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Silk nanofibers have been produced and examined in recent years for a range of advanced biomedical and biotechnological applications. Their fabrication involves the canonical approach of dissolving...

We characterised fibres and papers of microfibrillated silk from Bombyx mori produced by mechanical and enzymatic process. Milling increased the specific surface area of fibres from 1.5 to 8.5 m2/g and that enzymatic pre-treatment increased it further to 16.5 m2/g. These fibrils produced a uniform, significantly strong (tenacity 55 Nm/g) and stiff (Young's modulus > 2 GPa) papers. Enzymatic pre-treatment did not reduce molecular weight and tensile strength of papers but significantly improved fibrillation. Silk remained highly crystalline throughout the fibrillation process. Protease biodegradation was more rapid after fibrillation. Biodegradation was impacted by structural change due to enzymatic pre-treatment during the fibrillation. Biodegraded silk had much higher thermal degradation temperature. The unique combination of high strength, slow yet predicable degradation and controllable wicking properties make the materials ideally suited to biomedical and healthcare applications.

Silk fiber is formed by an assembly of fibrils. The fibrils can be isolated by a top-down mechanical process called microfibrillation and the fibrils are known as microfibrillated silk (MFS). The process involves chopping, milling, enzyme treatment and high-pressure homogenization. The milling is an important manufacturing step and to optimize the milling step, a response surface methodology was used in this work where the influence of fiber content in milled suspension, milling time and alkaline concentration were investigated. Output responses for the optimization were diameter distribution of fibrils, size and percentage of different diameter fractions, and the aspect ratio. The main and interaction effects of the milling parameters on these responses were statistically analysed. Milling time was the most significant factor for producing finer fibrils while the fiber content in milling had the maximum impact in reducing the number of large fibrils. Milling time had a positive correlation with the aspect ratio. The optimized milling resulted in MFS with an average diameter of 55.35 nm and 90% of MFS less than 100 nm based on high-magnification SEM image analysis. The aspect ratio of the MFS was 137. The MFS suspension was stable over the pH range 3–11.

The aim of the study was to evaluate the performance of dyes extracted from mango leaves in silk dyeing. Extraction medium was optimized by extracting dyes from fixed quantity of crushed leaves under pH values from 3 to 12. The maximum relative color strength of the extracted dye liquor was found to be at pH 10. The optimum dye extraction conditions i.e., the temperature, time, and material-to-liquor ratio were found to be 98 °C, 60 min, and 1:10, respectively. Dyeing was carried out with the optimized dye extract on mordanted and unmordanted silk fabrics. The dyed materials were evaluated by measuring the color yield and fastness properties. It was concluded that the color values were found to be influenced by the addition of mordants, consequently different fashion hues were obtained from the same dye extract using different mordants. It can also be said that mango leaves have good potentiality for dyeing of silk fabric.