Researchers at the Wyss Institute for Biologically Inspired Engineering have invented a biomimetic material that mimics the material that forms insect cuticle. The clear film is biocompatible, biodegradable, and micromoldable, and is twice as strong as nylon or polylactic acid (PLA), while exhibiting the strength of an aluminum alloy at half its weight. The material could be used to replace plastic materials used in bags, bottles, diapers, packing materials and more. It can also be used for medical applications because of its biocompatibility and biodegradability.Researchers have in the past attempted to engineer materials resembling insect cuticle, using combinations of chitin and proteins. These attempts have been unsuccessful in creating materials with the desired properties. Now, instead of merely combining materials, the Harvard researchers attempted to re-create the actual structure of insect cuticle. Insect cuticle is a composite material consisting of layers of protein and chitin–a polysaccharide polymer and the second most abundant polymer on earth–organized in a laminar, plywood-like structure. According to a Harvard news release, “Mechanical and chemical interactions between these materials provide the cuticle with its unique mechanical and chemical properties. By studying these complex interactions and recreating this unique chemistry and laminar design in the lab, [Wyss researchers] Fernandez and Ingber were able to engineer a thin, clear film that has the same composition and structure as insect cuticle.”The name “Shrilk” reflects the sources for materials to create the film. Chitosan is isolated from shrimp shells, which are a waste product of the seafood industry. The protein, fibroin, used in the design comes from silk. While the materials are harvested, the design itself is biomimetic.
According to the Harvard news release, “Natural insect cuticle, such as that found in the rigid exoskeleton of a housefly or grasshopper, is uniquely suited to the challenge of providing protection without adding weight or bulk. As such, it can deflect external chemical and physical strains without damaging the insect’s internal components, while providing structure for the insect’s muscles and wings. It is so light that it doesn’t inhibit flight and so thin that it allows flexibility. Also remarkable is its ability to vary its properties, from rigid along the insect’s body segments and wings to elastic along its limb joints.”Insect cuticle is a composite material consisting of layers of chitin, a polysaccharide polymer, and protein organized in a laminar, plywood-like structure. Mechanical and chemical interactions between these materials provide the cuticle with its unique mechanical and chemical properties.”Edit Summary