In addition,
the gas (i.e. oxygen, carbon dioxide, water vapour) diffusion properties of silk materials present in the cocoon,
which allows the Bombyx mori to survive through the pupal phase of its lifecycle, can be tailored in regenerated
protein by regulating silk fibroin polymorphism. This, for example, has ensured the correct gas exchange
in silk fibroin materials engineered for corneal grafting28–30. In particular, silk fibroin with modular degrees of
beta-sheet content can be obtained by regulating the time (minutes to hour range) and temperature (4–95 °C) to
which the protein gets exposed to water vapour or edible polar solvents (i.e. ethanol