Chemical, structural and thermal properties of Gonometa postica silk fibroin, a potential biomaterial.

In the present study, chemical, structural and thermal properties of fibroin from Gonometa postica, a wild silkmoth species were investigated. Silk from Gonometa rufobrunnea and Bombyx mori species were included in this study for comparison. The results indicated that G. postica and G. rufobrunnea silk exhibited similar properties whereas distinct differences were observed with B. mori silk. Amino acid analysis showed that glycine, alanine and serine accounted for more than 70% of the total amino acid content in all species. The amount of polar amino acids in Gonometa fibroin was significantly higher than for B. mori fibroin suggesting increased chemical reactivity of the former. The abundance of basic amino acids in Gonometa fibroin makes it a promising biomaterial in cell and tissue culture. Structural analysis revealed a unique β-sheet structure of Gonometa fibroin which is comprised of both poly-alanine and poly-glycine-alanine sequences. The maximum decomposition temperatures for Gonometa and B. mori fibroin were 350°C and 320°C respectively. The influence of amino acid composition on structural and thermal properties of the silks is also discussed.