Abstract: The physicochemical structures of silk from spider selenocosmia were characterized by means of IR, SEM and AFM. Based on the data of SEM and AFM, the diameters for the silk from spider selenocosmia were in the range of 100-500 nm, with the lower end of which this spider silk was considered as a kind of nanometer fibers. This silk from spider selenocosmia was much thinner than the silk from mulberry silkworm and the silk from spider nephila davipes, the diameters of which were 4 μm and 10～20 μm, respectively. Thus, the silk from spider selenocosmia could be considered as a natural nanometer fiber, which was rare in nature, especially in the form of a monofilament. It was shown from the results of IR spectra that the absorbance peaks of 1 644.73cm^-1, called as the amide Ⅰ structure, were correlated with the "random coil" and alpha-helix conformations in the amorphous part. The absorbance peaks of 1 517.44cm^-1, called as the amide Ⅱ structure, indicated B-sheet region plus a small amount of helical conformation existed. These molecular characterizations of silk from spider selenocosmia were similar to those of the silk from mulberry silkworm and the silk from spider Nephila davipes.

Key words: Silk from spider selenocosmia, Nanometer fiber, IR analysis, SEM, AFM