Insoluble fibroin films were prepared without methanol treatment. A 15 wt % fibroin solution was obtained through concentration, and then, the insoluble film was achieved by the adjustment of the drying temperature and rate. These films were examined through Fourier transform infrared–attenuated total reflection, X-ray diffraction, and scanning electron microscopy to determine the structure of the silk fibroin. The physical and mechanical properties were investigated to discover the feasibility of using these films as biomedical materials. When fibroin films were dried above 60℃, abundant -sheet crystals existed in the fibroin films, and many globule-containing micelles aggregated and interacted with each other, which resulted in excellent mechanical properties of the regenerated fibroin films in the wet state. Interestingly, the amide III band of the random coil structure in the fibroin films dried at 70 and 80℃ was shifted to a lower frequency, 1228cm 1, which meant that a partly orientated structure formed. This may have also affected the mechanical properties of the fibroin films. The tensile strength and breaking elongation of the films dried at 70℃ were 29.8MPa and 59.6%, which is distinctly superior to fibroin films treated with methanol. If the drying temperature was raised to 60℃, the stability of the films in water was also excellent.

Intercalation of ZnO quantum dots into two-dimensional (2D) laminated sodium lauryl sulfonate films in a colloidal solution was demonstrated. Without any substrates, hybrid films composed of a dispersed ZnO dots layer and organic films exhibit a high stability and regular 2D superlattice stacking after removal of cosurfactant molecules and water. The 2D superlattice films were characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). UV-visible absorption and photoluminescence spectra were used to investigate the growth of ZnO QDs between organic films and study their collective optical characteristics. 2005 Elsevier Inc. All rights reserved.

Semiconductor ZnS nanotubes, with outer diameters in the range of 37-52nm and lengths up to 3 microns, have been successfully synthesized from solutions containing a nonionic surfactant, Triton X-100 (t-octyl-(OCH2CH2)xOH, x=9,10). The as-synthesized nanotubes have been characterized by X-ray diffraction (XRD) and transmission electron microscope (TEM). The growth mechanism of nanotubes has also been discussed.

Blending degummed fibroin (DF) or insoluble fibroin microspheres with concentrated fibroin solution, the insoluble films were obtained through drying the solution at 40-45℃. The conformation of silk fibroin films was analyzed by infrared spectrum and X-ray diffractometry. The results demonstrated that β-sheet conformation increased rapidly when the degummed silk or insoluble microspheres blended with fibroin, while the pure SF membrane was mainly composed of α/random coil conformation when the other conditions kept same. This suggested that fibroin microspheres and degummed fibroin could induce the formation of β-sheet crystal and the insoluble films, without methanol after-treatment, could be obtained at approximately room temperature. Although the fibroin films blending with DF had many protuberances, the films containing fibroin microspheres had the smooth surface and could be used effectively in biotechnological materials and biomedical application.

Fe0.32Ni0.68 alloy nanotubes have been successfully synthesized by electrochemical deposition using a polycarbonate membrane template. The transmission electron microscope and scanning electron microscope observations reveal that the nanotubes have a conical morphology with two ends stuffed and a hollow structure. The length and diameter of the nanotubes are 7-8 μm and 200 nm, respectively. The aspect ratio (length to diameter) is as large as 40. Magnetic measurements show that the coercivities of the nanotubes for an applied parallel and perpendicular field are about 21 and 55 Oe, respectively. The hysteresis loops indicate that the nanotubes were more easily magnetized in applied parallel field than in applied perpendicular field. The mechanism of nucleation and growth of these nanotubes is also discussed.