The domesticated silkworm Bombyx mori silk fibroin consist of two proteins: a light chain (∼25 kDa) and heavy chain (∼370 kDa) which are present in a 1:1 ratio and linked by a single disulfide bond [14]. The molecular structure of silks consists of large regions or domains of hydrophobic amino acids, segregated by relatively short and more hydrophilic regions.
For drug delivery, especially protein drugs, silk materials exhibit high encapsulation efficiency and controllable drug release kinetics due to the control of crystalline beta-sheet formation