Non-bioengineered silk gland fibroin protein: characterization and evaluation of matrices for potential tissue engineering applications

The possibility of using wild non-mulberry silk protein as a biopolymer remains unexplored compared to domesticated mulberry silk protein. One of the main reasons for this was for not having any suitable method of extraction of silk protein fibroin from cocoons and silk glands. In this study non-bioengineered non-mulberry silk gland fibroin protein from tropical tasar silkworm Antheraea mylitta, is regenerated and characterized using 1% (w/v) sodium dodecyl sulfate (SDS). The new technique is important and unique because it uses a mild surfactant for fibroin dissolution and is advantageous over other previous reported techniques using chaotropic salts. Fabricated fibroin films are smooth as confirmed by atomic force microscopy. Circular dichroism spectrometry along with Fourier transformed infrared spectroscopy and X-ray diffraction reveal random coil/alpha-helix conformations in regenerated fibroin which transform to beta-sheets, resulting in crystalline structure and protein insolubility through ethanol treatment. Differential scanning calorimetry shows an increase in glass transition (Tg) temperature and enhanced degradation temperature on alcohol treatment. Enhanced cell attachment and viability of AH927 feline fibroblasts were observed on fibroin matrices. Higher mechanical strength along with controllable water stability of regenerated gland fibroin films make non-mulberry Indian tropical tasar silk gland fibroin protein a promising biomaterial for tissue engineering applications.