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Engineers at Tufts University in Massachusetts have developed a material made from silk protein that can be preprogrammed with biological, chemical or optical functions. It could be used to develop components that change colour with strain, deliver drugs or respond to light.
Using a water-based fabrication method based on protein self-assembly, the researchers generated 3D bulk materials out of fibroin, the protein that gives silk its durability. The bulk materials were manipulated with water-soluble molecules to create multiple solid forms, from the nano to the micro-scale, that have embedded, predesigned functions.
The researchers used this technology to create a surgical pin that changes colour as it nears its mechanical limits and is about to fail, functional screws that can be heated on demand in response to infrared light, and a biocompatible component that enables the sustained release of bioactive agents, such as enzymes.
Fiorenzo Omenetto, senior study author, said: “The ability to embed functional elements in biopolymers, control their self-assembly, and modify their ultimate form creates significant opportunities for bio-inspired fabrication of high-performing multifunctional materials.”
The researchers said that, although further research is needed, additional applications of the technology could include mechanical components for orthopaedics that can be embedded with growth factors or enzymes, hardware such as nuts and bolts that sense and report on the environmental conditions of their surroundings, or household goods that can be remoulded or reshaped.
Silk’s unique crystalline structure makes it one of nature’s toughest materials. Fibroin, an insoluble protein found in silk, has the ability to protect other materials while being fully biocompatible and biodegradable.
The study was published in Proceedings of the National Academy of Sciences.