Introduction
The silkworm, Bombyx mori, secretes two proteins, fibroin and
sericin. Fibroin (SF) is the major protein and its content is about
75% of the total silk protein. It has been used as a textile but new
applications can be found in biomedical fields as well [1,2]. On the
other hand, sericin (SS) is the minor protein which envelops two
strands of SF and it constitutes about 25% of the total silk protein. In
order to get the unique luster and touch in silk textiles or to purify
SF for biomedical applications, SS should be removed by a degumming
process. Recently, there is much interest in natural polymers
not only due to the environmental concerns but also due to the
exhaustion of petroleum sources in the future. Considering that
the annual production of silk cocoons is about 600,000 tons, nearly
150,000 tons of SS are abandoned every year, which could be a good
natural resource if recycled. There are continuous efforts to reuse
SS in various fields [3–6] but still their application is limited due to
some unsuitable properties.