Mechanical properties of silk materials

Although the amino acid sequence as well as the secondary structure of fibroin differs from those of spidroin, the fibers spun from these proteins, that is, silkworm silk and spider silk have comparable mechanical properties. These may be attributed to the structural characteristics, both at the molecular and filament level. The superior mechanical properties of silk-based materials, such as films, coatings, scaffolds, and fibers produced using reconstituted or recombinant silk proteins, are determined by their condensed structures. 

In view of the various level of structural organization, it is worthwhile to draw a comparison between natural silk fibers (silkworm silk and spider silk) and man-made silk-based materials. 

The properties of natural silk are affected by numerous factors, such as nutrition, temperature, hydration state, extension rate, reeling speed (ICnight et al., 2000 Madsen et al., 1999 Riekel et al., 1999 Vollrath and ICnight, 1999 Vollrath et al., 2001), and spinning medium during the manufacture (Chen et al., 

Modified from literature (Engelberg and Kohn, 1991 Gosline et al., 1999 Hinman et al., 2000 Lewis, 2006 Pins et al., 1997 Vollrath and Porter, 2006 Vepari and Kaplan, 2007). 

Super-contraction, the chaperonage of the special structure of spidroin, is indeed an obstacle to the use of native spider dragline silk, especially in bioapplication (usually wet condition). Recently, it was found that the intrinsic properties of silk fibroin are much better than the data listed in Table 2. The inferior properties are generated by the spinning habit of 

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