Clinical Grade Fibroin Sutures with Bioactive Gold Clusters Enhance Surgical Wound Healing via Inflammation Modulation

Silk sutures are common in surgeries, and silk-based textiles are widely used in clinical medicine on account of their great mechanical properties and biodegradability. However, due to the lack of biocatalytic activity, silk sutures show unsatisfactory anti-inflammatory properties and healing speed. To address this constraint, we construct clinical grade bioactive gold cluster-sutures through a heterojunction. The antioxidant activity of bioactive gold cluster-sutures is ∼160 times more than that of clinical sutures. Meanwhile, the suture displays superb reactive oxygen species (ROS) scavenging, superoxide dismutase-like (SOD-like, 5 times more than the silk suture), and catalase-like (CAT-like) activities. The clusters assemble on the surface of silk through hydrogen bonding, leading to a durable catalytic and structural stability for 15 months without decay. Subsequently, the suture significantly accelerates wound healing by exerting excellent anti-inflammatory effects, improving neovascularization and collagen deposition. Clinical grade bioactive gold clusters with high bioactivity, stability, and biocompatibility hold promise for clinical translation and pave the way for other implanted biomaterials from wound healing to intelligent textiles.

Advancements in silk fibroin and silk sericin-based biomaterial applications for cancer therapy and wound dressing formulation: A comprehensive review

Silks are a class of proteins generated naturally by different arthropods, including silkworms, spiders, scorpions, mites, wasps, and bees. This review discusses the silk fibroin and silk sericin fabricated by Bombyx mori silkworm as versatile fibers. This silk fiber is predominantly composed of hydrophobic silk fibroin and hydrophilic silk sericin. Fibroin is defined as a structural protein that bestows silk with strength, while sericin is characterized as a gum-like protein, tying the two fibrous proteins together and endowing silk proteins with elasticity. Due to their versatile structures, biocompatibility, and biodegradability, they could be tailored into intricate structures to warrant particular demands. The intrinsic functional groups of both proteins enable their functionalization and cross-linking with various biomaterials to endow the matrix with favorable antioxidant and antibacterial properties. Depending on the target applications, they can be integrated with other materials to formulate nanofibrous, hydrogels, films, and micro-nanoparticles. Given the outstanding biological and controllable physicochemical features of fibroin and sericin, they could be exploited in pharmaceutical applications involving tissue engineering, wound repair, drug delivery, and cancer therapy. This review comprehensively discusses the advancements in the implementation of different formulations of silk fibroin and sericin in wound healing and drug delivery systems, particularly for cancer treatment.

Silk Sericin and Its Composite Materials with Antibacterial Properties to Enhance Wound Healing: A Review

Wound infections may disrupt the normal wound-healing process. Large amounts of antibiotics are frequently used to prevent pathogenic infections; however, this can lead to resistance development. Biomaterials possessing antimicrobial properties have promising applications for reducing antibiotic usage and promoting wound healing. Silk sericin (SS) has been increasingly explored for skin wound healing applications owing to its excellent biocompatibility and antioxidant, antimicrobial, and ultraviolet-resistant properties. In recent years, SS-based composite biomaterials with a broader antimicrobial spectrum have been extensively investigated and demonstrated favorable efficacy in promoting wound healing. This review summarizes various antimicrobial agents, including metal nanoparticles, natural extracts, and antibiotics, that have been incorporated into SS composites for wound healing and elucidates their mechanisms of action. It has been revealed that SS-based biomaterials can achieve sustained antimicrobial activity by slow-release-loaded antimicrobial agents. The antimicrobial-loaded SS composites may promote wound healing through anti-infection, anti-inflammation, hemostasis, angiogenesis, and collagen deposition. The manufacturing methods, benefits, and limitations of antimicrobial-loaded SS materials are briefly discussed. This review aims to enhance the understanding of new advances and directions in SS-based antimicrobial composites and guide future biomedical research.

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

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

Unravelling the potential of insects for medicinal purposes - A comprehensive review

Entomotherapy, the use of insects for medicinal purposes, has been practised for centuries in many countries around the world. More than 2100 edible insect species are eaten by humans, but little is known about the possibility of using these insects as a promising alternative to traditional pharmaceuticals for treating diseases. This review offers a fundamental understanding of the therapeutic applications of insects and how they might be used in medicine. In this review, 235 insect species from 15 orders are reported to be used as medicine. Hymenoptera contains the largest medicinal insect species, followed by Coleoptera, Orthoptera, Lepidoptera, and Blattodea. Scientists have examined and validated the potential uses of insects along with their products and by-products in treating various diseases, and records show that they are primarily used to treat digestive and skin disorders. Insects are known to be rich sources of bioactive compounds, explaining their therapeutic features such as anti-inflammatory, antimicrobial, antiviral, and so on. Challenges associated with the consumption of insects (entomophagy) and their therapeutic uses include regulation barriers and consumer acceptance. Moreover, the overexploitation of medicinal insects in their natural habitat has led to a population crisis, thus necessitating the investigation and development of their mass-rearing procedure. Lastly, this review suggests potential directions for developing insects used in medicine and offers advice for scientists interested in entomotherapy. In future, entomotherapy may become a sustainable and cost-effective solution for treating various ailments and has the potential to revolutionize modern medicine.

A native sericin wound dressing spun directly from silkworms enhances wound healing

It is attractive and challenging to develop a bioactive dressing based on native nondestructive sericin. Here, a native sericin wound dressing was secreted directly by silkworms bred through regulating their spinning behaviors. To be excited, our first reported wound dressing possesses original unique features of natural sericin, including natural structures and bioactivities. Besides, it has a porous fibrous network structure with a porosity of 75 %, thus achieving excellent air permeability. Moreover, the wound dressing exhibits pH-responsive degradability, softness, and super absorbency properties whose equilibrium water contents are no less than 75 % in various pH conditions. Furthermore, the sericin wound dressing demonstrates high mechanical strength, reaching 2.5 MPa tensile strength. Importantly, we confirmed good cell compatibility of sericin wound dressing that can support cell viability, proliferation, and migration for a long time. When tested in a mouse full-thickness skin wound model, the wound dressing efficiently accelerated the healing process. Our findings suggest that the sericin wound dressing has promising application and commercial value in wound repair.

Ectopic expression of sericin enables efficient production of ancient silk with structural changes in silkworm

Bombyx mori silk is a super-long natural protein fiber with a unique structure and excellent performance. Innovative silk structures with high performance are in great demand, thus resulting in an industrial bottleneck. Herein, the outer layer sericin SER3 is ectopically expressed in the posterior silk gland (PSG) in silkworms via a piggyBac-mediated transgenic approach, then secreted into the inner fibroin layer, thus generating a fiber with sericin microsomes dispersed in fibroin fibrils. The water-soluble SER3 protein secreted by PSG causes P25's detachment from the fibroin unit of the Fib-H/Fib-L/P25 polymer, and accumulation between the fibroin layer and the sericin layer. Consequently, the water solubility and stability of the fibroin-colloid in the silk glandular cavity, and the crystallinity increase, and the mechanical properties of cocoon fibers, moisture absorption and moisture liberation of the silk also improve. Meanwhile, the mutant overcomes the problems of low survival and abnormal silk gland development, thus enabling higher production efficiency of cocoon silk. In summary, we describe a silk gland transgenic target protein selection strategy to alter the silk fiber structure and to innovate its properties. This work provides an efficient and green method to produce silk fibers with new functions.

Toxicological evaluation of water-extract sericin from silkworm (Bombyx mori) in pregnant rats and their fetus during pregnancy

Sericin is a natural protein produced by the silkworm Bombyx mori, which has a wide range of biological activities and has a broad application prospect in multiple areas. However, systemic toxicity and safety assessment of sericin is still rare. This study was aimed to evaluate the toxic effects of water-extract sericin from cocoons of Bombyx mori in pregnant rats and their fetuses during pregnancy. Eighty pregnant rats were randomly divided into three treatment groups, one negative and one positive control group. The treatment groups were administered water-extract sericin solutions at doses of 1,000, 500, and 250 mg/kg, while the negative and positive control groups were administered pure water and 300 mg/kg aspirin, respectively. Rats were exposed daily by oral gavage from the seventh day of gestation for 10 consecutive days and sacrificed on the 20th day of gestation. The results showed that water-extract sericin did not induce any treatment-related changes on pregnant rats (clinical signs, body weights, food consumption, ovarian and uterine weights) and fetuses (body weights, body lengths, tail lengths, visceral, and skeletal development). The no-observed-adverse-effect-level (NOAEL) of sericin was determined to be 1,000 mg/kg body weight in rats. These results indicated that water-extract sericin is of low teratogenic potential under the experimental conditions of this study.

Study of the Antioxidative Effects of Bombyx mori Silk Sericin in Cultures of Murine Retinal Photoreceptor Cells

The availability of natural substances able to fulfill the role of antioxidants in a physiologic environment is important for the development of therapies against diseases associated with excessive production of reactive oxygen species and ensuing oxidative stress. Antioxidant properties have been reported episodically for sericin, a proteinaceous constituent of the silk thread in the cocoons generated by the larvae of the Lepidoptera order. We investigated the sericin fractions isolated from the cocoons spun by the domesticated (Bombyx mori) silkworm. Three fractions were isolated and evaluated, including two peptidoid fractions, the crude sericin and the purified (dialyzed) sericin, and the non-peptidoid methanolic extract of the crude fraction. When subjected to Trolox equivalent antioxidant capacity (TEAC) assay, the extract showed much higher antioxidant capacity as compared to the crude or purified sericin fractions. The three fractions were also evaluated in cultures of murine retinal photoreceptor cells (661 W), a cell line that is highly susceptible to oxidants and is crucially involved in the retinopathies primarily caused by oxidative stress. The extract displayed a significant dose-dependent protective effect on the cultured cells exposed to hydrogen peroxide. In identical conditions, the crude sericin showed a certain level of antioxidative activity at a higher concentration, while the purified sericin did not show any activity. We concluded that the non-peptidoid components accompanying sericin were chiefly responsible for the previously reported antioxidant capacity associated with sericin fractions, a conclusion supported by the qualitative detection of flavonoids in the extract but not in the purified sericin fraction.

The exploration and utilization of functional substances in edible insects: a review

Edible insects as food have been considered as a core future protein source. Not only are edible insects abundant in nutrient value, but also have numbers of functional substances, which could provide a multiple valuable benefits for humans. This review examines and summarizes the functional substances in edible insects and their special effects for people, as well as the use and prospects for these functional substances. There are many functional substances in edible insects, such as antimicrobial peptides, interferon, sex attractant hormones, cordycepin, active polysaccharides, microelement, chitin/chitosan, steroidal material, vitamin, lecithin, etc., which could provide multiple benefits for human beings. These special functional substances could help people enhance immunity, inhibit tumor, regulate intestinal function, relieve fatigue, anti oxidation, protect against colds, improve sleeping, promote the growth and development, as well as reducing blood sugar and blood pressure, among others. According to these valuable efficacies, the functional substances extracted from edible insects can be exploited mainly in three ways: edible insects are used to discover new medicines or health care products for people; and edible insects are applied in chemical, agricultural, food technology, pollutant treatment and textile sectors; as well as being consumed as animal feedstuff for livestock and other animals, which indirectly meet the different requirements for humans. Currently, edible insects have generated global interest to be developed as different forms of products and has promoted more research and development. However, pupae and larvae are still the main consumption ways in the market, which is unacceptable to most people. It is expected that the edible insect industry would be prosperous and sustainable by integrating the power of beneficial policies and regulations, huge consumer demand and proper strategies of promotion and production.

Graphical Abstract

Silkworm Protein-Derived Nitrogen-Doped Carbon-Coated Li[Ni0.8Co0.15Al0.05]O2 for Lithium-Ion Batteries

Li[Ni0.8Co0.15Al0.05]O2 (NCA) is a cathode material for lithium-ion batteries and has high power density and capacity. However, this material has disadvantages such as structural instability and short lifespan. To address these issues, herein, we explore the impact of N-doped carbon wrapping on NCA. Sericin, an easily obtained carbon- and nitrogen-rich component of silk cocoons, is utilized as the precursor material. The electrochemical performance evaluation of N-doped carbon-coated NCA shows that the capacity retention of 0.3 NC@NCA at 1C current density is 69.83% after 200 cycles, which is about 19% higher than the 50.65% capacity retention of bare NCA. The results reveal that the sericin-resultant N-doped carbon surface wrapping improves the cycling stability of NC@NCA.

Enhancing the In Vitro Biological Activity of Degraded Silk Sericin and Its Analog Metabolites

Two sericins of high and low molecular weight (HS and LS) were prepared from commercial silkworm cocoon silk with a boiling water and Ca(OH)₂ solution with ultrasonic treatments, respectively. This study first investigated the release concentration of the two abovementioned sericins in simulated saliva, gastric juice, and intestinal juice (pH 6.8, 2.0, and 7.4, respectively) within 10 h. The results showed that the order of sericin release rate and its amount in the simulated environment was gastric juice > saliva > intestinal juice. Second, the molecular weights of both sericin metabolites formed by in vitro enzymatic degradation were lower than 15 kDa. The α-glucosidase inhibitory activities of both sericins and their analog metabolites were positively correlated with their concentrations. The IC₅₀ values of the HS- and LS-derived metabolites were 1.02 ± 0.12 mg/mL and 0.91 ± 0.15 mg/mL, respectively, which were five to seven times lower than those of both original sericins. The total antioxidant capacities and hydroxyl radical scavenging capacities of both metabolites were enhanced by one- to three-fold compared with HS and LS. These results indicate that both sericins, regardless of molecular size, have significantly enhanced antioxidant, superoxide free radical scavenging, and glycosidase inhibitory activities after simulated metabolism, and that LS is better than HS regardless of simulated digestion. These results confirm that sericin is important in the sustainable development and utilization of silk resources, especially the reduction in environmental pollution, and provides new ideas for the development of adjuvant treatments for diabetes and the development of foods with anti-hyperglycemic functions.

Anti-Herpes Simplex Virus Efficacy of Silk Cocoon, Silkworm Pupa and Non-Sericin Extracts

Herpes simplex virus (HSV) infections are prevalent worldwide and are the cause of life- threatening diseases. Standard treatment with antiviral drugs, such as acyclovir, could prevent serious complications; however, resistance has been reported specifically among immunocompromised patients. Therefore, the development of an alternative approach is needed. The silk cocoon derived from silkworm, Bombyx mori, has been recognized for its broad-spectrum biological activity, including antiviral activity; however, its effects against HSV infection are unknown. In this study, we investigated the inhibitory effects of silk extracts derived from the cocoon shell, silk cocoon, silkworm pupa and non-sericin extract, on blocking HSV-1 and HSV-2 binding to host cells, resulting in the inhibition of the virus infection in Vero cells. Non-sericin extract demonstrated the greatest effectiveness on inhibiting HSV-1 and HSV-2 binding activity. Moreover, the virucidal effect to inactivate HSV-1 and HSV-2 was determined and revealed that non-sericin extract also exerted the highest potential activity. Using the treatment of non-sericin extract in HSV-2-infected HeLa cells could significantly lower the HSV-induced cell death and prevent inflammation via lowering the inflammatory cytokine gene expression. The non-sericin extract was analyzed for its bioactive compounds in which gallic acid, flavonoid and xanthophyll were identified, and might have partially contributed to its antiviral activity. The finding in our study suggested the potential of silk extract as an alternative therapeutic treatment for HSV infection.

Fabrication and Characterization of Human Serum Albumin Particles Loaded with Non-Sericin Extract Obtained from Silk Cocoon as a Carrier System for Hydrophobic Substances

Non-sericin (NS) extract was produced from the ethanolic extract of Bombyx mori silk cocoons. This extract is composed of both carotenoids and flavonoids. Many of these compounds are composed of substances of poor aqueous solubility. Thus, this study focused on the development of a carrier system created from biocompatible and biodegradable materials to improve the biological activity of NS extracts. Accordingly, NS was incorporated into human serum albumin template particles with MnCO₃ (NS-HSA MPs) by loading NS into the preformed HAS-MnCO₃ microparticles using the coprecipitation crosslinking dissolution technique (CCD-technique). After crosslinking and template dissolution steps, the NS loaded HSA particles are negatively charged, have a size ranging from 0.8 to 0.9 µm, and are peanut shaped. The degree of encapsulation efficiency ranged from 7% to 57% depending on the initial NS concentration and the steps of adsorption. In addition, NS-HSA MPs were taken up by human lung adenocarcinoma (A549 cell) for 24 h. The promotion of cellular uptake was evaluated by flow cytometry and the results produced 99% fluorescent stained cells. Moreover, the results from CLSM and 3D fluorescence imaging confirmed particle localization in the cells. Interestingly, NS-HSA MPs could not induce inflammation through nitric oxide production from macrophage RAW264.7 cells. This is the first study involving the loading of non-sericin extracts into HSA MPs by CCD technique to enhance the bioavailability and biological effects of NS. Therefore, HSA MPs could be utilized as a carrier system for hydrophobic substances targeting cells with albumin receptors.

The flavonoid-rich ethanolic extract from the green cocoon shell of silkworm has excellent antioxidation, glucosidase inhibition, and cell protective effects in vitro

The green cocoon shell of a novel variety of silkworm, Bombyx mori, is rich in two types of quercetin and kaempferol flavonoids. The aim of this study was to identify these flavonoids in the ethanolic extract (EE) from green cocoons and develop EE applications in healthy foods. The experimental results indicated that the amount of total amino acids in EE was 27.06%. The flavonoids in EE are presented in quercetin and kaempferol glycosides. The total amount of the two aglycones was 33.42 ± 0.08 mg/g. The IC50 values of 2,2-diphenyl-1-picrylhydrazyl (DPPH), 1,2'-azino-bis (3-ethylbenzthiazoline-6-sulphonicacid) (ABTS), and hydroxyl radical scavenging abilities were 296.95 ± 13.24 μg/mL, 94.31 ± 9.13 μg/mL, and 9.21 ± 0.15 mg/mL, respectively. The IC50 values of the inhibitory activities of α-amylase and α-glucosidase were 37.57 ± 6.45 μg/mL and 212.69 ± 22.94 μg/mL, respectively. EE also reduced the level of reactive oxygen species (ROS) and oxidative stress in L02 cells induced by high glucose levels. It also effectively decreased the content of 8-hydroxyl deoxyguanosine (8-OHdG), nuclear factor κB (NF-κB), and tumour necrosis factor alpha (TNF-α) in cells with a good dose effect. These results clearly indicated that the flavonoid-rich EE with excellent antioxidant and glucosidase inhibition abilities significantly reduced the damage to cells caused by oxidative stress and inflammatory reactions. It is suggested that EE might serve as useful functional foods for the treatment of related diseases induced by oxidative stress such as diabetes mellitus.

Acid Hydrolyzed Silk Peptide Consumption Improves Anti-Diabetic Symptoms by Potentiating Insulin Secretion and Preventing Gut Microbiome Dysbiosis in Non-Obese Type 2 Diabetic Animals

: Silk fibroin hydrolysates have been reported to reduce hyperglycemia, but the mechanism has not been determined in Asian type 2 diabetes (T2DM). We hypothesized that the consumption of acid hydrolyzed silk peptides (SPs) alleviates hyperglycemia by improving insulin sensitivity and subsequently normalizing glucose-stimulated insulin secretion in T2DM. We investigated this hypothesis in a partial pancreatectomized (Px) rat model. Px rats was assigned randomly to the following six groups and fed assigned diet for 8 weeks: the Px-CON (0.5 g/kg/day dextrin), the SP-L (0.05 g/kg/day), the SP-M (0.1 g/kg/day), the SP-H (0.5 g/kg/day), the positive-CON (30 mg/kg/day metformin), or the normal-CON (sham-operated rats; 0.5 g/kg/day dextrin). SPs contained high levels of glycine, alanine, and serine. We found SPs dose-dependently increased food efficiency and body weight gain in Px rats. Animals in the Px-control group rats exhibited lower glucose metabolism, as evidenced by impaired glucose-stimulated insulin secretion coupled with impaired insulin sensitivity, and reduced bone mineral density (BMD) and lean body mass (LBM), compared to normal-CON. SPs and metformin similarly partially protected against Px-induced BMD loss in the lumbar spine and femur. Px-induced decreases in LBM were dose-dependently prevented by SPs, and muscle forces in the SP-M and SP-H groups were maintained at the normal-CON level. Glucose tolerance was dose-dependently improved by SPs as determined by oral glucose tolerance and oral maltose tolerance tests, and glucose tolerances were similar in the SP-H and positive-CON groups. Insulin tolerance, an index of insulin sensitivity, was dose-dependently enhanced by SPs, and the SP-H group exhibited better insulin tolerance than the positive-CON group as determined by intraperitoneal insulin sensitivity testing. Insulin secretory capacity assessed using a hyperglycemic clamp improved in the following order: Px-control <SA-L <SA-M <positive-control <SA-H <normal-control. SP-M prevented gut microbiota dysbiosis. In conclusion, SPs administered at 0.1-0.5 g/kg/day improved glucose regulation by potentiating both insulin secretion and insulin sensitivity in non-obese T2DM rats.

Salt-induced silk gel-derived N and trace Fe co-doped 3D porous carbon as an oxygen reduction catalyst in microbial fuel cells

Inexpensive and high-efficiency oxygen reduction reaction (ORR) catalysts play a significant role in achieving practical applications of microbial fuel cells (MFCs). Hence, herein, novel nitrogen (N) and trace iron (Fe) co-doped three-dimensional (3D) porous carbon (NFe_x-C) was synthesized as an excellent ORR catalyst from an interesting salt-induced silk gel, which was beneficial to the spontaneously formation of porosity and boosted the ORR activity. Among the series of NFe_x-C, NFe_0.5-C (1.20% N-ORR/C, 0.07 at% Fe) possessed a higher specific surface area (538.94 m² g^-1) and pore volume (2.158 cm³ g^-1). Note that NFe_0.5-C exhibited a significantly higher positive initial potential (0.274 V vs. Ag/AgCl) and half-wave potential (0.095 V vs. Ag/AgCl) than other catalysts and commercial Pt/C (20 wt%); this implied that it possessed prominent ORR catalytic activity. In the MFC tests, the output-voltage and maximum power density of NFe_0.5-C were enhanced to 517.37 ± 7.87 mV and 605.35 ± 15.39 mW m^-2, respectively. Moreover, NFe_0.5-C (0.15 $ g^-1) exhibits excellent anti-poisoning ability and is thousands of times cheaper than commercial Pt/C (20 wt%, 220.04 $ g^-1); therefore, NFe_0.5-C should be a prospective catalyst to substitute precious commercial Pt/C in MFCs and even for application in other types of fuel cells.

Therapeutic effects of ethanolic extract from the green cocoon shell of silkworm Bombyx mori on type 2 diabetic mice and its hypoglycaemic mechanism

Diabetes mellitus is a clinically complex disease characterized by hyperglycaemia with disturbances in carbohydrate, fat and protein metabolism. The aim of this study was to determine the therapeutic effect of ethanolic extract (EE) from the green cocoon sericin layer of silkworm Bombyx mori on mice with type 2 diabetes mellitus (T2DM) and its hypoglycaemic mechanisms. The results showed that oral EE for 7 weeks had significant ameliorative effects on all the biochemical parameters studied in vivo. The levels of oral glucose tolerance and insulin tolerance were significantly improved. The hypoglycaemic rate in the 350 mg kg^-1 high dosage group was 39.38%. The levels of nuclear factor kappa B (NFκB), interleukin 6 (IL-6) and tumour necrosis factor alpha (TNF-α) in the high dosage EE-treated group were significantly reduced, while activities of antioxidant enzymes superoxide dismutase (SOD) and glutathione peroxidase (GSH-Px) were obviously increased. The islet area and the number of insulin-positive beta cells increased significantly in the high dose group. Furthermore, expression levels of insulin receptor (IR), insulin receptor substrate (IRS), phosphatidylinositide 3-kinase (PI3K), p-Akt and phospho-glycogen synthase kinase-3β (p-GSK3β) involved in insulin signalling were increased. Adenosine 5'-monophosphate-activated protein kinase (AMPK) and glucose transporter 4 (GLUT4) also were activated to regulate glucose metabolism in EE-treated groups. The levels of glucose 6-phosphatase (G6pase) and phosphoenolpyruvate carboxykinase (PEPCK) decreased, while the glucokinase (GK) level increased to promote glycolysis. The results clearly indicated that oral EE, especially at a high dose, could improve the glucose metabolism of T2DM by reducing inflammatory reactions, enhancing the antioxidant capacity and insulin sensitivity, and regulating the balance between glycolysis and gluconeogenesis, which means that EE has potential ameliorative effects on T2DM mice.

Thermosensitive Behavior and Super-Antibacterial Properties of Cotton Fabrics Modified with a Sercin-NIPAAm-AgNPs Interpenetrating Polymer Network Hydrogel

Poly(N-isopropylacrylamide) (PNIPAAm), sericin (SS), and silver nitrate were combined to prepare an interpenetrating network (IPN) hydrogel having dual functions of temperature sensitivity and antibacterial properties. The structure and size of AgNPs in such an IPN hydrogel were characterized by the Fourier Transform Infrared spectrum (FT-IR), X-ray powder diffraction (XRD) and Transmission Electron Microscope (TEM), and the thermal properties of the IPN hydrogel were characterized by Differential Scanning Calorimetry (DSC). Based on XRD patterns, Ag⁺ was successfully reduced to Ag⁰ by SS. It was observed by TEM that the particle size of silver particles was lower than 100 nm. The glass transition temperature (Tg) of IPN hydrogel was better than that of the PNIPAAm/AgNPs hydrogels, and lower critical solution temperature (LCST) values of the IPN hydrogel were obtained by DSC i.e. 31 °C. The thermal stability of the IPN hydrogel was successfully determined by the TGA. This IPN hydrogel was then used to modify the cotton fabrics by the "impregnation" method using glutaraldehyde (GA) as the cross-linking agent. The structures and properties of IPN hydrogel modified cotton fabric were characterized by scanning electron microscopy (SEM), FT-IR, and the thermogravimetry analysis (TGA). The results show that NIPAAm was successfully polymerized into PNIPAAm, and that there were neglected new groups in the hydrogel IPN. The IPN hydrogel was then successfully grafted onto cotton fabrics. SEM observations showed that the IPN hydrogel formed a membrane structure between the fibers, and improved the compactness of the fibers. At the temperature close to LCST (≈31 °C), the entire system was easily able to absorb water molecules. However, the hydrophilicity tended to decrease when the temperature was higher or lower than the LCST. The antibacterial rates of the modified cotton fabric against S. aureus and E. coli were as high as 99%.

Silk nanoparticles: from inert supports to bioactive natural carriers for drug delivery

Silk proteins have been studied and employed for the production of drug delivery (nano)systems. They show excellent biocompatibility, controllable biodegradability and non-immunogenicity and, if needed, their properties can be modulated by blending with other polymers. Silk fibroin (SF), which forms the inner core of silk, is a (bio)material officially recognized by the Food and Drug Administration for human applications. Conversely, the potential of silk sericin (SS), which forms the external shell of silk, could still be considered under evaluation. At the best of our knowledge, nanoparticles based on silk sericin "alone" cannot be produced, due to its physicochemical instability influenced by extreme pH, high water solubility and temperature; for these reasons, it almost always needs to be combined with other polymers for the development of drug delivery systems. In this review, we focused on silk proteins as bioactive natural carriers, since they show not only optimal features as inert excipients, but also remarkable intrinsic biological activities. SF has anti-inflammatory properties, while SS presents antioxidant, anti-tyrosine, anti-aging, anti-elastase and anti-bacterial features. Here, we give an overview on SF or SS silk-based nanosystems, with particular attention on the production techniques.

Identification and quantification and antioxidant activity of flavonoids in different strains of silk cocoon, Bombyx mori

Silk cocoon is produced from silkworm (Bombyx mori) to protect itself from outer environment. Various strains of cocoon contain different forms and amounts of flavonoids, which may affect on their antioxidant activity. Moreover, the extraction method would influence the amount of flavonoids extracted. Therefore, the objectives of this study were to identify and quantify the flavonoids in 3 strains of bivoltine Bombyx mori silk cocoon (Chul 1/1; white cocoon, Chul 3/2; greenish cocoon, and Chul 4/2; yellow cocoon) extracted by 6 different solvents including acetone, ethyl acetate, dimethyl sulfoxide (DMSO), ethanol, methanol, and purified water. The flavonoids extracted were identified and quantified by liquid chromatography-mass spectrometry (LC-MS). The antioxidant activity of flavonoids extracted was also investigated by visible spectroscopy at 517 nm. The results showed that Chul 3/2 silk cocoon contained the highest amount of flavonoids. Purified water seemed to be the best solvent that preserved most antioxidant activity of the flavonoids extracted. Flavonoids in Chul 1/1 and Chul 4/2 silk cocoon were rarely found, however they contained some antioxidant activities. The data from this study can provide basic information for flavonoid extraction from silk cocoon which can also apply for other flavonoid-containing natural biomaterials.

Effects of alkyl polyglycoside (APG) on Bombyx mori silk degumming and the mechanical properties of silk fibroin fibre

Alkyl polyglycoside (APG), a nonionic surfactant, is often considered to be a green surfactant and is synthesized using glucose and long chain fatty alcohols. It is used as a degumming agent of Bombyx mori silk fibre in this study for the first time. We studied APG systematically in comparison to the traditional degumming methods, such as aqueous solutions of sodium carbonate (Na₂CO₃) and neutral soap (NS). After repeatedly boiling silk fibres in an aqueous solution of 0.25% APG three times for 30min and using a bath ratio of 1:90-120 (g/mL), sericin was completely removed from the fibre. SDS-PAGE showed that the degumming in APG did not induce an evident breakage of the silk fibroin peptide chains, including the light chain and P25 protein. The tensile properties, thermal analysis, and scanning electron microscopic (SEM) observation of the degummed fibroin fibre all show that APG is a degumming agent similar to NS and far superior to Na₂CO₃. These results indicate that APG is an environment-friendly silk degumming/refining agent in the silk textile industry and in the manufacture of silk floss quilts.

Processing and characterization of silk sericin from Bombyx mori and its application in biomaterials and biomedicines

Bombyx mori silk is composed of 60-80% fibroin, 15-35% sericin and 1-5% non-sericin component including wax, pigments, sugars and other impurities. For two decades, the protein-based silk fibroin was extensively used in the research and development of medical biomaterials and biomedicines. Sericin is frequently ignored and abandoned as a byproduct or waste in the processing of traditional silk fabrics, silk floss or modern silk biomaterials. However, similar to fibroin, sericin is not only a highly useful biological material, but also a lot of biological activity. Moreover, the non-sericin component present with sericin in the cocoon shell also has a strong biological activity. In this review, the extraction and recovery methods of sericin and the non-sericin component from the cocoon layer are reported, and their composition, properties and biological activity are described to produce a comprehensive report on biomedical materials and biological drugs. In addition, related problems or concerns present in the research and development of sericin are discussed, and a potential application of sericin in sustainable development is also presented.

A glowing antioxidant from tasar silk cocoon

In this study, a fluorophore can be easily localized inside animal cell line H9c2 using a novel N-TER™ based strategy, and the internalized fluorophore acts both as a fluorescent dye and as an antioxidant.

Inhibition of the flavonoid extract from silkworm cocoons on DMBA/UVB-induced skin damage and tumor promotion in BALB/c mice

Exposure of the skin to ultraviolet B radiation causes oxidative stress that results in sunburn, photoaging, and skin cancer.

Text mining of the classical medical literature for medicines that show potential in diabetic nephropathy

Objectives. To apply modern text-mining methods to identify candidate herbs and formulae for the treatment of diabetic nephropathy. Methods. The method we developed includes three steps: (1) identification of candidate ancient terms; (2) systemic search and assessment of medical records written in classical Chinese; (3) preliminary evaluation of the effect and safety of candidates. Results. Ancient terms Xia Xiao, Shen Xiao, and Xiao Shen were determined as the most likely to correspond with diabetic nephropathy and used in text mining. A total of 80 Chinese formulae for treating conditions congruent with diabetic nephropathy recorded in medical books from Tang Dynasty to Qing Dynasty were collected. Sao si tang (also called Reeling Silk Decoction) was chosen to show the process of preliminary evaluation of the candidates. It had promising potential for development as new agent for the treatment of diabetic nephropathy. However, further investigations about the safety to patients with renal insufficiency are still needed. Conclusions. The methods developed in this study offer a targeted approach to identifying traditional herbs and/or formulae as candidates for further investigation in the search for new drugs for modern disease. However, more effort is still required to improve our techniques, especially with regard to compound formulae.

Effect of Strongly Alkaline Electrolyzed Water on Silk Degumming and the Physical Properties of the Fibroin Fiber

Strongly alkaline electrolyzed water (SAEW) was prepared by electrolysis of tap water in a laboratory-made water electrolyzer. The pH of stored SAEW was stable for more than one month. The hardness of the electrolyzed water was 30% lower and the Na⁺ concentration was 18% higher than those of the tap water. Silkworm cocoon shells were boiled in pH 11.50 SAEW at a ratio of 1∶40∼80 (W/V) for 20 min and the sericin layers around the silk fibroin fibers were removed completely. The tensile properties and thermal decomposition temperature of a single filament of silk fibroin obtained by the SAEW method were almost the same as those for the fiber obtained by the neutral soap, and much higher than those for the fiber obtained by Na₂CO₃ degumming. The results demonstrate that SAEW is an environmentally friendly and pollution-free silk degumming agent that allows highly efficient, low cost recovery of sericin.

Sericins exhibit ROS-scavenging, anti-tyrosinase, anti-elastase, and in vitro immunomodulatory activities

Some biological properties of Bombyx mori sericins from twenty strains were investigated, fourteen fed with artificial diet, two with fresh mulberry leaves and four with both diets. Sericin exhibited ROS-scavenging, anti-tyrosinase and anti-elastase properties, the strain significantly influenced these properties, while diet only influenced the anti-tyrosinase activity. Sericins were clustered into 5 groups and one sericin from each group was further studied: sericins showed anti-proliferative activity on in vitro stimulated peripheral blood mononuclear cells; some strains decreased in vitro secretion of IFNγ, while no effects were observed on TNFα and IL10 release. Therefore, a mixture of sericins extracted from the most promising strains may be useful for dermatological and cosmetic use.