Silk remarkable mechanical properties, comparative biocompatibility, tunable degradation rates "in vitro" and "in vivo", the ease to load cellular growth factors (for example, BMP-2), and the ability to be processed into several other formats such as films, gels, particles, and scaffolds. Silks from "Bombyx mori", a kind of cultivated silkworm, are the most widely investigated silks. Silks derived from "Bombyx mori" are generally made of two parts: the silk fibroin fiber which contains a light chain of 25kDa and a heavy chain of 350kDa (or 390kDa) linked by a single disulfide bond and a glue-like protein, sericin, comprising 25 to 30
Bombyx mandarina true or mulberry silkmoths. The origin of the domesticated silkmoth is enigmatic. It has been suggested that it is the survivor of an extinct species which diverged from the ancestors of "Bombyx mandarina" millions of years ago. However, this is based on an untenable molecular clock hypothesis that assumes that wild and domestic silkmoths evolved equally fast after their lineages diverged. Rather, the effects of artificial selection have accelerated evolution in the domestic form to a point where it is hard to trace the origin of the numerous breeds of domestic silkworms even with the most modern molecular phylogeny methods.