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Liquid-liquid phase separation (LLPS) of proteins can be considered an intermediate solubility regime between disperse solutions and solid fibers. While LLPS has been described for several pathogenic amyloids, recent evidence suggests that it is similarly relevant for functional amyloids. Here, we review the evidence that links spider silk proteins (spidroins) and LLPS and its role in the spinning process. Major ampullate spidroins undergo LLPS mediated by stickers and spacers in their repeat regions. During spinning, the spidroins droplets shift from liquid to crystalline states. Shear force, altered ion composition, and pH changes cause micelle-like spidroin assemblies to form an increasingly ordered liquid-crystalline phase. Interactions between polyalanine regions in the repeat regions ultimately yield the characteristic β-crystalline structure of mature dragline silk fibers. Based on these findings, we hypothesize that liquid-liquid crystalline phase separation (LLCPS) can describe the molecular and macroscopic features of the phase transitions of major ampullate spidroins during spinning and speculate whether other silk types may use a similar mechanism to convert from liquid dope to solid fiber. Liquid-liquid phase separation (LLPS) of proteins can be considered an intermediate solubility regime between disperse solutions and solid fibers, relevant to both pathogenic and functional amyloids. Here, the authors review the evidence that links spider silk proteins (spidroins) and LLPS and its role in the spinning process. [ABSTRACT FROM AUTHOR]

Covalent organic frameworks designed as chromatic sensors offer opportunities to probe biological interfaces, particularly when combined with biocompatible matrices. Particularly compelling is the prospect of chemical tomography – or the 3D spatial mapping of chemical detail within the complex environment of living systems. Herein, we demonstrate a chromic Covalent Organic Framework (COF) integrated within silk fibroin (SF) microneedles that probe plant vasculature, sense the alkalization of vascular fluid as a biomarker for drought stress, and provide a 3D in-vivo mapping of chemical gradients using smartphone technology. A series of Schiff base COFs with tunable pKa ranging from 5.6 to 7.6 enable conical, optically transparent SF microneedles with COF coatings of 120 to 950 nm to probe vascular fluid and the surrounding tissues of tobacco and tomato plants. The conical design allows for 3D mapping of the chemical environment (such as pH) at standoff distances from the plant, enabling in-vivo chemical tomography. Chromatic COF sensors of this type will enable multidimensional chemical mapping of previously inaccessible and complex environments. It is promising but elusive to use covalent organic frameworks (COFs)-based chromatic sensors for chemical tomography – or the 3D spatial mapping of chemical details within living systems. Here, the authors report a COF-silk fibroin microneedle interface capable of 3D mapping of the chemical environment at standoff distances from the plant, enabling in-vivo chemical tomography. [ABSTRACT FROM AUTHOR]

Vascular covered stents play a significant therapeutic role in cardiovascular diseases. However, the poor compliance and biological inertness of commercial materials cause post-implantation complications. Silk fibroin (SF), as a biomaterial, possesses satisfactory hemocompatibility and tissue compatibility. In this study, we developed a silk film for use in covered stents by employing a layer-by-layer self-assembly strategy with regenerated SF on silk braiding fabric. We investigated the effects on the mechanical properties of the silk films in detail, which were closely correlated with fabric parameters and layer-by-layer self-assembly. The results showed that there was a significant relationship between these factors and both the compliance and mechanical strength. The 1 × 2/90°/100/SF6 film exhibited excellent mechanical properties. Notably, compliance reached 2.6%/100 mmHg, matching that of the human saphenous vein. Thus, this strategy shows promise in developing a novel covered stent, with biocompatible and comprehensive mechanical properties, and significant potential for clinical applications. [ABSTRACT FROM AUTHOR]

Nanocomposites selectively induce cancer cell death, holding potential for precise liver cancer treatment breakthroughs. This study assessed the cytotoxicity of gold nanocomposites (Au NCs) enclosed within silk fibroin (SF), aptamer (Ap), and the myogenic Talaromyces purpureogenus (TP) against a human liver cancer cell (HepG2). The ultimate product, Ap-SF-TP@Au NCs, results from a three-step process. This process involves the myogenic synthesis of TP@Au NCs derived from TP mycelial extract, encapsulation of SF on TP@Au NCs (SF-TP@Au NCs), and the conjugation of Ap within SF-TP@Au NCs. The synthesized NCs are analyzed by various characteristic techniques. Ap-SF-TP@Au NCs induced potential cell death in HepG2 cells but exhibited no cytotoxicity in non-cancerous cells (NIH3T3). The morphological changes in cells were examined through various biochemical staining methods. Thus, Ap-SF-TP@Au NCs emerge as a promising nanocomposite for treating diverse cancer cells. [ABSTRACT FROM AUTHOR]

Hydrogels can relieve wound pain and provide a moist environment for wound healing. Although hydrogels based on natural materials have proven to be biocompatible and biodegradable, their antibacterial and anti-inflammatory properties are not desirable. Natural extracts with antimicrobial and antioxidant properties are becoming increasingly attractive because of their environmentally friendly nature and good biocompatibility. Herein, composite cellulose/silk fibroin/polyacrylic acid hydrogels based on natural materials were fabricated by crosslinking between oxidized cellulose and silk fibroin together with radical polymerization of acrylic acid. The fabricated hydrogels displayed a uniform hierarchical topography with high porosity, as well as good mechanical properties, swelling properties, air permeability and biocompatibility. With the addition of tea polyphenols to natural extracts, the composite hydrogels exhibited significant antimicrobial and antioxidant properties such that they could prevent bacterial infection and relieve wound inflammation in the inflammation stage and could promote the synthesis of extracellular matrix (ECM), angiogenesis, collagenization and re-epithelization during wound healing. The tea polyphenols/cellulose/silk fibroin/polyacrylic acid hydrogels fabricated in this study can accelerate wound healing, demonstrating their great potential for application in wound dressings. [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]

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]

This study explores the modification of silk fibroin films for hydrophilic coating applications using various sugar alcohols. Films, prepared via solvent casting, incorporated glycerol, sorbitol, and maltitol, revealing distinctive transparency and UV absorption characteristics based on sugar alcohol chemical structures. X-ray diffraction confirmed a silk I to silk II transition influenced by sugar alcohols. Glycerol proved most effective in enhancing the β-sheet structure. The study also elucidated a conformational shift towards a β-sheet structure induced by sugar alcohols. Silk fibroin–sugar alcohol blind docking and sugar alcohol-sugar alcohol blind docking investigations were conducted utilizing the HDOCK Server. The computer simulation unveiled the significance of size and hydrogen bonding characteristics inherent in sugar alcohols, emphasizing their pivotal role in influencing interactions within silk fibroin matrices. Hydrophilicity of ozonized silicone surfaces improved through successful coating with silk fibroin films, particularly glycerol-containing ones, resulting in reduced contact angles. Strong adhesion between silk fibroin films and ozonized silicone surfaces was evident, indicating robust hydrogen bonding interactions. This comprehensive research provides crucial insights into sugar alcohols' potential to modify silk fibroin film crystalline structures, offering valuable guidance for optimizing their design and functionality, especially in silicone coating applications. [ABSTRACT FROM AUTHOR]

Immunoglobulin G (IgG) is an antibody used in numerous therapeutic indications. For this reason, high-purity IgG is required, which implies the use of selective adsorption chromatographic purification techniques. Although, before using chromatography, it is highly important to study the interaction between IgG and the adsorbent. Due to its characteristics, biopolymeric adsorbents are widely studied. However, there are no studies in the literature that evaluate IgG adsorption onto fibroin, a natural polymer that can be used as an ion exchange adsorbent. Thus, the aim of this work was to evaluate the adsorption of human IgG on fibroin microparticles. The microparticles were prepared from fibroin solution using the atomization method, with an average diameter of 108.5 μm. Three buffers (MOPS, MES and Tris–HCl), with different pH, were used, and for the best conditions, the influence of ionic strength (NaCl from 0 to 1 mol L−1), temperature (4 °C to 37 °C) and rotation (20 rpm to 40 rpm) were studied. The highest adsorption capacity (906.45 mg g−1) was reached with the MOPS buffer at pH 8.0, without NaCl, 25 °C and 30 rpm, which is higher than typical adsorption capacities found in the literature for other adsorbents. The adsorption capacity reduced with increasing temperature from 25 °C to 37 °C and rotation rate from 30 to 40 rpm. The thermodynamic parameters demonstrated that adsorption is spontaneous and endothermic. These results open up new possibilities of application of fibroin microparticles, considering the medium in which they are inserted, and highlights the improvement of IgG chromatographic purification for uses in pharmaceutical field. [ABSTRACT FROM AUTHOR]

Targeted drug delivery has a positive impact on the concentration of anticancer drugs at the tumor site and can reduce harmful side effects. In this research, silk fibroin and sodium alginate were utilized to produce nanoparticles, which were then targeted using sodium alendronate (SF-SA-ALN NPs) to improve the effectiveness of chemotherapy on osteosarcoma. The resulting nanoparticles had a surface charge of -50.5 mV and an average size of 252 nm (with PDI = 0.157). Doxorubicin (DOX) was loaded onto the nanoparticles using ionic interaction with 96% drug loading efficiency. The nanoparticles showed higher drug release at pH 5.4 compared to pH 7.4. It was also investigated the effectiveness of in vitro bone targeting using hydroxyapatite (HA) as a bone model, and found that targeted nanoparticles accumulated in HA crystals. The toxicity of the drug-loaded nanoparticles on a human osteosarcoma cell line (MG-63) revealed that the drug-targeted nanoparticles were more toxic than free drug after 24 h. This may be due to the presence of alendronate on the SF-SA-ALN NPs, which allowed for internalization of the nanoparticles through endocytosis. Overall, these nanoparticles show promise as a potential drug delivery system for osteosarcoma treatment. [ABSTRACT FROM AUTHOR]

In the field of biomedical engineering, nanofiber scaffolds have excellent biomaterial properties, making them highly suitable for superior wound dressing applications. This work presents the fabrication of a novel bimetal blend comprising palladium and platinum nanoparticles integrated with silk fibroin and collagen composite nanofibers through the electrospinning method. The fabricated composite nanofibrous scaffolds were investigated to analyze their chemical composition, surface morphology, thermal stability, porosity, hemocompatibility, mechanical strength, swelling, and degradation properties. The average diameter length of the SF/CL/Pd–Pt composite nanofiber scaffolds is 141.62 ± 33.03 nm, with Pd and Pt nanoparticle diameters measured at 8.64 and 7.36 nm, respectively. In vitro assessments of SF/CL and SF/CL/Pd–Pt composite nanofiber scaffolds demonstrated outstanding antibacterial efficacy against both gram-positive (S. aureus) and gram-negative (E. coli) bacteria. The antioxidant activity of SF/CL/Pd–Pt composite nanofibers exhibited a free radical scavenging percentage of 94.34%. Additionally, cell proliferation studies conducted on the fibroblast (NIH3T3) cell line, along with in vivo investigations on male Sprague–Dawley rats, underscored the remarkable wound-healing ability of the SF/CL/Pd–Pt composite nanofiber scaffolds. Furthermore, histopathological examination of wounded tissue samples using H&E and Masson trichrome staining revealed faster reepithelialization, granulation, angiogenesis, and reduced inflammatory response. These findings demonstrate that SF/CL/Pd–Pt composite nanofibrous scaffolds are excellent wound dressing materials for all biomedical applications. [ABSTRACT FROM AUTHOR]

The major ampullate Spidroin 1 (MaSp1) is the main protein of the dragline spider silk. The C-terminal (CT) domain of MaSp1 is crucial for the self-assembly into fibers but the details of how it contributes to the fiber formation remain unsolved. Here we exploit the fact that the CT domain can form silk-like fibers by itself to gain knowledge about this transition. Structural investigations of fibers from recombinantly produced CT domain from E. australis MaSp1 reveal an α-helix to β-sheet transition upon fiber formation and highlight the helix No4 segment as most likely to initiate the structural conversion. This prediction is corroborated by the finding that a peptide corresponding to helix No4 has the ability of pH-induced conversion into β-sheets and self-assembly into nanofibrils. Our results provide structural information about the CT domain in fiber form and clues about its role in triggering the structural conversion of spidroins during fiber assembly. The mechanical properties of spider silk are a consequence of the structural organisation of proteins known as spidroins. Here the authors investigate the structure of the fibers formed by a C-terminal domain of a major spidroin: the study elucidates the mechanisms by which spidroins are transformed from soluble form into a fiber. [ABSTRACT FROM AUTHOR]

Silk nanofibrils (SNFs), the fundamental building blocks of silk fibers, endow them with exceptional properties. However, the intricate mechanism governing SNF assembly, a process involving both protein conformational transitions and protein molecule conjunctions, remains elusive. This lack of understanding has hindered the development of artificial silk spinning techniques. In this study, we address this challenge by employing a graphene plasmonic infrared sensor in conjunction with multi-scale molecular dynamics (MD). This unique approach allows us to probe the secondary structure of nanoscale assembly intermediates (0.8–6.2 nm) and their morphological evolution. It also provides insights into the dynamics of silk fibroin (SF) over extended molecular timeframes. Our novel findings reveal that amorphous SFs undergo a conformational transition towards β-sheet-rich oligomers on graphene. These oligomers then connect to evolve into SNFs. These insights provide a comprehensive picture of SNF assembly, paving the way for advancements in biomimetic silk spinning. Here, the authors develop a graphene plasmonic infrared sensor to probe the secondary structure of nanoscale assembly intermediates and the morphological evolution of silk nanofibrils, the fundamental building blocks of silk fibres. [ABSTRACT FROM AUTHOR]

Millirobots must have low cost, efficient locomotion, and the ability to track target trajectories precisely if they are to be widely deployed. With current materials and fabrication methods, achieving all of these features in one millirobot remains difficult. We develop a series of graphene-based helical millirobots by introducing asymmetric light pattern distortion to a laser-induced polymer-to-graphene conversion process; this distortion resulted in the spontaneous twisting and peeling off of graphene sheets from the polymer substrate. The lightweight nature of graphene in combine with the laser-induced porous microstructure provides a millirobot scaffold with a low density and high surface hydrophobicity. Magnetically driven nickel-coated graphene-based helical millirobots with rapid locomotion, excellent trajectory tracking, and precise drug delivery ability were fabricated from the scaffold. Importantly, such high-performance millirobots are fabricated at a speed of 77 scaffolds per second, demonstrating their potential in high-throughput and large-scale production. By using drug delivery for gastric cancer treatment as an example, we demonstrate the advantages of the graphene-based helical millirobots in terms of their long-distance locomotion and drug transport in a physiological environment. This study demonstrates the potential of the graphene-based helical millirobots to meet performance, versatility, scalability, and cost-effectiveness requirements simultaneously. Millirobots effective application generally depends on cost, scalability, efficient locomotion, and the ability to track target trajectory precisely. Here, authors demonstrate promising graphene-based helical millirobots by introducing asymmetric light pattern distortion to a laser-induced graphene process. [ABSTRACT FROM AUTHOR]

The regeneration of critical-size bone defects, especially those with irregular shapes, remains a clinical challenge. Various biomaterials have been developed to enhance bone regeneration, but the limitations on the shape-adaptive capacity, the complexity of clinical operation, and the unsatisfied osteogenic bioactivity have greatly restricted their clinical application. In this work, we construct a mechanically robust, tailorable and water-responsive shape-memory silk fibroin/magnesium (SF/MgO) composite scaffold, which is able to quickly match irregular defects by simple trimming, thus leading to good interface integration. We demonstrate that the SF/MgO scaffold exhibits excellent mechanical stability and structure retention during the degradative process with the potential for supporting ability in defective areas. This scaffold further promotes the proliferation, adhesion and migration of osteoblasts and the osteogenic differentiation of bone marrow mesenchymal stem cells (BMSCs) in vitro. With suitable MgO content, the scaffold exhibits good histocompatibility, low foreign-body reactions (FBRs), significant ectopic mineralisation and angiogenesis. Skull defect experiments on male rats demonstrate that the cell-free SF/MgO scaffold markedly enhances bone regeneration of cranial defects. Taken together, the mechanically robust, personalised and bioactive scaffold with water-responsive shape-memory may be a promising biomaterial for clinical-size and irregular bone defect regeneration. The regeneration of critical-size bone defects, especially those with irregular shapes, remains a clinical challenge. Here, the authors report a shape-memory, tailorable, self-adaptive and bioactive silk fibroin/magnesium composite scaffold that can quickly match irregular defects by simple trimming and lead to good interface integration. [ABSTRACT FROM AUTHOR]

Effective mineralization of biological structures poses a significant challenge in hard tissue engineering as it necessitates overcoming geometric complexities and multistep biomineralization processes. In this regard, we propose "mineral-in-shell nanoarchitectonics", inspired by the nanostructure of matrix vesicles, which can influence multiple mineralization pathways. Our nanostructural design empowers mineral precursors with tailorable properties through encapsulating amorphous calcium phosphate within a multifunctional tannic acid (TA) and silk fibroin (SF) nanoshell. The bioinspired nanosystem facilitates efficient recruitment of mineral precursors throughout the dentin structures, followed by large-scale intradentinal mineralization both in vitro and in vivo, which provides persistent protection against external stimuli. Theoretical simulations combined with experimental studies attribute the success of intradentinal mineralization to the TA-SF nanoshell, which exhibits a strong affinity for the dentin structure, stabilizing amorphous precursors and thereby facilitating concomitant mineral formation. Overall, this bioinspired mineral-in-shell nanoarchitectonics shows a promising prospect for hard tissue repair and serves as a blueprint for next-generation biomineralization-associated materials. [ABSTRACT FROM AUTHOR]

Silk fibroin (SF) has been utilized in various applications, including as, in bone, cartilage, nerve, skin regeneration, owing to its biocompatibility, controllable biodegradability, minimal inflammation, and tunable mechanical properties. Excellent neovascularization of silk matrices is prerequisite for the success of promoting wound healing in different tissues. Neovascularization of SF can provide a nutrient supply to the newly developed granulation tissue at the wound site and accelerate vessel formation and remodeling. In this review, we summarize the neovascularization of SF in different forms and dissolution by recombining different composites, modifying active peptides, and adding growth factors in the treatment of various wound healing processes. [ABSTRACT FROM AUTHOR]

Solar vapor generation is a promising sustainable technology that uses solar distillation to produce fresh water from seawater and wastewater, helping relieve global water resource shortage. Here, inspired by naturally grown integrally molded mulberry leaves with a Janus hydrophilic and hydrophobic structure, a novel, simple, and efficient integrated molding method is proposed to break through the limitations of the traditional split manufacturing strategy and realizes the integrated formation of Janus evaporator. Based on the spontaneous sedimentation characteristics of MXene in silk fibroin solution and its regulation of mesoscopic structure and hydrophilicity of silk fibroin, layered structures with different compositions and hydrophilicities were obtained in one step. Meanwhile, ethanol and glutaraldehyde were added to construct a physical crystallization-chemical crosslinking dual stabilization structure in silk fibroin. Our evaporator has the evaporation rate of 3.07 kg·m−2·h−1 and the efficiency of 86.8% under 1 sun and maintains high evaporation performance under various extreme test conditions including vigorous washing, repeated compression, and high-intensity ultraviolet (UV) irradiation. Additionally, the evaporator performs well in practical application scenarios, its evaporation rate in the simulated Dead Sea seawater exceeds 2.13 kg·m−2·h−1, and more than 99.9% of the salt, heavy metal ions, oil pollution, and dyes are purified. [ABSTRACT FROM AUTHOR]

It remains a significant challenge to fabricate natural polymer (NP) hydrogels with anti-swelling ability and high strengths in the physiological environment. Herein, the β-sheet-reinforced NP hydrogel is developed by copolymerizing methacrylated gelatin (GelMA) and methacrylated silk fibroin (SFMA) in aqueous solution, followed by ethanol treatment (named GelMA-SFMA-AL). The β-sheets formed by SFMA can act as a stable physical crosslink to enhance the mechanical properties and prolong the degradation of the GelMA network. Importantly, the chemical crosslinking in the GelMA-SFMA hydrogel prevents excessive aggregation of hydrophobic β-sheets, thereby avoiding the formation of brittle hydrogel. The obtained GelMA-SFMA-AL hydrogels exhibit considerably enhanced mechanical properties (Young's modulus: 0.89–3.68 MPa; tensile strength: 0.31–0.96 MPa; toughness: 0.09–0.63 MJ/m3; compressive modulus: 0.78–2.20 MPa; compressive strength: 2.65–5.93 MPa) compared with GelMA-SFMA hydrogels (Young's modulus: 0.04–0.13 MPa; tensile strength: 0.04–0.07 MPa; toughness: 0.01–0.02 MJ/m3; compressive modulus: 0.03–0.09 MPa; compressive strength: 0.30–0.64 MPa). A bilayer osteochondral scaffold is constructed via digital light processing (DLP) three-dimensiaonl (3D) printing technology, comprising GelMA-SFMA@diclofenac sodium (DS)-AL as the top layer and GelMA-SFMA@bioactive glass (BG)-AL as the bottom layer. The bilayer hydrogel scaffold is demonstrated to support cell attachment and spreading, and facilitate osteogenic differentiation of rat bone marrow stem cells in vitro. In vivo implantation experiment suggests this bilayer scaffold is promising to be used for osteo-chondral tissue regeneration. [ABSTRACT FROM AUTHOR]

Despite orientationally variant tears of the meniscus, suture repair is the current clinical gold treatment. However, inaccessible tears in company with re-tears susceptibility remain unresolved. To extend meniscal repair tools from the perspective of adhesion and regeneration, we design a dual functional biologic-released bioadhesive (S-PIL10) comprised of methacrylated silk fibroin crosslinked with phenylboronic acid-ionic liquid loading with growth factor TGF-β1, which integrates chemo-mechanical restoration with inner meniscal regeneration. Supramolecular interactions of β-sheets and hydrogen bonds richened by phenylboronic acid-ionic liquid (PIL) result in enhanced wet adhesion, swelling resistance, and anti-fatigue capabilities, compared to neat silk fibroin gel. Besides, elimination of reactive oxygen species (ROS) by S-PIL10 further fortifies localized meniscus tear repair by affecting inflammatory microenvironment with dynamic borate ester bonds, and S-PIL10 continuously releases TGF-β1 for cell recruitment and bridging of defect edge. In vivo rabbit models functionally evidence the seamless and dense reconstruction of torn meniscus, verifying that the concept of meniscus adhesive is feasible and providing a promising revolutionary strategy for preclinical research to repair meniscus tears. Suture repair is the current clinical treatment for meniscus tears, but inaccessible tears in company with re-tears susceptibility remain unresolved. Here the authors address these issues by developing a meniscus adhesive-based strategy for the seamless and dense reconstruction of torn meniscus. [ABSTRACT FROM AUTHOR]

Degradable wearable electronics are attracting increasing attention to weaken or eliminate the negative effect of waste e-wastes and promote the development of medical implants without secondary post-treatment. Although various degradable materials have been explored for wearable electronics, the development of degradable wearable electronics with integrated characteristics of highly sensing performances and low-cost manufacture remains challenging. Herein, we developed a facile, low-cost, and environmentally friendly approach to fabricate a biocompatible and degradable silk fibroin based wearable electronics (SFWE) for on-body monitoring. A combination of rose petal templating and hollow carbon nanospheres endows as-fabricated SFWE with good sensitivity (5.63 kPa−1), a fast response time (147 ms), and stable durability (15,000 cycles). The degradable phenomenon has been observed in the solution of 1 M NaOH, confirming that silk fibroin based wearable electronics possess degradable property. Furthermore, the as-fabricated SFWE have been demonstrated that have abilities to monitor knuckle bending, muscle movement, and facial expression. This work offers an ecologically-benign and cost-effective approach to fabricate high-performance wearable electronics. [ABSTRACT FROM AUTHOR]

The repair of cartilage injuries and defects in the knee presents a significant challenge in the field of human joint surgery. A promising solution involves the synergy of three-dimensional printing and articular cartilage tissue engineering. This research primarily focuses on the formulation of composite hydrogels comprising gelatin methacryloyl (GelMA), silk fibroin (SF) and hydroxyapatites (Haps), with a thorough examination of their morphology and mechanical properties. We also conducted tests on stacking height and grid area to assess the 3D printability of GM/SF/Haps inks. To evaluate the suitability of GM/SF/Haps scaffolds in cartilage regeneration, we performed 2D culture with mouse chondrocytes (ATDC5) inoculated on hydrogel surface and 3D culture with ATDC5 mixed in printing scaffolds. The assessment involved various techniques, such as Live/Dead staining, Cell Counting Kit-8 (CCK-8) assay, immunofluorescence staining and cytoskeleton staining. The outcomes of this investigation revealed that the inclusion of Haps significantly enhanced cell viability, cell proliferation and the differentiation of chondrocytes within the composite scaffolds. Consequently, this study underscores the promising potential of GM/SF/Haps scaffolds in the domain of cartilage regeneration. [ABSTRACT FROM AUTHOR]

Critical-sized bone defects, commonly encountered in clinical orthopedic surgery, present a significant challenge. One of the promising solutions is to prepare synthetic bone substitute materials with precise structural control, mechanical compatibility, and enhanced osteogenic induction performance, nevertheless the successful preparation of such materials remains difficult. In this study, a two-step technique, integrating an extrusion-based printing process with biomimetic mineralization induced by alkaline phosphatase (ALP), was developed. Initially, a pre-cured hydrogel of regenerated silk fibroin (RSF) with a small quantity of hydroxypropyl cellulose (HPC) and ALP was prepared through heating the mixed aqueous solution. This pre-cured hydrogel demonstrated thixotropic property and could be directly extruded into predetermined structures through a 3D-printer. Subsequently, the 3D-printed RSF-based materials with ALP underwent biomimetic in situ mineralization in calcium glycerophosphate (Ca-GP) mineralizing solution, utilizing the polymer chains of RSF as templates and ALP as a trigger for cleaving phosphate bonds of Ca-GP. The resulting 3D-printed RSF-mineral composites including hydrogel and sponge possessed adjustable compression modulus of megapascal grade and variable hydroxyapatite content, which could be controlled by manipulating the duration of the mineralization process. Moreover, these 3D-printed RSF-mineral composites demonstrated non-cytotoxicity towards rat bone marrow mesenchymal stem cells. Therefore, they may hold great potential for applications involving the replacement of tissues characterized by osteoinductivity and intricate structures. [ABSTRACT FROM AUTHOR]

In recent years, hydrogels had a wide range of applications in wearable devices, human health monitoring, or implantable sensors because of their good properties such as stretchability, conductivity, frost resistance, and transparency. However, the simultaneous integration of excellent mechanical properties and high electrical conductivity in a hydrogel sample still needs to be improved. In this work, silk fibroin (SF) and poly(3,4-ethylene dioxythiophene):poly(styrene sulfonate) (PEDOT:PSS) were introduced into a poly(vinyl alcohol)/poly(acrylic amide) (PVA/PAM) double-network hydrogel to prepare PVA/PAM/SF/PEDOT:PSS hydrogel electrolytes via a one-pot method. Adding SF also enhances the mechanical properties of the hydrogel, making it three times stronger than the PVA/PAM double-network hydrogel. The hydrogel is versatile, with a strain range of 1–300%, making it an ideal resistive sensor for monitoring body pressure. More importantly, due to the hydrogel's adhesion strength of approximately 665.8 kPa, the hydrogel can adhere to other surfaces during the detection process, significantly reducing the signal loss due to insufficient adhesion. In addition, the hydrogel also exhibits excellent electrical conductivity, can sensitively detect human limb movement, and can be applied to flexible electronic products such as electronic skin and soft robots. [ABSTRACT FROM AUTHOR]

Controlled release of proteins, such as growth factors, from biocompatible silk fibroin (SF) hydrogel is valuable for its use in tissue engineering, drug delivery, and other biological systems. To achieve this, we introduced silk fibroin-mimetic peptides (SFMPs) with the repeating unit (GAGAGS)n. Using green fluorescent protein (GFP) as a model protein, our results showed that SFMPs did not affect the GFP function when conjugated to it. The SFMP-GFP conjugates incorporated into SF hydrogel did not change the gelation time and allowed for controlled release of the GFP. By varying the length of SFMPs, we were able to modulate the release rate, with longer SFMPs resulting in a slower release, both in water at room temperature and PBS at 37 °C. Furthermore, the SF hydrogel with the SFMPs showed greater strength and stiffness. The increased β-sheet fraction of the SF hydrogel, as revealed by FTIR analysis, explained the gel properties and protein release behavior. Our results suggest that the SFMPs effectively control protein release from SF hydrogel, with the potential to enhance its mechanical stability. The ability to modulate release rates by varying the SFMP length will benefit personalized and controlled protein delivery in various systems. [ABSTRACT FROM AUTHOR]

For the synthesis of zinc oxide nanoparticles, a bioactive, cost-effective, and sustainable material such as the chitosan/silk fibroin blend was developed. The current research was aimed to elucidate the antibacterial activity of silk fibroin–chitosan blend ZnO NPs at various pH (4, 8 and 12) and temperatures (4, 37, and 50 °C) against gram-negative (Klebsiella pneumoniae, Escherichia coli, Serratia rubidaea, and Proteus mirabilis) and gram-positive bacterial strains (Staphylococcus aureus, Bacillus thuringensis, Bacillus licheniformis, and Clostridium difficile) at numerous concentrations (2–8 mg/ml). Agar well diffusion method was used to evaluate the antibacterial effect by measuring the zone of inhibition. Silk fibroin–chitosan blend ZnO NPs significantly reserved the growth of gram-negative bacterial strains, e.g., K. pneumoniae (11.3 ± 0.9 mm), E. coli (12.7 ± 0.9 mm), S. rubidaea (16.7 ± 0.9 mm), and P. mirabilis (11.7 ± 1.2 mm) and gram-positive bacterial strains such as B. thuringiensis (12.3 ± 0.3 mm), B. licheniformis (10.0 ± 0.57 mm), S. aureus (17.3 ± 1.2 mm), and C. difficile (11.7 ± 1.2 mm). At various temperatures and various pH values (acidic and basic), the stability of silk fibroin–chitosan blend ZnO NPs was observed. Silk fibroin–chitosan blend ZnO NPs significantly inhibited the growth of all bacterial strains at 37°C, and a maximum zone of inhibition was found at pH 8. The formation of SFCH blend ZnONPs was confirmed via numerous characterization techniques such as ultraviolet visible spectrum, Fourier transform infrared spectroscopy (FTIR), X-ray diffraction, and transmission electron microscopy (TEM). Transmission electron microscopy revealed that SFCH blend ZnONPs were highly stabilized and homogeneously distributed in the solution, and the average particle size was about 30.06 nm with a spherical shape. We concluded that silk fibroin–chitosan zinc oxide nanocomposite could be a safe and promising antimicrobial agent for wound dressing and various applications in biomaterials. [ABSTRACT FROM AUTHOR]

Electrospun scaffolds play important roles in the fields of regenerative medicine and vascular tissue engineering. The aim of the research described here was to develop a vascular scaffold that mimics the structural and functional properties of natural vascular scaffolding. The mechanical properties of artificial vascular tissue represent a key issue for successful transplantation in small diameter engineering blood vessels. We blended silk fibroin (SF) and fibrin to fabricate a composite scaffold using electrospinning to overcome the shortcomings of fibrin with respect to its mechanical properties. Subsequently, we then carefully investigated the morphological, mechanical properties, hydrophilicity, hemocompatibility, degradation, cytocompatibility and biocompatibility of the SF/fibrin (0:100), SF/fibrin (15:85), SF/fibrin (25:75), and SF/fibrin (35:65) scaffolds. Based on these in vitro results, we implanted SF/fibrin (25:75) vascular scaffold subcutaneously and analyzed its in vivo degradation and histocompatibility. The fiber structure of the SF/fibrin hybrid scaffold was smooth and uniform, and its fiber diameters were relatively small. Compared with the fibrin scaffold, the SF/fibrin scaffold clearly displayed increased mechanical strength, but the hydrophilicity weakened correspondingly. All of the SF/fibrin scaffolds showed excellent blood compatibility and appropriate biodegradation rates. The SF/fibrin (25:75) scaffold increased the proliferation and adhesion of MSCs. The results of animal experiments confirmed that the degradation of the SF/fibrin (25:75) scaffold was faster than that of the SF scaffold and effectively promoted tissue regeneration and cell infiltration. All in all, the SF/fibrin (25:75) electrospun scaffold displayed balanced and controllable biomechanical properties, degradability, and good cell compatibility. Thus, this scaffold proved to be an ideal candidate material for artificial blood vessels. [ABSTRACT FROM AUTHOR]

Due to the unique properties of the silk fibroin (SF) made from silkworm, SF-based hydrogels have recently received significant attention for various biomedical applications. However, research on the SF-based hydrogels isolated from spider silks has been rtricted due to the limited collection and preparation of naïve silk materials. Therefore, this study focused on the microstructural characteristics of hydrogel scaffolds derived from two types of woven silk glands: the major ampullate gland (MAG) and the tubuliform gland (TG), in the orb-web spider Trichonephila clavate. We compared these spider glands with those of the silk fibroin (SF) hydrogel scaffold extracted from the cocoon of the insect silkworm Bombyx mori. Our FESEM analysis revealed that the SF hydrogel has high porosity, translucency, and a loose upper structure, with attached SF fibers providing stability. The MAG hydrogel displayed even higher porosity, as well as elongated fibrous structures, and improved mechanical properties: while the TG hydrogel showed increased porosity, ridge-like or wall-like structures, and stable biocapacity formed by physical crosslinking. Due to their powerful and versatile microstructural characteristics, the MAG and TG hydrogels can become tailored substrates, very effective for tissue engineering and regenerative medicine applications. [ABSTRACT FROM AUTHOR]

Spider silks are well known for their exceptional mechanical properties that are tougher than Kevlar and steel. However, the restricted production amounts from their native sources limit applications of spider silks. Over the decades, there have been significant interests in fabricating man-made silk fibers with comparable performance to natural silks, inspiring many efforts both for biosynthesizing recombinant spider silk proteins (spidroins) in amenable heterologous hosts and biomimetic spinning of artificial spider silks. These strategies provide promising routes to produce high-performance and functionally optimized fibers with diverse applications. Herein, we summarize the hosts that have been applied to produce recombinant spidroins. In addition, the fabrication and mechanical properties of recombinant spidroin fibers and their composite fibers are also introduced. Furthermore, we demonstrate the applications of recombinant spidroin-based fibers. Finally, facing the challenges in biosynthesis, scalable production, and hierarchical assembly of high-performance recombinant spidroins, we give a summary and perspective on future development. [ABSTRACT FROM AUTHOR]

Background: Cocoonase is a proteolytic enzyme released by silk moths during pupal adult emergence. Without damaging the silk fibroin, this enzyme dissolves the shell of the tasar cocoon by exclusively targeting the protein sericin. Prior to this study, there was no available antibody against Antheraea mylitta cocoonase to identify or screen out similar variants or cocoonase like protein. Results: In the present study, naturally secreted A. mylitta cocoonase was purified and used to immunize New Zealand white rabbits. The developed polyclonal antibody of cocoonase was purified and its specific interaction with cocoonase was determined using Indirect ELISA. The confirmation of its specificity and immuno-reactivity was evaluated by western blot using native cocoonase of tasar silkworm A. mylitta. The efficacy and specificity of the polyclonal antibody were further verified and confirmed by western blot which was performed to detect ten different ecotypes of A. mylitta cocoonase. Conclusion: The developed antibody successfully detected the cocoonase of different ecotypes. Thus, in future this antibody can serve as one of the molecular detection method for cocoonase and cocoonase-like proteins. [ABSTRACT FROM AUTHOR]

Colchicine is the first-line option for both the treatment and prophylaxis of gout flares. However, due to potentially severe side effects, the clinical use of colchicine is limited. A well-tolerated and safe delivery system for colchicine is widely desired. For this purpose, colchicine-loaded inseparable microneedles were fabricated using silk fibroin. Additionally, separable microneedles made of silk fibroin as the needle tips and PVP K30 as the base material were developed. Both types of microneedles were evaluated for their mechanical strength, swelling and dissolution characteristics, insertion abilities, degradation properties, in vitro penetration, skin irritation, and in vivo anti-gout effects. The results demonstrated that separable microneedles had greater mechanical strength and insertion ability. Moreover, the separable microneedles separated quickly and caused little skin irritation. In the pharmacodynamic test, mice with acute gouty arthritis responded significantly to treatment with separable microneedles. In conclusion, the separable silk fibroin-based microneedles provide a promising route for colchicine delivery. [ABSTRACT FROM AUTHOR]

Silk fibroin is a widely used biocompatible medical material with tunable mechanical, degradability and environmental non-toxicity. This paper prepared the silk fibroin/chitosan hydrogel microneedle with pH sensitivity by blending silk fibroin with chitosan to induce graft cross-linking. The cross-linked silk fibroin/chitosan microneedles network is expanded by hydrogen ions and water molecules, forming a more significant swelling. In vitro, the transdermal drug release showed that insulin loaded in microneedles exhibited pH-sensitive drug release behavior and was released faster under acidic conditions than under neutral conditions. By changing the pH of the solution, microneedles can achieve a stimulating response to the environment, thereby intelligently regulating the transdermal release of insulin. [ABSTRACT FROM AUTHOR]

Silk fibroin is a natural, protein-based biopolymer produced by silkworm and obtained from silkworm cocoons. It has such features as biocompatibility, biodegradability, high mechanical resistance, low immunogenicity and low inflammatory response. Owing to these properties, it attracts attention in various fields including tissue engineering and drug delivery. The silk fibroin production method basically consists of processes such as degumming, extraction, dialysis, centrifugation, and, if necessary, lyophilization. Since the production of silk fibroin from cocoons includes many steps, there are various parameters that affect the protein content of silk fibroin. In this study, it was aimed to validate the production process steps which mainly affect the silk fibroin content and to determine optimum parameters to obtain silk fibroin with higher protein content. For this purpose, the effects of the type of extraction agent (Ajisawa's reagent or lithium bromide), the molecular weight cutoff value (MWCO) of the dialysis membrane, the dialysis time, and the centrifugation process were evaluated statistically with one-way analysis of variance method. According to the results, the highest protein content is obtained using, LiBr as extraction agent, 3500 Da as MWCO value of dialysis membrane, 2 days as dialysis time and 532 RCF for 5 min as conditions of centrifugation process. [ABSTRACT FROM AUTHOR]

Purpose: Post-interventional hemorrhage can result in serious complications, especially in patients with hemostatic disorders. Identification of safe and efficient local hemostatic agents is important, particularly in the context of an ageing society and the emergence of new oral anticoagulants. The aim of this in vitro study was to investigate the potential of silk fibroin membranes coated with the inorganic polymer polyphosphate (polyP) as a novel hemostatic device in oral surgery. Methods: Cocoons of the silkworm Bombyx mori were degummed and dissolved. Varying amounts of long-chain polyP (2–2000 µg/mm2) were adsorbed to the surface of silk fibroin membranes. Analysis of the procoagulant effect of polyP-coated silk membranes was performed using real-time thrombin generation assays in human plasma. Increasing concentrations of polyP (0.15–500 µg/ml) served as a positive control, while uncoated silk fibroin membranes were used as negative control. Results: PolyP-coated silk fibroin membranes triggered coagulation when compared to plasma samples and pure silk fibroin membranes. A polyP-dose-dependent effect of thrombin generation could be found with a maximum (ETP = 1525.7 nM⋅min, peak thrombin = 310.1 nM, time to peak = 9.8 min, lag time = 7.6 min.) at 200 µg/mm2 of polymer loading on the silk fibroin membrane surface. Conclusions: In this study, it was demonstrated that silk fibroin membranes coated with polyP have the potential to act as a promising novel hemostatic device. [ABSTRACT FROM AUTHOR]

Silk fibroin (SF) is a natural polymer with excellent biocompatibility and mechanical properties and moderate human body degradability, making SF an interesting candidate for regenerative medicine. Composite materials of SF and polyethylene glycidyl methacrylate (PEGDMA), a biocompatible polymer, attract attention as scaffold materials for regenerative medicine. To the authors' knowledge, SF–PEGDMA composite hydrogels have thus far not been manufactured using optical fabrication methods, and the change in their compressive properties during their degradation has not been studied. In addition, cellulose nanofiber (CNF), a plant-derived nanomaterial with excellent mechanical properties and biocompatibility, was added to the SF–PEGDMA hydrogels to enhance their mechanical properties. SF–PEGDMA composite hydrogels were three-dimensionally printed using digital light processing. The compressive strength of the obtained hydrogels stored in pure water or phosphate buffer solution temporarily increased and decreased after 4 days. However, after 7 days, the strength decreased to a level similar to that of the specimens which did not contain CNF. In the formability tests, the reproducibility of the model changed with the intensity of the light and the CNF concentration. [ABSTRACT FROM AUTHOR]

A stable and recyclable of BiOBr/silk fibroin-cellulose acetate composite film was prepared by blending-wet phase transformation and in situ precipitate technology. The cellulose acetate film modified by silk fibroin formed a finger-shaped porous structure, which provided a large space for the uniform growth of BiOBr nanosheets and facilitated the shuttle flow of dyes in film. The morphology, phase structure, and optical properties of the composite films were characterized using various techniques, and their photocatalytic performance for dye wastewater was evaluated under visible light irradiation. Results showed that the BiOBr/SF-CA composite film exhibited efficient photocatalytic activity with 99.9% of rhodamine B degradation rate. Moreover, the composite film maintained high catalytic stability because Bi as the active species deposited on the film showed almost no loss. Finally, the possible photocatalytic mechanisms in the BiOBr/SF-CA composite film were speculated through radical-trapping experiments and electron spin resonance testing. [ABSTRACT FROM AUTHOR]

As an FDA-approved biopolymer, silk has been contemplated for a wide range of applications based on its unique merits, such as biocompatibility, biodegradability, and piezoelectricity. As silk, in both crystalline structure and amorphous state, exhibits unique physical, mechanical, and biological properties (promoting cell migration, differentiation, growth, and protein-surface interaction), it is fruitful to understand its potential applications. Sensors, actuators, and drug delivery systems are the best in case. As such, the current effort first introduces silk fibroin (SF) and delineates its characteristics. It then explores the extensive use of this biomaterial in tissue engineering approaches, in addition to its biosensor and electro-active wearable bioelectronic application. To this end, the SF application in cardiovascular, skin, cartilage, and drug delivery systems for cancer therapy and wound healing was studied precisely. Compositing any type of other variables to induce a specific application or improve any SF barriers, namely its hydrophobicity, poor electrical conductivity, or tuning its mechanical properties, especially in tissue engineering applications, has also been discussed wherever it is deemed informative. [ABSTRACT FROM AUTHOR]

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Prolonged inflammation can impede wound healing, which is regulated by several proteins and cytokines, including IL-4, IL-10, IL-13, and TGF-β. Concentration-dependent effects of these molecules at the target site have been investigated by researchers to develop them as wound-healing agents by regulating signaling strength. Nanotechnology has provided a promising approach to achieve tissue-targeted delivery and increased effective concentration by developing protein-functionalized nanoparticles with growth factors (EGF, IGF, FGF, PDGF, TGF-β, TNF-α, and VEGF), antidiabetic wound-healing agents (insulin), and extracellular proteins (keratin, heparin, and silk fibroin). These molecules play critical roles in promoting cell proliferation, migration, ECM production, angiogenesis, and inflammation regulation. Therefore, protein-functionalized nanoparticles have emerged as a potential strategy for improving wound healing in delayed or impaired healing cases. This review summarizes the preparation and applications of these nanoparticles for normal or diabetic wound healing and highlights their potential to enhance wound healing. [ABSTRACT FROM AUTHOR]

Highlights: A humanoid intelligent display platform (HIDP) is created using stretchable and resilient ionotronic materials, and can be applicable in extreme environments and complex mechanical stimulations. HIDP links sound amplitude and brightness through machine learning for audiovisual interaction. HIDP identifies and displays animal species and corresponding frequencies in real-time. This study proposes a rational strategy for the design, fabrication and system integration of the humanoid intelligent display platform (HIDP) to meet the requirements of highly humanized mechanical properties and intelligence for human–machine interfaces. The platform's sandwich structure comprises a middle light-emitting layer and surface electrodes, which consists of silicon elastomer embedded with phosphor and silk fibroin ionoelastomer, respectively. Both materials are highly stretchable and resilient, endowing the HIDP with skin-like mechanical properties and applicability in various extreme environments and complex mechanical stimulations. Furthermore, by establishing the numerical correlation between the amplitude change of animal sounds and the brightness variation, the HIDP realizes audiovisual interaction and successful identification of animal species with the aid of Internet of Things (IoT) and machine learning techniques. The accuracy of species identification reaches about 100% for 200 rounds of random testing. Additionally, the HIDP can recognize animal species and their corresponding frequencies by analyzing sound characteristics, displaying real-time results with an accuracy of approximately 99% and 93%, respectively. In sum, this study offers a rational route to designing intelligent display devices for audiovisual interaction, which can expedite the application of smart display devices in human–machine interaction, soft robotics, wearable sound-vision system and medical devices for hearing-impaired patients. [ABSTRACT FROM AUTHOR]

The present work had evaluated the effect of cryogenic treatment (233 K) on the degradation of polymeric biomaterial using a numerical model. The study on effect of cryogenic temperature on mechanical properties of cell-seeded biomaterials is very limited. However, no study had reported material degradation evaluation. Different structures of silk-fibroin-poly-electrolyte complex (SFPEC) scaffolds had been designed by varying hole distance and hole diameter, with reference to existing literature. The size of scaffolds were maintained at 5 × 5 mm2. Current study evaluates the effect of cryogenic temperature on mechanical properties (corelated to degradation) of scaffold. Six parameters related to scaffold degradation: heat transfer, deformation gradient, stress, strain, strain tensor, and displacement gradient were analyzed for three different cooling rates (− 5 K/min, − 2 K/min, and − 1 K/min). Scaffold degradation had been evaluated in the presence of water and four different concentrations of cryoprotectant solution. Heat distribution at various points (points_base, point_wall and point_core) on the region of interest (ROI) was found similar for different cooling rates of the system. Thermal stress was found developing proportional to cooling rate, which leads to minimal variation in thermal stress over time. Strain tensor was found gradually decreasing due to attenuating response of deformation gradient. In addition to that, dipping down of cryogenic temperature had prohibited the movement of molecules in the crystalline structure which had restricting the displacement gradient. It was found that uniform distribution of desired heat at different cooling rates has the ability to minimize the responses of other scaffold degradation parameters. It was found that the rates of change in stress, strain, and strain tensor were minimal at different concentrations of cryoprotectant. The present study had predicted the degradation behavior of PEC scaffold under cryogenic temperature on the basis of explicit mechanical properties. [ABSTRACT FROM AUTHOR]

Silk degumming is considered the first point in the preparation of silk-based materials since this process could modify the silk fiber and the properties of its related products. This study evaluated the differences in morphology, secondary structure, amino acid content, thermal stability, and mechanical properties of two types of raw materials, defective cocoons (DC) and silk fibrous waste (SW), degummed by chemical (C) and autoclaving (A) methods. Subsequently, silk fibroin films were prepared by dissolving each type of degummed fibers, and thermal and structural films properties were determined. The findings demonstrated that autoclaving is an efficient alternative to remove silk sericin, as the resulting fibers presented improved structural, thermal, and mechanical properties compared to those obtained by the chemical method. For films preparation, autoclave resulted in a good option, but dissolution parameters need to be adjusted for defective cocoons. Furthermore, similarities between the physicochemical properties of fibers and films from both fibrous wastes suggest that SW is a promising raw material for producing fibrous resources and regenerated silk fibroin materials. Overall, these findings suggest new recycling methods for fibrous waste and by-products generated in the silk textile production process. [ABSTRACT FROM AUTHOR]

Raw silk has made up of two constituents, filamentous (fibroin) and non-filamentous (sericin) proteins. The degumming process has been implemented to extract the fibroin by eliminating the glue-like protein sericin from the fibroin. Based on sericin elimination by the degumming process, the silk fibroin quality improves. In this investigation, natural surfactant saponin from Sapindus laurifolia Vahl. or soapnut or ritha is utilized for the muga silk cocoons degumming purpose. The two types of extraction processes (aqueous and chemical extract) of saponin from Sapindus laurifolia Vahl. or soapnut or ritha is associated with silk fibroin extraction through the degumming process. This present degumming investigation results in 22 to 23% sericin extraction within 25 min at a temperature range from 110 to 130 °C. The efficacy of extracted fibroin has been conducted with crucial parameters such as saponin concentration, degumming period, and temperature. It concludes that this novel greener process efficiently removes sericin from the fibroin fiber in its tidy state. [ABSTRACT FROM AUTHOR]

Light-driven actuators have great potential in different types of applications. However, it is still challenging to apply them in flying devices owing to their slow response, small deflection and force output and low frequency response. Herein, inspired by the structure of vine maple seeds, we report a helicopter-like rotary flying photoactuator (in response to 0.6 W/cm2 near-infrared (NIR) light) with ultrafast rotation (~7200 revolutions per minute) and rapid response (~650 ms). This photoactuator is operated based on a fundamentally different mechanism that depends on the synergistic interactions between the photothermal graphene and the hygroscopic agar/silk fibroin components, the subsequent aerodynamically favorable airscrew formation, the jet propulsion, and the aerodynamics-based flying. The soft helicopter-like photoactuator exhibits controlled flight and steering behaviors, making it promising for applications in soft robotics and other miniature devices. Light-driven actuators have great potential in different types of applications but is still challenging to apply them in flying devices owing to their slow response, small deflection and force output. Here, the authors report a rotary flying photoactuator with fast rotation and rapid response. [ABSTRACT FROM AUTHOR]

Fexible wearable sensors (FWSs), a hot research topic, have been widely used in the field of electronic skin, personal wear, electric equipment, and human–computer interaction because of their excellent flexibility, breathability, and sensing performance. However, the biocompatibility, flexibility, antibacterial activity, and breathability of FWS need to be investigated further. Herein, we propose a silk fibroin (SF)/propolis (EEP)/graphene(GR)/MXene nanocomposite-based FWS with antibacterial properties. This breathable and highly sensitive sensor was prepared by sequentially spraying GR and MXene dispersions onto SF/EEP nanocomposite fiber membranes. On testing, this sensor exhibited a wide sensing range (1–50 kPa), certain repeatability (100 cycles), high sensitivity (3 kPa−1), reliable breathability, excellent antibacterial properties, and superior biocompatibility. Moreover, this FWS can be used for human health monitoring, including motions of human fingers, elbows, knees, and other parts. Therefore, the sensor is expected to have a wide range of applications in health care detection and intelligent robots used for long-term continuous monitoring of human health. [ABSTRACT FROM AUTHOR]

Monitoring the physiological signals of people by using wearable sensors attached to the skin while they go about their daily routine is a practical approach to prevent diseases and monitor people's health status. However, conventional monitoring devices are bulky, their signals are corrupted by the noise generated by external sources, and they are prone to mechanical failure, which hinder their practical use. Herein, a mechanically durable biomaterial-based arterial pulse thin-film sensor is developed for real-time monitoring of cyclic physiological signals. A hierarchical layered material (rGO/SF/CNC) comprising reduced graphene oxide (rGO), silk fibroin (SF), and cellulose nanocrystals (CNCs) is fabricated using the spin-assisted layer-by-layer (SA-LbL) technique and thermal reduction. Thermal reduction is performed to tailor the defects in rGO, which significantly enhances its mechanical robustness and bending properties, as well as in-plane stress sensitivity, owing to a change in conductivity. The thin-film (thickness: 40.9 nm) sensor has a rapid response time (69 ms) and excellent durability exceeding 8000 cycles. Moreover, it is insensitive to strain in the orthogonal direction, which significantly reduces the noise level and dramatically increases its sensitivity. The sensor's suitability for practical use as an arterial pulse sensor for monitoring physiological signals is demonstrated. The developed thin-film flexible stress sensor has the potential to contribute toward the improvement of wearable healthcare monitoring devices and human–machine interaction. [ABSTRACT FROM AUTHOR]

In this paper, we report silk fibroin (SF) and carbon quantum dots (CQDs) nanocomposites obtained through a facile solution casting approach. The optical properties of the nanocomposites have been characterised by UV–vis absorption and photoluminescence spectroscopy. Crosslinking of SF and chemical interactions with the CQDs have been investigated by FTIR spectroscopy. In addition, water stability and degradability of the prepared composites have been investigated in terms of mass loss, important for applications in a real scenario. We observed that for a concentration of CQDs above 1%wt aggregation of nanoparticles occurs, affecting the photoluminescence of the material. The results show that the best composition in terms of photoluminescence intensity and water stability is 0.5%wt CQDs. Highlights: Silk–carbon quantum dot composites were formed via a solution casting method. Carbon quantum dots and silk fibroin were physically mixed, and no chemical bonds were detected. Luminescence quenching and loss in transparency were observed for concentrations of CQDs > 1%. [ABSTRACT FROM AUTHOR]

Non-mulberry silk fibroin (SF) has been widely explored in the field of tissue engineering because of its non-immunogenic, non-cytotoxic, and better biophysical characteristics. Being one of the non-mulberry species, Antheraea assamensis SF (AA-SF), or "muga," contributes a lot in this field. In the present study, emphasizing the prominent properties exhibited by AA-SF, we have fabricated 2D (films) and 3D (scaffolds) nanocomposite matrices (NcM) for the first time by reinforcing AA-SF nanoparticles with AA-SF solution. The results exhibited improved mechanical properties for both types of matrices. Scanning electro-microscope (SEM) and atomic force microscope (AFM) images of 2D AA-SF-NcM showed an increase in surface roughness with an increase in the concentration of the nanoparticles. Three different concentrations of the nanoparticles (0.01, 0.1, and 0.2 mg/ml) were used to fabricate the NcM in order to get an idea about the best optimized 2D and 3D models. SEM images of 3D AA-SF-NcM showed interlinking between the pores formed by the reinforced nanoparticles, thereby reducing the pore size. These variations in the matrices were further evaluated using cell proliferation assays in both 2D and 3D matrices for tissue engineering applications. HeLa cell lines were used for the study. The results demonstrated that NcM with a 0.1 mg/ml nanoparticle concentration reflects higher rates of cell proliferation and has overall improved properties as an optimized model for future tissue engineering applications. [ABSTRACT FROM AUTHOR]

Limited studies have exploited the silk fibroin potential as an oral drug delivery system. Herein, this study developed and characterized the polyethylenimine-functionalized fibroin nanoparticles (PEI-FNP) and the FNP (as a reference), loaded with furosemide, a Biopharmaceutics Classification System (BCS) class-IV drug, for oral application. Furosemide was incorporated into the systems by two different methods of co-condensation and adsorption. The optimal formulas possessed particles with sizes of ~ 200 nm, positive charges of + 60 mV, silk-II structured confirmed by infrared spectra, appropriate drug entrapment efficiencies of ~ 65%, and insignificant hemolysis action at concentrations of up to 1 mg/mL. Additionally, the PEI-FNP significantly increased the drug solubility up to 1.5-folds. Kinetically, the drug adsorption processes followed the physical type and pseudo-second-order model. In the simulated gastrointestinal condition, the particles could protect the furosemide from the stomach acidic environment. Interestingly, the particles release profiles in the intestinal condition were heavily dependent on the formulation fabrication methods. Particles prepared by the co-condensation method demonstrated an initial burst release phase, followed by a sustained release phase. Conversely, the adsorption method yielded particles with an initial sustained release phase, followed by a burst release phase. Conclusively, the PEI-FNP showed much potentials in improving the oral bioavailability of furosemide. Proven by this case, PEI-FNP could be further explored to be a potential oral delivery system for BCS class-IV drugs. [ABSTRACT FROM AUTHOR]

Silk fibroin is an important biomaterial for photonic devices in wearable systems. The functionality of such devices is inherently influenced by the stimulation from elastic deformations, which are mutually coupled through photo-elasticity. Here, we investigate the photo-elasticity of silk fibroin employing optical whispering gallery mode resonation of light at the wavelength of 1550 nm. The fabricated amorphous (Silk I) and thermally-annealed semi-crystalline structure (Silk II) silk fibroin thin film cavities display typical Q-factors of about 1.6 × 104. Photo-elastic experiments are performed tracing the TE and TM shifts of the whispering gallery mode resonances upon application of an axial strain. The strain optical coefficient K' for Silk I fibroin is found to be 0.059 ± 0.004, with the corresponding value for Silk II being 0.129 ± 0.004. Remarkably, the elastic Young's modulus, measured by Brillouin light spectroscopy, is only about 4% higher in the Silk II phase. However, differences between the two structures are pronounced regarding the photo-elastic properties due to the onset of β-sheets that dominates the Silk II structure. [ABSTRACT FROM AUTHOR]