The silk produced by larvae of the silkworm, Bombyx mori, is a long thread composed of shorter interlocking strands of silk protein. Silk thread can be disassociated into its protein units, silk nanofibrils. These nanofibrils can be dissolved in solution and when appropriately filtered, will form a membrane of interlocking silk nanofibrils.
The membranes are useful for filtration applications They are free standing, do not dissolve in water or solvent and can be cut to a desired shape. The membranes contain nanopores from 4 to 20 nm. The thickness of the membrane can be varied by altering the conditions used to produce the membrane. Increasing the membrane thickness from 40 nm to 120 nm decreases the pore size. The membranes have water permeabilities similar to other filtration materials. Insect biomaterials such as silk are increasingly important in nanoscale materials applications.
Shengjie Ling, Kai Jin, David L. Kaplan, and Markus J. Bueller. Ultrathin Free-Standing Bombyx mori Silk Nanofibril Membranes. Nano Letters 2016 16 (6), 3795-3800