgery in a mouse model. Under near-infrared irradiation, the self-motile nanorobots penetrate into the deep spinal tumor, releasing Thr in a controlled manner. Thr-induced thrombosis effectively blocks the tumor vasculature and reduces bleeding, inhibiting tumor growth and postoperative recurrence with Au nanorod-mediated photothermal therapy. Our minimally invasive treatment platform provides a novel preoperative therapeutic strategy for HCC spinal metastasis effectively controlling intraoperative bleeding and tumor growth, with potentially reduced surgical complications and enhanced operative outcomes. [ABSTRACT FROM AUTHOR]

Myocardial infarction (MI) is considered as a significant cause of death globally. Exosomes (EXOs) are essential for intercellular communication and pathophysiology of several cardiovascular diseases. Nevertheless, the short half-life and rapid clearance of EXOs leads to a lack of therapeutic doses delivered to the lesioned area. Therefore, an injectable silk fibroin and alginate (SF/Alg) composite hydrogel was developed to bind folate receptor-targeted EXOs (FA-EXOs) derived from H9C2 cells for the therapy of myocardial injury following myocardial infarction-ischemia/reperfusion (MI-I/R). The resulting composite exhibits a variety of properties, including adjustable gelation kinetics, shear-thinning injectability, soft and dynamic stability that adapts to the heartbeat, and outstanding cytocompatibility. After injected into the damaged rat heart, administration of SF/Alg + FA-EXOs significantly enhanced cardiac function as demonstrated by improved ejection fraction, fractional shortening and decreased fibrosis area. The results of real-time PCR and immunofluorescence staining show a remarkable up-regulation in the expression of proteins (CD31) and genes (VWF and Serca2a) related to the heart. Conversely, expression of fibrosis-related genes (TGF-β1) decreased significantly. Therefore, the obtained SF/Alg + FA-EXOs system remarkably enhanced the intercellular interactions, promoted cell proliferation and angiogenesis, and achieved an outstanding therapeutic effect on MI. [ABSTRACT FROM AUTHOR]

Based on the principle of additive manufacturing, the innovative technology, 3D bioprinting, can realize the rapid prototyping of bionic functional tissues or artificial organs by accurately positioning and assembling bioinks containing biological materials and cell units, bringing unprecedented opportunities to the medical field. Its application prospect is very broad, and it is expected to solve many medical problems and benefit human health. In the complex process of 3D bioprinting, the choice of bio-ink materials is crucial. It is the key to meeting the strict requirements of bio- safety, fineness and stability of 3D bioprinted bionic structures. Silk fibroin stands out as a potential biological 3D printing material due to its high biocompatibility, controllable biodegradability and adjustable mechanical properties and many other excellent properties. It is obtained by dissolving silk and dialysis, and then products that meet the requirements of different applications, such as hydrogels, films and sponges are prepared through physical or chemical crosslinking. Among the many cross-linking methods, compared with conventional physical cross-linking, thermochemical cross-linking and bioenzyme-catalyzed cross-linking, photocrosslinked fibroin hydrogel technology shows unique advantages. The photocrosslinked fibroin hydrogel technology has the characteristics of fast reaction rate, and can complete the crosslinking process in a short time, which greatly improves the work efficiency. Its conditions are milder and less damaging to biological materials and cells, helping to maintain their biological activity. At the same time, the spatiotemporal controllability makes it possible to precisely control the position and time of the crosslinking, thus achieving more fine and complex structures. In addition, the advantage of fewer by-products also reduces the potential harm to the environment and organisms. In this paper, the optical crosslinking technology of silk fibroin materials is the main line to carry out in-depth research and discussion. Based on rheological properties, the printing method suitable for photocrosslinked silk fibroin 3D printing was introduced. Through the in-depth analysis of the rheological properties of materials, the printing parameters can be optimized and the printing precision and quality can be improved. From the perspective of photocrosslinking reactivity, the photosensitive modification method of fibroin and the photoinduced crosslinking mechanism of fibroin were discussed, which is of great significance for understanding and mastering the photocrosslinking process and further improving and optimizing the technology. From the perspective of biocompatibility, the development of irradiation light source and photoinitiator was introduced. Good biocompatibility is an important prerequisite for the application of biological materials in the medical field, and the selection of appropriate irradiation light source and photoinitiator can guarantee this characteristic. Finally, the application of silk fibroin and its composite inks with synthetic and natural polymer materials in the field of photocrosslinked bioprinting was summarized, and the challenges in the preparation, development and application of photocrosslinked silk protein bioprinting were discussed. [ABSTRACT FROM AUTHOR]

Skin is the largest protective tissue of the body and is at risk of damage. Hence, the design and development of wound dressing materials is key for tissue repair and regeneration. Although silk fibroin is a known biopolymer in tissue engineering, its degradation rate is not correlated with wound closure rate. To address this disadvantage, we mimicked the hierarchical structure of skin and also provided antibacterial properties; a hydrogel with globular structure consisting of silk fibroin, pluronic F127, and curcumin was developed. In this regard, the effect of pluronic and curcumin on the structural and mechanical properties of the hydrogel was studied. The results showed that curcumin affected the particle size, crystallinity, and ultimate elongation of the hydrogels. In vitro assays confirmed that the hydrogel containing curcumin is not cytotoxic while the diffused curcumin and pluronic provided a considerable bactericidal property against Methicillin-resistant Staphylococcus aureus. Interestingly, presence of pluronic caused more than a 99% reduction in planktonic and adherent bacteria in the curcumin-free hydrogel groups. Moreover, curcumin improved this number further and inhibited bacteria adhesion to prevent biofilm formation. Overall, the developed hydrogel showed the potential to be used for skin tissue regeneration. [ABSTRACT FROM AUTHOR]

Bioscaffolds, which promote cell regeneration and restore tissues' functions, have emerged as significant need in clinic. The hybrid of several biomaterials in a bioscaffold renders clinically advanced and relevant properties for applications yet add challenges in cost efficiency, production, and clinical investigation. This study proposes a facile and sustainable method to formulate a triple-hybrid bioscaffold based on Vietnamese cocoon origin Silk Fibroin, Chitosan, and nano-Biphasic Calcium Phosphates (nano-BCP) that can be easily molded, has high porosity (55–80%), and swelling capacity that facilitates cell proliferation and nutrient diffusion. Notably, their mechanical properties, in particular compressive strength, can easily be tuned in a range from 50 – 200 kPa by changing the amount of nano-BCP addition, which is comparable to the successful precedents for productive cell regeneration. The latter parts investigate the biopharmaceutical properties of a representative bioscaffold, including drug loading and release studies with two kinds of active compounds, salmon calcitonin and methylprednisolone. Furthermore, the bioscaffold is highly biocompatible as the results of hemocompatibility and hemostasis tests, as well as ovo chick chorioallantoic membrane investigation. The findings of the study suggest the triple-hybrid scaffold as a promising platform for multi-functional drug delivery and bone defect repair. [Display omitted] [ABSTRACT FROM AUTHOR]

Melanoma is one of the most aggressive forms of skin cancer, which is characterized by metastasis and poor prognosis due to the limited effectiveness of current therapies and the toxicity of conventional drugs. For this reason and in recent years, one of the most promising strategies in the treatment of this form of cancer is the use of drug delivery systems as carriers capable of conveying the therapeutic agent into the tumor microenvironment, thus preventing its degradation and improving its safety and effectiveness profiles. In the present work, microparticles based on silk fibroin and epifibroin 0039, silk-derived proteins loaded with idebenone, were created, which act as therapeutic carriers for topical use in the treatment of melanoma. The resulting particles have a spherical shape, good loading efficiency, and release capacity of idebenone. Efficacy studies have demonstrated a reduction in the proliferation of COLO-38, melanoma tumor cells, while safety tests have demonstrated that the microparticles are not cytotoxic and do not possess prosensitizing activity. Notably, transdermal release studies revealed that all particles released idebenone over more days. The analysis of the stimulatory markers of the proinflammatory process, CD54 and CD86, did not show any increase in expression, thus confirming the absence of potential prosesensitization effects of the silk fibroin-based particles. The research, therefore, found that idebenone-loaded silk protein microparticles could effectively reduce the proliferation of melanoma cells without cytotoxicity. This indicates the promise of a safe and effective treatment of melanoma. [ABSTRACT FROM AUTHOR]

By promoting tissue regeneration, porous nano‐scaffolds offer improved chances for the maintenance, repair, and enhancement of damaged tissues and organ functioning. In this study, the nanosilica extract obtained from the agricultural waste, that is, rice husk after surface modification shows higher hydrophobicity in the hexamethyldisilazane and methyltrimethoxysilane‐modified nanosilica and hydrophilic nature in 3‐aminopropyl triethoxysilane‐modified nanosilica. Fourier transform infrared spectroscopy results reveal the functional groups exist in the scaffold and its surface morphology was evaluated by Field emission scanning electron microscope/energy dispersive X‐ray analysis which shows a cross‐network structure that could impart the proper cell adhesion. The presence of amorphous nanosilica in ultrapure form was confirmed using X‐ray diffraction analysis where a broad peak was obtained in the range of 15°–40°. The crystallization phase of the hybrid scaffold shows 2θ values obtained at 22.6°, 28.7°, and 40.6°. The graph thus obtained confirms that the material used is 3‐aminopropyl‐triethoxysilane‐modified silk/silica nanocomposite. The decomposition rates and temperature of the composite were analyzed using the thermogravimetry/differential thermal technique. The antibacterial activity of the hybrid scaffolds and silk and silica shows the metabolic pathways were not disrupted for both Gram‐positive and ‐negative microbes. Cell cytotoxicity analysis proved that the electrospun hybrid scaffold was nontoxic to L929 cells and promoted cell adhesion and growth. The cells were highly proliferated onto the surface layers in a regular systematic pattern thus proving that these scaffolds were suitable for bone regeneration applications. Hence these economically viable scaffolds turn to be biocompatible and are promising as a novel product for cell culture regneration realted to therapy. [ABSTRACT FROM AUTHOR]

Silk fibroin is highly susceptible to damage during the extraction process. To address this issue, this study proposes an integrated degumming solution that uses a composite system of Na2CO3 and the surfactant SDS (sodium dodecyl sulfate), combined with ultrasonic treatment. Silk fibroin fibers treated with this method exhibit a smoother and more even surface, with markedly less fiber damage. Compared to the traditional 100 °C alkaline degumming (30 min complete degumming), this scheme completes degumming in only 10 min at 75 °C. Nanofibrous membranes were prepared from these degummed fibers using electrospinning technology, and their β-sheet crystalline content increased to 49.58% after ethanol treatment, along with high tensile strength (5.27 MPa) and elongation at break (123.49%). Over a 5-day cell culture period, the membranes have supported cell adhesion, spreading and proliferation, demonstrating excellent cytocompatibility. These research findings provide a novel solution for the production of high-performance silk fibroin nanofibrous membranes and are expected to advance the application and development of silk fibroin materials in the biomedical field. [ABSTRACT FROM AUTHOR]

Due to the clinical similarities between pulmonary embolism (PE) and myocardial infarction (MI), physicians often encounter challenges in promptly distinguishing between them, potentially missing the critical window for the correct emergency response. This paper presents a biosensor, termed the PEMI biosensor, which is designed for the identification and quantitative detection of pulmonary embolism or myocardial infarction. The surface of the working electrode of the PEMI biosensor was modified with graphene oxide and silk fibroin to immobilize the mixture of antibodies. Linear sweep voltammetry was employed to measure the current-to-potential mapping of analytes, with the calculated curvature serving as a judgment index. Experimental results showed that the curvature exhibited a linear correlation with the concentration of antigen FVIII, and a linear inverse correlation with the concentration of antigen cTnI. Given that FVIII and cTnI coexist in humans, the upper and lower limits were determined from the curvatures of a set of normal concentrations of FVIII and cTnI. An analyte with a curvature exceeding the upper limit can be identified as pulmonary embolism, while a curvature falling below the lower limit indicates myocardial infarction. Additionally, the further the curvature deviates from the upper or lower limits, the more severe the condition. The PEMI biosensor can serve as an effective detection platform for physicians. [ABSTRACT FROM AUTHOR]

Purpose: To compare different methods of preparing silk fibroin hydrogels, then summarize the applications of silk fibroin hydrogel‐based scaffolds in skin regeneration and finally discuss about future prospects to inspire people interested in this field. Methods: A narrative review of the relevant papers was conducted. Notably, for applications in skin regeneration, this review provides a categorized summary and discussion of studies from the past decade. Results: Silk fibroin is a naturally occurring, biocompatible biomaterial that is easily producible. Thanks to its exceptional processability, silk fibroin has found diverse applications in skin regeneration. These applications encompass sponges, fiber fabrics, thin films, and hydrogels. Hydrogels, in particular, are noteworthy due to their water‐containing network structure, closely resembling natural tissues. They provide a biomimetic three‐dimensional growth environment for cells and have the capacity to incorporate growth factors. Consequently, there are abundant studies of silk fibroin hydrogel‐based scaffolds in skin regeneration. Besides, some commercialized medical devices are also made of silk fibroin. Conclusion: Silk fibroin hydrogel could be prepared with multiple methods and it is widely used in constructing scaffolds for efficient skin regeneration. In the future, silk fibroin hydrogel‐based skin scaffolds could be more biomimetic and smart. [ABSTRACT FROM AUTHOR]

The main antioxidant polyphenol compounds in the mango (Mangifera indica L.) leaf extract are susceptible to environmental degradations. Thus, in biomedical applications, the mango leaf extract is commonly encapsulated in a carrier. However, most studies employed the synthetic carrier materials that could affect the human health, and the complicated formulation procedure that could hinder the scalability. Therefore, this work, for the first time, explored the use of silk fibroin (an FDA-approved biomaterial), in nanoparticles platform, to encapsulate and deliver the mango leaf extract, utilizing the simple coacervation preparation method. Initially, the mango leaf ethanolic extract was obtained through maceration, resulting in a total phenolic content of 76.39 ± 0.14 mg GAE/g DPW and a notably high antioxidant activity (IC50 = 6.872 ± 0.512 µg/mL). Subsequently, silk fibroin nanoparticles loaded with the extract were developed by the coacervation technique. Depending on the fibroin content, these nanoparticles exhibited an appropriate size range of 500-800 nm with narrow size distributions, a spherical shape with smooth surfaces, a dominant silk-II crystalline structure, a drug entrapment efficiency exceeding 70%, and retained the main biomarker mangiferin. Moreover, the phenolic-compounds release profiles from the particles followed the three-step process, the first burstrelease step, the second sustained-release step, and the third degradation step. The particles were also non-toxic to the erythrocytes and the human embryonic kidney HEK-293 cell line. Lastly, the 2,2-diphenyl-1-picrylhydrazyl (DPPH) assay demonstrated that the antioxidant activity of the mango leaf extract was preserved within the extract-loaded nanoparticles. The results suggested that the silk fibroin nanoparticles could be a potential platform to effectively encapsulate and deliver the mango leaf extract for biomedical purposes. [ABSTRACT FROM AUTHOR]

Bioactive agents have demonstrated regenerative potential for cell-free bone tissue engineering. Nevertheless, certain challenges persist, including ineffective delivery methods and confined therapeutic potency. Here, we demonstrated that the biomimetic calcium phosphate coating system (BioCaP) could effectively uptake and slowly release the incorporated bioactive agents compared to the surface absorption system via osteoclast-mediated degradation of BioCaP coatings. The release kinetics were determined as a function of time. The release rate was stable without remarkable burst release during the first 1 day, followed by a sustained release from day 7 to day 19. Then, we developed the bi-functional BioCaP-coated silk fibroin scaffolds enabling the effective co-delivery of TGF-β3 and BMP-2 (SFI-T/SFI-B) and the corresponding slow release of TGF-β3 and BMP-2 exhibited superior potential in promoting chondrogenesis and osteogenesis without impairing cell vitality in vitro. The SFI-T/SFI-B scaffolds could improve cartilage and bone regeneration in 5 × 4 mm rabbit osteochondral (OC) defect. These findings indicate that the biomimetic calcium-phosphate coated silk fibroin scaffolds with slowly co-released TGF-β3 and BMP-2 effectively promote the repair of OC defects, hence facilitating the future clinical translation of controlled drug delivery in tissue engineering. [ABSTRACT FROM AUTHOR]

Background: With the rapid growth of the ageing population, chronic diseases such as osteoarthritis have become one of the major diseases affecting the quality of life of elderly people. The main pathological manifestation of osteoarthritis is articular cartilage damage. Alleviating and repairing damaged cartilage has always been a challenge. The application of cartilage tissue engineering methods has shown promise for articular cartilage repair. Many studies have used cartilage tissue engineering methods to repair damaged cartilage and obtained good results, but these methods still cannot be used clinically. Therefore, this study aimed to investigate the effect of incorporating nerve growth factor (NGF) into a silk fibroin (SF)/chitosan (CS) scaffold containing bone marrow-derived mesenchymal stem cells (BMSCs) on the repair of articular cartilage defects in the knees of rabbits and to explore the possible underlying mechanism involved. Materials and methods: Nerve growth factor-loaded sustained-release microspheres were prepared by a double emulsion solvent evaporation method. SF/CS scaffolds were prepared by vacuum drying and chemical crosslinking. BMSCs were isolated and cultured by density gradient centrifugation and adherent culture. NGF-SF/CS-BMSC composites were prepared and implanted into articular cartilage defects in the knees of rabbits. The repair of articular cartilage was assessed by gross observation, imaging and histological staining at different time points after surgery. The repair effect was evaluated by the International Cartilage Repair Society (ICRS) score and a modified Wakitani score. In vitro experiments were also performed to observe the effect of different concentrations of NGF on the proliferation and directional differentiation of BMSCs on the SF/CS scaffold. Results: In the repair of cartilage defects in rabbit knees, NGF-SF/CS-BMSCs resulted in higher ICRS scores and lower modified Wakitani scores. The in vitro results showed that there was no significant correlation between the proliferation of BMSCs and the addition of different concentrations of NGF. Additionally, there was no significant difference in the protein and mRNA expression of COL2a1 and ACAN between the groups after the addition of different concentrations of NGF. Conclusion: NGF-SF/CS-BMSCs improved the repair of articular cartilage defects in the knees of rabbits. This repair effect may be related to the early promotion of subchondral bone repair. [ABSTRACT FROM AUTHOR]

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Conventional electrodes are of significant challenges in acquiring bioelectric signals concerning a high signal‐to‐noise ratio (SNR), long‐term and comfortable wear, low motional noise, etc. To resolve these issues, silk fibroin (SF) materials are adopted to create flexible microneedle array electrodes (FMNA‐electrode) based on meso‐engineering. The research approaches involve constructing flexible conductive electrodes from non‐conductive and bristle‐regenerated SF. By controlling the molecular interchain nucleation in the refolding process of unfolded regenerated SF molecules, this goal can be achieved. In this process, silver nanowires (Ag NWs) are adopted as meso‐dopants to reconstruct the meso‐electronic structure of SF films at the surface, while polyurethane (PU) is selected as molecular templates to facilitate the molecular nucleation in the refolding of SF molecules. This leads to the occurrence of SF‐PU meso‐hybridization, giving rise to more flexible meso‐hybridized SF. The SF‐PU FMNA‐electrode demonstrates biocompatibility, comfort wearing, long‐term monitoring capability, low motional noise, and a high SNR in the application of collecting ECG, EMG, and EOG signals. The outperformance of SF‐PU FMNA‐electrode is superior to both conventional wet and commercially available dry electrodes, paving the way for the next generation of flexible, skin‐friendly, durable, and high‐performance health monitoring devices and brain‐machine interfaces. [ABSTRACT FROM AUTHOR]

In the present study, a method is proposed for preparing novel ductile‐sticky materials that can be used as bone void fillers using hydrolyzed wool‐keratin (WK) and silk fibroin (SF). This methodology uses citric acid as a cross‐linking agent in preparing keratin paste (KP) owing to its non‐toxicity and plasticizing properties. The Keratin paste‐silk fibroin structure (KPSF) is obtained by adding SF, which possesses biocompatible and superior mechanical properties. Methanol treatment is employed on the KPSF mixture to convert the Silk I structure in the SF to Silk II, resulting in a water‐insoluble and tightly packed proteinaceous structure. The physicochemical properties of both bioscaffolds are investigated and discussed in detail by comparison. Based on the findings, the presence of SF in the KPSF structure contributed to properties such as flexibility and porosity. In ovo CAM analysis reveals that both materials exhibit proangiogenic properties and are biocompatible. KP and KPSF bioscaffolds can be converted into ductile‐sticky forms by adding water. It believes that these forms can easily apply to bone defect areas, particularly cavitary bone defects. Furthermore, KPSF bioscaffolds, with better mechanical properties, can be considered candidates for use in non‐load‐bearing bone tissue engineering applications. [ABSTRACT FROM AUTHOR]

The creation of functional hydrogels with robust load‐bearing capacity adaptable to complex tissue regeneration remains challenging. Silk fibroin (SF) is a natural biomaterial with excellent mechanical strength and cell adhesion capacity, possessing tremendous potential to solve the aforementioned dilemma. The excellent biodegradability and biocompatibility and the molecular structure with multiple modifiable moieties provide opportunities for the injectability and multifunctionality of hydrogels. Furthermore, the incorporation of other polymers or active ingredients can improve the basic properties, confer biological activities and pharmacological effects, and provide the prerequisites for hydrogels to fulfill specific requirements. Therefore, SF‐based hydrogels are widely applied in tissue repair and regeneration, especially in bone, skin, nerve, liver, myocardium, and cornea, which have effectively addressed the challenges of scaffolds' lack of cell adhesion sites, excessive degradation, as well as the lack of efficient, long‐lasting antimicrobial properties. This review outlines the properties of SF, discusses the types of materials commonly used in the preparation of hydrogels and their characteristics, and describes the current construction methods of SF hydrogels. Simultaneously, recent advancements in applying SF‐based multifunctional hydrogels within biological tissues are explored, with a focus on their role in tissue repair, highlighting the repair mechanism of SF based on bone and skin. [ABSTRACT FROM AUTHOR]

Silk fibroin hydrogels are extensively explored for tissue engineering and regenerative medicine as an artificial extracellular matrix (ECM) that can support tissue growth. However, the nanometer pore size of hydrogels limits adequate cell, tissue, and vascular infiltration. Microgel scaffolds are an emerging class of microporous biomaterials formed by annealing small microscale hydrogels (microgels) into a 3D construct. In this work, silk microgels are generated using a microfluidic device that allows tuning of the microgel diameter (100–400 µm) and are stabilized via visible light‐initiated photo‐crosslinking of native tyrosine residues in silk. Microgels are then covalently annealed using silk solution as glue and the same cytocompatible visible light‐initiated crosslinking to form microgel scaffolds. Unlike the nano‐porosity of bulk photo‐crosslinked silk hydrogels, the microgel scaffolds have an average pore diameter of 29 ± 17 or 192 ± 81 µm depending on the microgel size, with enhanced mechanical properties compared to bulk hydrogels. This microporosity supports enhanced cell spreading and proliferation in vitro and increases scaffold remodeling in vivo, encouraging improved tissue infiltration and matrix deposition. The microgel size and material format also affect inflammatory responses in vivo. This work demonstrates that silk microgels and microgel scaffolds are promising candidates for tissue engineering and regenerative medicine applications. [ABSTRACT FROM AUTHOR]

Skin injuries are common problems and large skin defects or infected skin needs extra attention that make the researchers find new solutions. Herein, a novel biocompatible, biodegradable antibacterial scaffold containing gelatin, TiO2, polycaprolactone, and silk fibroin loaded with different ratios of curcumin (0.5, 1, and 1.5% wt.) was fabricated with electrospinning technique and was tested with various in vitro tests. The cellular investigations (cell adhesion, cell viability, and in vitro migration test) and antibacterial assay revealed the higher efficiency of the scaffold with 1% wt. curcumin and further investigation were performed on this scaffold. The morphological observation confirmed the nanofibrous structure of the scaffold, with 0.10 ± 0.015 μm average fiber diameter. This scaffold showed hydrophilic nature with high swelling ratio absorption and 76.45 ± 5.19% degradation ratio after 2 weeks. Also, it could provide adequate mechanical properties for skin regeneration. The drug-releasing investigation revealed Cur's controlled release over 48 h. Therefore, this biocompatible and antibacterial scaffold showed high potential for treating skin injuries and is suggested for future in vivo studies. [ABSTRACT FROM AUTHOR]

Wound dressings play a crucial role in wound treatment. Silk fibroin fiber membranes prepared via electrostatic spinning have generated medical wound dressings, exhibiting good biocompatibility with hemostatic, antimicrobial, and pro-healing properties. A pH-responsive ZnS/SF composite fiber membrane was prepared by loading zinc sulfide (ZnS) nanoparticles into a silk fibroin fiber membrane via in situ polymer matrix growth. The composite fiber membranes produced under the optimized conditions were successfully loaded with nanoscale ZnS particles. They had a dense reticular structure and high-water absorption with good biocompatibility and hemostatic properties. Upon exposure to an acidic microenvironment at the wound site, ZnS reacted with H+, giving a sustained release of hydrogen sulfide (H2S) and zinc ions (Zn2+), possessing strong bactericidal activity and pro-cell migration effects, facilitating angiogenesis. The composite fiber film is effective in helping to further promote wound healing when it is used as a wound dressing. This pH-responsive multifunctional ZnS/SF composite fiber membrane has potential applications in medical wound dressings. [ABSTRACT FROM AUTHOR]

The high crystallinity and sophisticated hierarchical architecture of native animal silk endow it with comprehensive mechanical properties that are superior to those of most synthetic fibers. However, these features also make the direct exfoliation of silk nanofibrils (SNFs) highly challenging. On the other hand, silk‐based materials prepared by conventional method (i.e., through silk fibroin aqueous solution) are usually weak, so the preparation methods based on SNFs have attracted much attention in recent years. Herein, a facile and environmentally friendly route is developed to directly exfoliate SNFs from natural Bombyx mori silkworm silk via ammonium persulfate oxidation followed by ultrasonication. The obtained SNFs have a high yield (nearly 40%) and are well dispersed in water in a wide pH range, so they can act as a good starting material to prepare subsequent silk‐based materials. The main application of the SNFs demonstrated in this article is a curcumin (Cur)/SNFs hydrogel as wound dressing. In vivo experimental results show that the Cur/SNFs hydrogel significantly enhanced the healing rate of wounds on diabetic mice. Therefore, the preparation method developed in this study provides an efficient way to produce SNFs, which have great potential for a wide range of applications, including as wound dressings for diabetics. [ABSTRACT FROM AUTHOR]

In this paper, wound dressing materials made of silk fibroin (SF) and transgenic SF with Arg-Gly-Asp motifs (TG-RGD SF) were developed. Initially, an animal evaluation experiment with mice to demonstrate the usefulness of SF film as a wound dressing was performed. The amorphous SF film was shown to promote the formation of granulation tissue and neovessels in the dermis, leading to skin regeneration. As a result, amorphous SF film is suitable for use as a wound dressing materials. Then, the SF- Human umbilical vein endothelial cells signaling pathway was determined by cell proliferation assay with pharmacological inhibitors. Subsequently, a mice evaluation experiment to assess the promotion of healing effects using TG-RGD SF was conducted and the results were compared with those obtained using SF. In the wound area evaluation and the quantitative evaluation of granulation tissue formation, the TG-RGD SF film promoted dermis regeneration more than the SF film. [ABSTRACT FROM AUTHOR]

Due to the good extracellular matrix biomimetic properties, silk fibroin (SF) hydrogels have been extensively concerned and studied in the fields of tissue engineering scaffold and 3D cell culture. The most widely used ones among them are mild chemical crosslinked SF hydrogels. However, as the inevitable movement and self-assembly of hydrophobic segments of silk fibroin in such hydrogels, the conformation of silk fibroin transforms from random coil to the β-sheet conformation with lower energy level, which will dynamically change the basic characteristics (such as the stiffness and pore size) of the hydrogels. Consequently, unknown and non-negligible impacts on the biomedical application of the hydrogel were induced. Based on this perspective, the SF hydrogel, which was crosslinked by horseradish peroxidase in a mild manner, was chosen as model materials. The strategy of changing related crosslinking density was used to successfully regulate the rate of protein conformational transition in SF hydrogels. At the same time, the effect of protein conformational transition rate in such an SF hydrogel on the proliferation of cells adhering to its surface was investigated. Results showed that the rate of protein conformational transition in corresponding hydrogels was inversely related to the crosslinking density. The lower the crosslinking density was, the faster the conformational transition was. Meanwhile, the proliferation of mouse embryonic fibroblasts (NIH3T3) cells on the hydrogel surface was generally positively correlated with the rate of protein conformational transition in corresponding hydrogels. However, as it also existed the effects of the accompanied initial crosslinking densities, the final trend was that the total number of cells on hydrogels with medium conformational transition rate was relatively low, and that on hydrogels with the fastest conformational transition rate was relatively high. [ABSTRACT FROM AUTHOR]

Silk fibroin interactions with metallic surfaces can provide utility for medical materials and devices. Toward this goal, titanium alloy (Ti6Al4 V) was covalently grafted with polyacrylamide via electrochemically reducing 4‐nitrobenzene diazonium salt in the presence of acrylamide. Analysis of the modified surfaces with FT‐IR spectra, SEM and AFM were consistent with surface grafting. Functionalised titanium samples with a silk fibroin membrane, with and without impregnated therapeutics, were used to assess cytocompatibility and drug delivery. Initial cytocompatibility experiments using fibroblasts showed that the functionalised samples, both with and without silk fibroin coatings, supported significant increases between 72–136 % in cell metabolism, compared to the controls after 7 days. A 7‐days release profiling showed consistent bacterial inhibition through gentamicin release with average inhibition zones of 239 mm2. Over a 5‐week period, silk fibroin coated samples, both with and without growth factors, supported better human mesenchymal stem cell metabolism with increases reaching 1031 % and 388 %, respectively, compared to samples without the silk fibroin coating with. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Silk fibroin (SF) microparticles were administered in the diet of gilthead seabream with or without experimental skin wounds to study the effects on cellular immunity and liver. A commercially available diet was enriched with varying amount of SF: 0, 50 and 100 mg kg−1 (representing the control, SF50 and SF100 diets respectively). The animals were fed for 30 days and half of them were sampled. Similar experimental wounds were then performed on the rest of fish, and they continued to be fed the same diet. At 7 days post‐wounding, samples were taken from the wounded fish. Cellular immunity was studied on head kidney leucocytes (phagocytosis, respiratory and peroxidase content) and liver status (histological study and gene expression) were studied. Our results showed that experimental wounds affect both cellular immunity (by decreasing leucocyte respiratory burst and peroxidase activity) and altered liver histology (by inducing vascularisation and congestion of blood vessels). In addition, it influences the expression of genes that serve as markers of oxidative stress, endoplasmic reticulum stress and apoptosis. The highest dose of SF (SF100) increased the phagocytic capacity of leucocytes the most, as well as the expression of genes related to blood vessel formation in the liver. Furthermore, increased expression of antioxidant genes (cat and gsr) and decreased expression of genes related to reticulum endoplasmic stress (grp94 and grp170) and apoptosis (nos and jnk) were detected in these fish fed with SF100 and wounded. In conclusion, fed fish with SF100 had many beneficial effects as cellular immunostimulant and hepatoprotection in wounded fish. Its use could be of great interest for stress management in farmed fish conditions. [ABSTRACT FROM AUTHOR]

Zeolitic imidazolate frameworks (ZIFs) are an important subclass of metal-organic frameworks (MOFs) with zeolite-type topology, which can be fabricated under ambient synthesis conditions. However, the applications of ZIFs are commonly limited due to the weak hydrostability of their metal–ligand coordination bonds, particularly under humid and aqueous conditions. In this work, as an example, the hydrolysis behaviours of ZIF-L with a special focus on ZIF-L coatings were tested at aqueous conditions with a wide range of pHs to systematically study and fundamentally understand their structural stability and degradation mechanism. Pristine ZIF-L powder and ZIF-L coatings were severely damaged after only 24 h in aqueous media. Interestingly, the ZIF-L coatings showed two distinct hydrolyzation pathways regardless of pH conditions, exhibiting either a ring-shaped etching or unfolding behaviours. While the ZIF-L powders were hydrolyzed almost identically across all pH conditions. With this new understanding, a facile silk fibroin (SF) protein modification method was developed to enhance the hydrostability of ZIF-L coatings in aqueous media. The effect of protein concentration on surface coating was systemically studied. ZIF-L coating retained its surface morphology after soaking in water and demonstrated switchable super wetting properties and superior separation performance for oil/water mixture. As a result, the quick SF protein modification significantly enhanced the stability of ZIF-L coatings under various pHs, while retaining their switchable wetting property and excellent separation performance. [ABSTRACT FROM AUTHOR]

Objective: Electrospun nanofibers exhibit potential as scaffolds for articular cartilage tissue regeneration. This study aimed to fabricate electrospun polycaprolactone (PCL)/silk fibroin (SF) composite nanofiber scaffolds and to explore performance of the scaffolds for articular chondrocyte regeneration. Methods: By altering material composition and preparation methods, three types of nanofiber scaffolds were effectively fabricated, including randomly oriented PCL (RPCL) nanofiber scaffold, randomly oriented PCL/SF (RPCL/SF) nanofiber scaffold, and aligned PCL/SF (APCL/SF) nanofiber scaffold. Physiochemical analyses were performed to determine mechanical properties and surface hydrophilicity of the nanofiber scaffolds. In vitro studies were conducted to investigate performance of the scaffolds on articular chondrocyte proliferation, gene expression and glycosaminoglycan secretion. Cytoskeleton staining was used to observe the arrangement of chondrocytes along the direction of the fibers and their elongation along the fiber arrangement. Results: The physicochemical analysis demonstrated that the APCL/SF nanofiber scaffold exhibited improved mechanical properties and surface hydrophilicity compared to the RPCL and RPCL/SF nanofiber scaffolds. Furthermore, the in vitro cell culture studies confirmed that the APCL/SF nanofibers could significantly promote articular chondrocyte proliferation, type II collagen (COL-II) gene expression, and glycosaminoglycan secretion compared to the RPCL and RPCL/SF nanofiber scaffolds. Additionally, cytoskeletal staining displayed that the APCL/SF nanofiber scaffold promoted the elongation of articular chondrocytes in the direction of parallel fiber alignment. Conclusion: The APCL/SF nanofiber scaffold exhibited promising potential as a composite scaffold for articular cartilage regeneration. [ABSTRACT FROM AUTHOR]

Three-dimensional (3D) bioprinting technology enables the controlled deposition of cells and biomaterials (i.e., bioink) to easily create complex 3D biological microenvironments. Silk fibroin (SF) has recently emerged as a compelling bioink component due to its advantageous mechanical and biological properties. This study reports on the development and optimization of a novel bioink for extrusion-based 3D bioprinting and compares different bioink formulations based on mixtures of alginate methacrylate (ALMA), gelatin and SF. The rheological parameters of the bioink were investigated to predict printability and stability, and the optimal concentration of SF was selected. The bioink containing a low amount of SF (0.002% w/V) was found to be the best formulation. Light-assisted gelation of ALMA was exploited to obtain the final hydrogel matrix. Rheological analyses showed that SF-enriched hydrogels exhibited greater elasticity than SF-free hydrogels and were more tolerant to temperature fluctuations. Finally, MG-63 cells were successfully bioprinted and their viability and proliferation over time were analyzed. The SF-enriched bioink represents an excellent biomaterial in terms of printability and allows high cell proliferation over a period of up to 3 weeks. These data confirm the possibility of using the selected formulation for the successful bioprinting of cells into extracellular matrix-like microenvironments. [ABSTRACT FROM AUTHOR]

Silk proteins have been highlighted in the past decade for tissue engineering (TE) and skin regeneration due to their biocompatibility, biodegradability, and exceptional mechanical properties. While silk fibroin (SF) has high structural and mechanical stability with high potential as an external protective layer, traditionally discarded sericin (SS) has shown great potential as a natural-based hydrogel, promoting cell–cell interactions, making it an ideal material for direct wound contact. In this context, the present study proposes a new wound dressing approach by developing an SS/SF bilayer construct for full-thickness exudative wounds. The processing methodology implemented included an innovation element and the cryopreservation of the SS intrinsic secondary structure, followed by rehydration to produce a hydrogel layer, which was integrated with a salt-leached SF scaffold to produce a bilayer structure. In addition, a sterilization protocol was developed using supercritical technology (sCO2) to allow an industrial scale-up. The resulting bilayer material presented high porosity (>85%) and interconnectivity while promoting cell adhesion, proliferation, and infiltration of human dermal fibroblasts (HDFs). SS and SF exhibit distinct secondary structures, pore sizes, and swelling properties, opening new possibilities for dual-phased systems that accommodate the different needs of a wound during the healing process. The innovative SS hydrogel layer highlights the transformative potential of the proposed bilayer system for biomedical therapeutics and TE, offering insights into novel wound dressing fabrication. [ABSTRACT FROM AUTHOR]

The paper highlights how significant characteristics of liver can be modeled in tissue-engineered constructs using unconventional scaffolds. Hepatic lobular organization and metabolic zonation can be mimicked with decellularized plant structures with vasculature resembling a native-hepatic lobule vascular arrangement or silk blend scaffolds meticulously designed for guided cellular arrangement as hepatic patches or metabolic activities. The functionality of hepatocytes can be enhanced and maintained for long periods in naturally fibrous structures paving way for bioartificial liver development. The phase I enzymatic activity in hepatic models can be raised exploiting the microfibrillar structure of paper to allow cellular stacking creating hypoxic conditions to induce in vivo-like xenobiotic metabolism. Lastly, the paper introduces amalgamation of carbon-based nanomaterials into existing scaffolds in liver tissue engineering. Plain Language Summary Unconventional scaffolds have the potential to meet the current challenges in liver tissue engineering- loss of hepatic morphology and functions over long-term culture, absence of native-like cell-cell and cell-matrix interactions, organization of hepatocytes into lobular structures exhibiting metabolic variations-which hinder pharmaceutical analysis, regenerative therapies and artificial organ development. Paper with cellulose microfibril network develops cellular aggregates with hypoxic conditions that influence enzymes of xenobiotic metabolism proving to be a better scaffold for hepatotoxicity testing compared with conventional monolayers in tissue culture plates. Decellularized plant stems provide already-built vasculature to be exploited for the development of intricate vessel networks that exist in hepatic lobules aiding in regenerative medicine for hepatic pathologies. Fibrous plant structures are excellent materials for the immobilization of hepatocytes and improve albumin secretion enabling their use in bioartificial liver development. Biomimicry of metabolic zonation in hepatic lobules can be achieved with perfusion culture using silk blend scaffolds with varying proportions of the liver matrix that orchestrate cellular function. The mechanical properties of silk allow the fabrication of structures that resemble liver anatomy to generate native-like hepatic lobules. Nanomaterials have immense potential as a component of composite material development for scaffolds to achieve improved predictive ability in pharmacokinetics. Most of these unconventional scaffolds have the added advantage of being readily available, accessible, affordable and sustainable for liver tissue engineering applications. Conclusively, the shift of attention away from conventional scaffolds poses a promising future in the field of tissue engineering. Graphical Abstract Article highlights Limitations of 2D culture: Current 2D culture practices cannot achieve the complexity of hepatic tissue including metabolic zonation, lobular organization, extensive vasculature, existence of multiple cell types. Splenic scaffold: Spleen proves to be the excellent choice of decellularized organ for liver tissue regeneration, however, this cross-organ recellularization procedure is not ideal for clinical translation. Plant-based scaffold: Selecting plant material that matches hepatic tissue mechanical properties and anatomical features including the channel arrangements (central vein and portal triad) help hepatic regeneration and pathological modeling. Naturally fibrous plant materials have the potential to be excellent platforms for bioartificial liver development based on high hepatocyte adherence and function. Paper-based scaffold: Hepatocyte culture on functionalized filter paper forms a physiologically more relevant model for hepatotoxicity assessment particularly because of higher activity of drug metabolizing enzymes. Silk-based scaffold: Hepatic lobular organization that supports metabolic zonation can be mimicked by varying ECM content in silk blend scaffolds to create native-like oxygen and nutrient gradient. CNT-based scaffold: Exceptional properties of carbon nanotubes make them ideal to mimic liver ECM allowing formation of hepatic spheroids with in vivo like characteristics- bile canaliculi, polarity and drug clearance. [ABSTRACT FROM AUTHOR]

The design and development of nanomaterials with intrinsic enzyme‐like activities (nanozymes) have attracted huge interest during the past several decades. Herein, by incorporating the concept of nanozyme‐involved biomimetic catalysis into the molecular assembly, we introduce an exciting example of utilizing the gold nanozyme system to expedite the sol‐gel transition of silk fibroin. In this system, silica‐encapsulated gold nanoparticles (MSN‐AuNPs) possess an intrinsic glucose oxidase‐like activity, and the activity of AuNPs has been studied by using first‐principles calculations. The catalytic oxidization of glucose into gluconic acid by MSN‐AuNPs leads to a significant decrease in the pH value of silk fibroin solution, rapidly accelerating the self‐assembly of silk fibroin solution into physical hydrogel. Since nanozymes can be further remotely controlled via different stimuli, this simple, rational control and accelerated method is a significant breakthrough, will lead to a large pool of opportunities for further exploration of nanozymes in the field of molecular assembly. [ABSTRACT FROM AUTHOR]

In this study, the electrospinning technique was employed to create a nanofiber membrane by stretching an organic polymer into nanofibers under a high electric field. Metronidazole (MNZ) at a concentration of 3 wt% was loaded into a poly(lactic-co-glycolic acid) (PLGA) and silk fibroin (SF)-blended nanofiber membrane. This formulation aims to achieve effective and sustained drug release, enabling the eradication of bacteria for the efficient treatment of periodontitis. Results demonstrated that SF interacted with PLGA molecules, forming dense and uniform nanofibers with a diameter of 570 nm. Excessive SF molecules tended to aggregate, leading to an increased particle size, with the interaction between MNZ and SF contributing to adhesion. The composition of MNZ, SF, and PLGA formed a physical chimera without any chemical reactions. Moreover, as the SF content increased, the tensile properties of the membrane gradually improved. Concurrently, the in vitro degradation rate increased with higher SF content. Among the various groups tested, the 3 wt% MNZ/PLGA/SF 2:1 membrane exhibited superior drug release characteristics, with 71.76% release within 24 h. This formulation demonstrated excellent antibacterial properties, indicated by a bacterial inhibition diameter of 13.5 mm, noteworthy hydrophilicity with a contact angle of 44.3°, and favorable biocompatibility. The membrane holds significant application value in regenerative engineering and drug delivery systems, showcasing substantial potential for the treatment of periodontitis.