The feasibility of degumming Persian silk with alcalase, savinase, and mixtures of these enzymes with different alcalase/savinase weight ratios (0/1, 0.25/ 0.75, 0.5/0.5, 0.75/0.25, and 1/0 g/L) was investigated. The results were compared with those of soap degumming, which is a common silk degumming process. The effectiveness of parameters such as the treatment time, concentration of enzymes, and liquid ratio on degumming was studied. The enzymatic degumming process was performed at 558C with an operation time of approximately 30 min, whereas the soap degumming process was carried out around the boiling point in 120 min. The evaluation of the data was carried out through the measurement of the weight loss, strength, and elongation of the samples. The optimum amount of sericin removed was 21.52 wt % for alcalase in 30 min, 20.08 wt % for savinase in 60 min, and 22.58 wt % for soap in 120 min. Also, the enzymatic treatment improved properties of the silk yarn such as the strength (33.76 cN/tex for alcalase and 32.03 cN/tex for savinase) and elongation (20.08% for alcalase and 18.42% for savinase). The obtained values were better than the strength (29.90 cN/tex) and elongation (18.59%) from the soap degumming method. Through the use of an enzyme mixture (0.5/0.5 g/L), good weight loss (22.43%), strength (33.22 cN/tex), and elongation (17.74%) were achieved in 30 min. Scanning electron micrographs confirmed and supported the observed data.

Two small series of cationic gemini surfactants with dodecyl tails have been synthesized and evaluated with respect to self-assembly in bulk water and at different solid surfaces. The first series contained a flexible alkane spacer and is denoted 12-n-12, with n = 2, 4, and 6. The second series had a phenylene group connected to the quaternary nitrogens in either the meta or para position and the surfactants are referred to as 12-m-Φ-12 and 12-p-Φ-12, respectively. The phenylene group is a rigid linker unit. The critical micelle concentration (cmc) was determined both by tensiometry and by conductometry, and the packing density of the surfactants at the air-water interface was calculated from the Gibbs equation. The cmc values for the geminis with a rigid spacer, 12-m-Φ-12 and 12-p-Φ-12, were of the same order of magnitude as for 12-4-12, which is the flexible surfactant that most closely matches the phenylene-based surfactants with respect to hydrophobicity, measured as log P, and distance between the positively charged nitrogen atoms. The adsorption of flexible and rigid surfactants was investigated on gold, silicon dioxide (silica), gold made hydrophobic by the self-assembly of hexadecanethiol, and gold made hydrophilic by the self-assembly of 16-hydroxyhexadecanethiol. On all of the surfaces, there was a reverse relationship between the adsorbed amount at the cmc and the length of the spacer (i.e., 12-2-12 gave the highest and 12-6-12 gave the lowest amount of adsorbed material). The adsorption pattern was similar for all of the surfactants when recorded at 25 °C. Thus, one can conclude that a rigid spacer does not render the self-assembly of a gemini surfactant difficult, neither in bulk water nor at solid surfaces. However, on one of the surfaces-untreated gold-the adsorbed amount of the geminis with a rigid spacer at 40 °C was approximately twice the values obtained at 25 °C. This is interpreted as the formation of an interdigitated bilayer at 25 °C and a regular bilayer without interpenetration of the alkyl chains at 40 °C.

A water-soluble chitosan derivative namely, N-(2-hydroxy) propyl-3-trimethylammonium chitosan chloride (HTCC) was synthesized by the reaction of chitosan with glycidyltrimethyl ammonium chloride in a neutral aqueous condition and solution blended with polyacrylonitrile (PAN) in an organic solvent. Polymeric films were made by casting, and they were dyed with an acid dye, a basic dye, and mixture of them. Results obtained from differential scanning calorimetry, scanning electron microscopy, and dyeing show that these polymers are immiscible even at low percentage of HTCC (lower than 20%). However, at higher ratio, the phase separation takes place.Fibers obtained from this blend system by wet-spinning technique show a good mechanical properties and increasing the amount of HTCC causes an increment in the mechanical strength of the fibers up to 20% of HTCC and beyond that due to phase separation mechanical strength reduces. Blending PAN with HTCC improves the dyeing behavior of the films and fibers.

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An acid-free water-born chitosan derivative/montmorillonite has been successfully synthesized. A natural-based biopolymer, N-(2-hydroxy) propyl-3-trimethyl ammonium chitosan chloride, was synthesized, and its structure confirmed by Fourier transform infrared microscopy and conductometric titration. It was applied to the cationic ion-exchange reaction of montmorillonite. Then, the synthesized materials were used to produce water-born composite scaffolds for tissue engineering applications and formed an ultra-fine bead-free multicomponent nanofibrous scaffold. The scaffold was subjected to in vitro and in vivo investigations. The effects of both acidic and neutral reaction media on the efficiency of the cationic ion-exchange reaction of montmorillonite were investigated. A mechanism has been suggested for the more efficient cationic ion-exchange reaction achieved in the absence of the acid. In in vitro studies, the modified montmorillonite showed synergistic biocompatibility and cell growth with enhanced bioactivity compared to unmodified clay and even chitosan and the chitosan derivative. Scanning electron microscopy showed ultra-fine bead-free nanocomposite nanofibers. Improved biocompatibility, cell attachment, and cell growth were observed for the nanofibrous scaffolds compared to the individual components. In vivo experiments showed complete restoration of a critical-sized full-thickness wound without infection in 21 d. The technique provides a guideline to achieve chitosan nanofibrous morphology for multifunctional biomedical applications.