Silk's crystalline structure makes it one of nature's toughest materials, while fibroin can protect other materials while being fully biodegradable.
Using a water-based fabrication method based on protein self-assembly, engineers from Tufts University have created a new material out of silk protein that they say can be pre-programmed with biological, chemical or optical functions, such as mechanical components that change colour with strain, deliver drugs or respond to light.
In a paper published in Proceedings of the National Academy of Sciences (PNAS), the researchers described how they were able to create three-dimensional bulk materials out of silk fibroin—the protein that gives silk its durability—which they manipulated with water-soluble molecules to create multiple solid forms, from the nano- to the micro-scale, that have embedded, pre-designed functions.
Figure 1: A silk fibroin screw can be heated to 160°C when exposed to infrared light. (Source: Silk Lab)
For example, the researchers created 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.
Although more research is needed, additional applications could include new mechanical components for orthopaedics that can be embedded with growth factors or enzymes, a surgical screw that changes colour as it reaches its torque limits, 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 a remarkable ability to protect other materials while being fully biocompatible and biodegradable.
“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,” said senior and corresponding study author Fiorenzo G. Omenetto, Ph.D. Omenetto is the Frank C. Doble Professor in the Department of Biomedical Engineering at Tufts University’s School of Engineering and also has an appointment in the Department of Physics in the School of Arts and Sciences.