Pupae Research Articles

Aqueous and chemical extraction of saponin of Acacia concinna (Willd.) Dc.: An effective Bio-surfactant solution to extract silk fibroin from muga silk cocoons

• Extraction of silk fibroin by utilizing bio-surfactant saponin. • Aqueous and Chemical extraction process utilized to extract silk fibroin. • Acacia concinna (Willd.) Dc. is utilized for the extraction process. • Formation of micelles to eliminate the sericin from silk fibroin . • Analysis of the degummed fibers properties by SEM, XRD, TGA/DSC, tensile strength. Silk fibroin is generated from the silkworms and enclosed in a glue-like protein called sericin. In recent years, silk fibroin has been recognized for its significant biomedical significance, especially in tissue engineering, wound dressing, and drug and gene delivery. Numerous degumming methods have already been employed to extract the fibroin protein from the silk cocoons, which discharges large volumes of toxic admixture of sericin and chemicals through effluents. A sustainable, cleaner and environmentally promising silk fibroin extraction technique of muga silk have been investigated by utilizing the bio-surfactant saponin that has been isolated from the Acacia concinna (Willd.) Dc. in two different extraction processes aqueous extraction and chemical extraction. The degumming efficacy has been performed with respect to saponin concentration, degumming period, and temperature. After the completion of the degumming process, the silk samples were subjected to examination by SEM, XRD, TGA/DSC, and mechanical (tensile) capacity study. This novel and greener degumming treatment was potentially applied to extract the silk fibroin from the silk cocoons in a cleaned state. The toxicity level generated in the degumming process was observed to be very low owing to the adoption of non-toxic chemicals. Overall study ascertains about can be an effective usage of the extracted silk fibroin for medical applications because of its low toxicity.

Identification and characterization of sericin5 reveals non-cocoon silk sericin components with high β-sheet content and adhesive strength

Sericins are glue proteins on the surface of silk fibers. Four sericins have been characterized in silkworm, namely sericin1 (Ser1), sericin2 (Ser2), sericin3 (Ser3), and sericin4 (Ser4). In this study, we report a novel sericin, sericin5 (Ser5), which exists only in non-cocoon silk. We describe the sequence, exon-intron structure, and translation products of Ser5 in Bombyx mori. The Ser5 gene is approximately 22-kb long and comprises 16 exons. Ser5 protein has a size of 260 kDa, as determined by SDS-PAGE, western blot, and LC-MS/MS. Immunofluorescence analysis revealed that Ser5 co-localizes with Ser1 in the sericin layer. The expression pattern of Ser5 was detected at the transcriptional and translational levels. We systematically analyzed and compared the amino acid composition, repeat regions, and hydrophilicity of silkworm sericins. Morphological observations showed that non-cocoon silk had more sericin than cocoon silk. Circular dichroism spectra revealed that non-cocoon silk sericin contained more β-sheet structures than cocoon silk sericin. In addition, we found that the hydrophilicity and adhesive strength of native sericin increases gradually from the inner layer to the outer layer. This research enhances our understanding of various sericins from cocoon silk and non-cocoon silk with regard to their expression patterns, hydrophilicity, secondary structure and adhesive performances. Statement of significanceSericin is a natural biomaterial with diverse biological properties, which has long been used as tissue engineering and biomedical applications. However, the composition and distribution of sericins in different kinds of silk are still uncertain, and the properties difference between sericins have not yet been reported. Our study makes a significant contribution to the literature as it identifies the sequence, composition, hydrophilicity and adhesive property of sericins. Moreover, it provides key insights into the structure-function and function-distribution relationships associated with sericins. We believe that this study will arouse the interest to the readership of your journal as it identifies the new complete sequence of sericin and revealed the composition and properties of sericin, thus highlighting their future potentials applications in both the biomaterial and technical fields.

Economic Analysis of Sericulture in Nagpur District, India: Environmental Impact and Sustainable Management

The study is an attempt to assess the silkworm cocoon production and its profitability in Nagpur district of Maharashtra through structured survey during 2017-18 with a view to know socio economic characteristics of mulberry growers such as family type, education, family size, education status, land use pattern, and cropping pattern etc. were studied. Data pertains to the year 2017-18. The data were collected by using the multipurpose sampling design. The study was based on total 60 mulberry growers. It states that, the average size of the family worked out to 5 individuals per households. Out of which 2 mens, 2 women and 1 children, Where as 6.66% illiterate and 93.34% are literate. The possession of average land holding was 2.06 hectares. The gross cropped area was 3.73 hectares. The cropping intensity was found to be 195.28 per cent. In 2017-18 total area under mulberry cultivation in Nagpur district is 285 acre and per acre production of silk cocoon is 1.666 kg/yr. (District Sericulture Office, Nagpur).

Novel ultrasonic-assisted cleaner technology for cocoon brushing at low temperature

Cocoon brushing is a vitally important process in silk reeling, it closely relates to raw silk quality and reeling efficiency. In this research, an ultrasonic-assisted cocoon brushing process is proposed, which can achieve cocoon reeling and silk cleaning at lower temperature and alleviate the problem of using excessive temperature to cocoon brushing in silk reeling factories. The cocoon brushing effect of different treatment conditions is investigated by fuzzy orthogonal method to obtain the optimal process: ultrasonic temperature 80 °C, ultrasonic time 40 s, ultrasonic power 144 W, cocoon cooking time 3 min. Compared with the conventional process, the total number of cocoon brushing is reduced by 4.75 times, the reelability percentage is heightened 11.39% and the rushing upon cocoons per myriameter is lessened 2.53 times. After ultrasonic treatment, the secondary structure and thermal stability of raw silk are not change. The sericin distribution is more uniform and the mechanical properties are improved to a certain extent. The temperature of this process is about 15 °C lower than the silk reeling factory and it can save 93 MJ for 1 kg of raw silk per reeling. Results show that ultrasonic can be used to develop an green process for cocoon brushing, which may provide a technical reference for the silk environmental protection production.

An effective Bio-surfactant solution to extract silk fibroin from muga silk cocoons

An effective Bio-surfactant solution to extract silk fibroin from muga silk cocoons

Novel Dry Spinning Process of Natural Macromolecules for Sustainable Fiber Material -1- Proof of the Concept Using Silk Fibroin.

Researchers around the world are developing technologies to minimize carbon dioxide emissions or carbon neutrality in various fields. In this study, the dry spinning of regenerated silk fibroin (RSF) was achieved as a proof of concept for a process using ionic liquids as dissolution aids and plasticizers in developing natural polymeric materials. A dry spinning equipment system combining a stainless-steel syringe and a brushless motor was built to generate fiber compacts from a dope of silk fibroin obtained by degumming silkworm silk cocoons and ionic liquid 1-hexyl-3-methyl-imidazolium chloride ([HMIM][Cl]) according to a general method. The maximum stress and maximum elongation of the RSF fibers were 159.9 MPa and 31.5%, respectively. RSF fibers containing ionic liquids have a homogeneous internal structure according to morphological investigations. Elemental analysis of fiber cross sections revealed the homogeneous distribution of nonvolatile ionic liquid [HMIM][Cl] in RSF fibers. Furthermore, the removal of ionic liquids from RSF fibers through impregnation washing with organic solvents was verified to enhance industrial applications. Tensile testing showed that the fiber strength could be maintained even after removing the ionic liquid. Thermogravimetric analysis results show that the organic solvent 1,1,1,3,3,3-hexafluoro-2-propanol is chemically coordinated to silk fibroin and, as a natural polymer, can withstand heat up to 250 °C.

Crystallite Shapes and Functional Data Analysis of Silk forms using X-ray Diffraction: Microwave Irradiation Effects

The silk cocoon of Bombyx mori, fiber, and thin films were considered in our study. The pure silk thin films were prepared by extracting silk from Bombyx mori cocoons. These samples were treated with microwave irradiation at different intervals, and X-ray diffraction data of these samples were obtained. XRD data of these samples were used as an essential input to compute crystallite size along with different Bragg reflections. Employing different statistical tools, the shape of the ordered region for different samples was obtained, and these shapes were analyzed and concluded that the obtained shapes are not ellipsoidal as assumed by earlier researchers and these are multi-shaped and strongly depend on the direction of Bragg reflections. The functional data analysis was also carried out to determine the correlation between physical and microstructural parameters.

Silk Fiber Multiwalled Carbon Nanotube-Based Micro-/Nanofiber Composite as a Conductive Fiber and a Force Sensor.

Silk cocoon fibers (SFs) are natural polymers that are made up of fibroin protein. These natural fibers have higher mechanical stability and good elasticity properties. In this work, we coated multiwalled carbon nanotubes (MWCNTs) on the surface of SFs using a simple stirring technique with vinegar as the medium. This SF-MWCNT micro-/nanofiber composite was prepared without any adhesives. The characterization results revealed that the SF-MWCNT micro-/nanofiber composite exhibited excellent electrical conductivity (995 Ω cm–1), tensile strength (up to 200% greater elongation), and durability characteristics. In addition, this micro-/nanofiber composite shows a change in resistance from 1450 to 960 Ω cm–1 for an applied mechanical force of 0.3–1 N kg–1. Based on our findings, SF-MWCNT micro-/nanofiber composite-based conductive fibers (CFs) and force sensors (FSs) were developed.

In-situ preparation of silk-cocoon derived carbon and LiFePO4 nanocomposite as cathode material for Li-ion battery

We report a natural fiber template method for the synthesis of lithium iron phosphate carbonized silk cocoon (LFP-CS), as cathode electrode material for lithium-ion batteries. Bombyx-mori silk-cocoons was used as template and heated along with LFP precursor to obtain a carbonized silk carbon network around LFP. The X-ray powder diffraction (XRD) shows a well crystalline single-phase olivine structured LFP-CS nanoparticle. Scanning electron microscope (SEM) and Transmission electron microscopy (TEM) revealed the spherical morphology of LFP nanoparticle, which was absorbed on the surface and sub-surface of the cocoon fibers. The LFP nanoparticles were uniformly dispersed within the layer of carbon sheet, forming conductive carbon network between individual particles. The electrochemical study revealed that the LFP-CS has a capacity of 163 mAh/g at 0.1C and 123 mAh/g at 5C rate with excellent cycle performance. Apparently, conductive carbon network formed could also increase the electrochemical performance of the electrode material.

Structure and properties of flat cocoon silk after silk reeling

Silk is obtained mostly from oval cocoons. In this paper, the flat cocoons were obtained by changing the silking environment of Bombyx mori silkworms. Then the appropriate method was used to reel the flat cocoons. The structure, thermal and mechanical properties of flat cocoon silk (FCS) after silk reeling and degumming were studied. The experimental results have shown that flat cocoon silk has the same main composition and similar thermal performance as that of common cocoon silk (CCS), but the sericin distribution on the surface of FCS is more uniform, the crystallinity degree of the FCS (53.77%) is slightly higher than that of the CCS (50.02%), and the cross-sectional areas of the FCS before and after degumming are smaller than those of the CCS. Before degumming, the stress of FCS is about 1% higher than that of CCS, the initial modulus is about 4.7% higher, and the strain is about 10.7% lower. After degumming, the stress of FCS is about 2.7% higher than that of CCS, the initial modulus is about 7.8% higher, and the strain is about 31.3% lower. The results have shown that FCS after silk reeling has application performance close to or even better than that of CCS.

Tyrosine Hydroxylase and DOPA Decarboxylase Are Associated With Pupal Melanization During Larval-Pupal Transformation in Antheraea pernyi.

In insects, melanism plays important roles in defense, immunoreactions, and body color. The underlying molecular mechanisms of melanism in different insects are diverse and remain elusive. In contrast to another silkworm, Bombyx mori, the Chinese oak silkworm, Antheraea pernyi, produces melanic pupae under natural environmental conditions. DOPA and dopamine synthesis are crucial for melanin formation. Disruption of these processes reportedly influences body colors in many insects. Most research focuses on newly emerged pupae, and the larval process preceding pupation remains unknown. Due to the large size and long pupation period in A. pernyi, the entire process was studied at least every 12 h. The expression patterns of tyrosine hydroxylase (TH) and DOPA decarboxylase (DDC), which are involved in DOPA and dopamine synthesis in the epidermis, were evaluated during larval–pupal metamorphosis. We also performed RNA interference (RNAi) and used enzyme inhibitors to examine morphological changes. The amino acid sequences of TH and DDC share 90.91% and 86.64% identity with those of B. mori. TH and DDC expression was upregulated during the 48–72 h period prior to pupal emergence, especially at 60 h. RNAi of TH and DDC induced partial melanism in some pupae. The inhibitors 3-iodo-tyrosine (3-IT) and L-α-methyl-DOPA (L-DOPA) influenced pupal melanization. Different concentrations of inhibitors led to pupal deformity and even mortality. Four different monoamines, only DOPA and Dopamine synthezed from Tyrosine will be influenced by TH and DDC inhibitor. These results indicate that TH and DDC are key genes associated with pupal melanization during larval–pupal transformation in A. pernyi. Overall, our results suggest that TH and DDC expression alterations in a particular stage can affect body color, setting the molecular basis for artificial control of pupal melanization.

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.

Genetically engineered pH-responsive silk sericin nanospheres with efficient therapeutic effect on ulcerative colitis

Ulcerative colitis (UC) is one type of inflammatory bowel disease (IBD) and lactoferrin (LF) is a promising protein drug to treat UC. However, targeted LF delivery to optimize bioavailability, targeting and effectiveness remains a challenge. Here, we report an effective strategy to fabricate silk sericin nanospheres systems for the delivery of recombinant human lactoferrin (SS-NS-rhLF). The system is based on the use of optimized transgenic silkworms to generate genetically engineered silk fibers (rhLF-silks). The rhLF silks were used for fabricating SS-NS-rhLF by ethanol precipitation. The SS-NS-rhLF were stable with a spherical morphology with an average diameter of 123 nm. The negatively charged sericins in a pH ≥ 5.5 environment achieved specific targeting of the SS-NS-rhLF to positively charged colonic sites. The SS-NS-rhLF achieved efficient uptake by cells in the inflamed colon of mice when compared to free lactoferrin in solution (SOL-rhLF). Furthermore, oral administration of the SS-NS-rhLF with low dose of rhLF significantly relived symptoms of UC in mice and achieved comparable therapeutic effect to the high dose of SOL-rhLF by supporting the reformation of cell structure and length of colon tissue, reducing the release of inflammatory factors, inhibiting the activation of the NF-κB inflammatory pathway, and maintaining a stable intestinal microbial population in mice. These results showed that the SS-NS-rhLF is a promising system for colitis treatment. Statement of significanceTargeting and effective delivery of multiple biological functional protein human lactoferrin (rhLF) is a promising strategy to treat ulcerative colitis in the clinic. Here, rhLF-transgenic silk cocoons were used to fabricate a rhLF-sericin nanosphere delivery system (SS-NS-rhLF). The fabricated SS-NS-rhLF showed identical spherical morphology, stable structure, sustainable rhLF release, efficient cell uptake and negative charge in an environment of pH above 5.5, thus realized the specific targeting to the positively charged colonic sites to treat UC mice through oral administration. The therapeutic effect of SS-NS-rhLF with a low rhLF dose in the UC mice was comparable to the high dose of free rhLF treatment in solution form, suggesting that the SS-NS-rhLF is a promising system for colitis treatment.

Dual-functional bioactive silk sericin for osteoblast responses and osteomyelitis treatment.

Sericin, a natural protein from silk cocoon, has been reported for various biological properties in the biomaterials field. Modified forms of sericin have been studied for bone tissue engineering, while its unmodified form has been scarcely reported. Therefore, the purpose of this study was to evaluate physical and biological properties of unmodified sericin for potential use in bone surgery. Sericin was extracted from silk cocoons using a chemical-free boiling method. Sericin extract showed distinct bands with molecular weight ranging from 25 to 42 kDa including smear bands. Fourier transform infrared spectra presented characteristic peaks of amide I, II, and III, confirming the chemical composition of sericin. Based on biological activity, sericin extract at a concentration of 40 μg/mL increased the proliferation of osteoblast cells up to 135%, compared with the untreated control. Moreover, increase in antibacterial activity against Staphylococcus aureus, both clinical isolates and the reference strain ATCC 29213, was demonstrated for sericin extract with normal saline, while no antibacterial activity was observed for sericin with broth. It was found that sericin with normal saline showed higher zeta potential than sericin without normal saline, indicating higher system stability. This was confirmed by the average particle size of sericin extract with NaCl (3,249.3±226.1 nm) showing approximately 10 times smaller than sericin solution (29,015.9 ± 8,085.6 nm). Furthermore, sericin extract at the minimal inhibitory concentration significantly reduced the biofilm formation of S. aureus up to 95%. The study indicates biological activities of sericin, which could be applied as a dual-functional bioactive material to support bone regeneration and treat bone infections.

Improved Maturation Rate of Bovine Oocytes Following Sericin Supplementation in Collection and Maturation Media

Sericin is a water-soluble protein produced by silk cocoons and known to have antioxidant activity. This study is aimed to analyze the nuclear maturation and the quality of bovine oocytes in the collection and in vitro maturation (IVM) medium supplemented with sericin. Bovine oocytes were collected using a collection medium supplemented with sericin in 0 (control) concentrations, 0.1%, 0.5%, and 1%. Selected oocytes were then matured for 24 h at 38.5 o C in 5% CO₂ and evaluated for nuclear maturation. In the subsequent experiment, oocytes were collected and matured with or without 0.1% sericin at 38.5 o C in 5% CO 2 . Matured oocytes were counterstained with terminal deoxynucleotidyl transferase nick-end labeling (TUNEL) and Hoechst 33342. Matured oocytes were characterized by oocytes that reached the MII stage. The results showed that supplementation of 0.1% sericin in the collection medium increased the number of oocytes reaching the metaphase II (MII) stage compared to the control group (p<0.05). In the next experiment, sericin 0.1% in the collection and in vitro maturation media increased (p<0.05) the percentage of oocytes reaching the MII stage compared to control without sericin supplementation. Furthermore, the number of fragmented DNA in the oocytes showed no differences in all groups. It can be concluded that supplementation of 0.1% sericin in the collection and in vitro maturation media improved the nuclear status without affecting DNA fragmentation.

Dissecting the Isoform-Specific Roles of FTZ-F1 in the Larval-Larval and Larval-Pupal Ecdyses in Henosepilachna vigintioctopunctata.

Simple SummaryFushi Tarazu Factor-1 (FTZ-F1) plays a crucial regulatory role in molting in insects. It is hypothesized that, by alternative transcription start and splicing, the FTZ-F1 gene generates two isomers (α- and βFTZ-F1) that exert isoform-specific roles in non-Drosophilid insects. In the present paper, we first unveiled that the same post-transcriptional processing in FTZ-F1 occurred in coleopterans, lepidopterans, dipterans and hymenopterans. We then found that αFTZ-F1 and βFTZ-F1 were actively transcribed throughout the development, from embryo to adult, in Henosepilachna vigintioctopunctata. Moreover, by RNA interference, we confirmed that both FTZ-F1 isoforms act as regulators in larval–larval molting and βFTZ-F1 is involved in the regulation of the larval–pupal transition.Fushi Tarazu Factor 1 (FTZ-F1), a member of the nuclear receptor superfamily, is the downstream factor of 20-hydroxyecdysone signaling. In Drosophila melanogaster, alternative transcription start and splicing in the FTZ-F1 gene generate αFTZ-F1 and βFTZ-F1 isoforms, which are vital for pair-rule segmentation in early embryogenesis and post-embryonic development, respectively. However, whether the same mRNA isoforms are present and exert the conservative roles remains to be clarified in other insects. In the present paper, we first mined the genomic data of representative insect species and unveiled that the same post-transcriptional processing in FTZ-F1 occurred in coleopterans, lepidopterans, dipterans and hymenopterans. Our expression data in Henosepilachna vigintioctopunctata, a serious polyphagous defoliator damaging a wide range of crops in Solanaceae and Cucurbitaceae, showed that both αFTZ-F1 and βFTZ-F1 were actively transcribed throughout the development, from embryo to adult. The RNA interference-aided knockdown of both isoforms completely arrested larval ecdysis from the third to the fourth instar, in contrast to the depletion of either isoform. In contrast, silencing βFTZ-F1, rather than αFTZ-F1, severely impaired the larval–pupal transformation. We accordingly propose that both FTZ-F1 isoforms are essential but mutually interchangeable for larval–larval molting, while βFTZ-F1 is necessary for the larval–pupal transition and sufficient to exert the role of both FTZ-F1s during larval–pupal metamorphosis in H. vigintioctopunctata.

Optical and Structural Properties of Insoluble and Flexible Biodegradable Regenerated Silk Films for Optically Transparent Hydrophilic Coating of Medical Devices

AbstractMany medical equipment, such as tubes, lenses, and disposable plastic slides, require improved wettability to perform properly with physiological fluids and tissues. The authors proposes the regeneration of silk cocoons into insoluble and flexible regenerated silk fibroin (SF) films allowed for the development of novel materials with distinct and convincing characteristics. The SF films with glycerol modifications are created using a casting/solvent evaporation technique to provide a flexible and optically transparent hydrophilic coating. Fourier‐transformed infrared spectroscopy and wide‐angle X‐ray diffraction reveal a structural shift in glycerol‐induced SF films, where the random coil and helical structure content reduce while the β‐sheet structure increases significantly. All of the proposed SF films have an outstanding transmission of approximately 90% in the visible range and a UV‐shield characteristic. Tensile tests reveal that glycerol‐plasticized SF films are soft and extremely flexible, with a high Young's modulus and moderate tensile strength. The adhesion strength of the SF films is assessed as 5B at 10–20% wt of glycerol, suggesting outstanding adhesion strength on the silanized glass surface. At 30% w/w glycerol, the SF film has the greatest swelling ratio of 95.3 ± 0.5% and the lowest water contact angle of 23.2°.

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.

Impact of antibiotic administration on the growth and development of silkworm Bombyx mori L.

The present investigation was carried out to assess the rearing performance and total haemocyte count in silkworm Bombyx mori L. on antibiotic supplemented feed at various concentrations. The study was conducted on the silkworm breed APS-45.The worms were reared upto 3rd moult by feeding on mulberry leaves without any treatment. After 3rd moult, three replications were maintained for each treatment and each treatment received different concentration of antibiotics. For each antibiotic three concentrations (0.05%, 0.10% and 0.15%) were prepared and sprayed on the mulberry leaves, a separate batch was also maintained where only distilled water was sprayed and that served as a control. Among the three antibiotics evaluated ceftiofur sodium showed best results followed by oxytetracycline and enroflaxcin which also showed better results in all the parameters and it was found that improved results were obtained with an increase in concentration. The cocoon yield was statistically significant in all the treatments. However, the highest cocoon yield by weight was obtained in ceftiofur sodium. Higher cocoon weight recorded in these antibiotic treated batches indicated a clear difference in their nutrient utilization efficiency. Present investigation reflected that antibiotics have the potential to be used for enhancing the cocoon and raw silk production.

Toughening Wet-Spun Silk Fibers by Silk Nanofiber Templating.

Regenerated silk fibers typically fall short of silkworm cocoon fibers in mechanical properties due to reduced fiber crystal structure and alignment. One approach to address this has been to employ inorganic materials as reinforcing agents. The present study avoids the need for synthetic additives, demonstrating the first use of exfoliated silk nanofibers to control silk solution crystallization, resulting in all-silk pseudocomposite fibers with remarkable mechanical properties. Incorporating only 0.06wt% silk nanofibers led to a ≈44% increase in tensile strength (over 600MPa) and ≈33% increase in toughness (over 200kJkg-1 ) compared with fibers without silk nanofibers. These remarkable properties can be attributed to nanofiber crystal seeding in conjunction with fiber draw. The crystallinity nearly doubled from ≈17% for fiber spun from pure silk solution to ≈30% for the silk nanofiber reinforced sample. The latter fiber also shows a high degree of crystal orientation with a Herman's orientation factor of 0.93, a value which approaches that of natural degummed B. mori silk cocoon fiber (0.96). This study provides a strong foundation to guide the development of simple, eco-friendly methods to spin regenerated silk with excellent properties and a hierarchical structure that mimics natural silk.