Engineers at Tufts University have created programmable silk-based materials with embedded, pre-designed functions for biological, chemical, or optical capabilities.

As a result, end users will get functions in medical applications such as a surgical pin changing color when mechanical limits are stretched and is about to fail. It also works well for drugs by responding to biocompatible components.

Published in Proceedings of the National Academy of Sciences (PNAS) the paper explains how researchers had generated three-dimensional bulk materials out of silk fibroin in order to manipulate with water-soluble molecules for creating solid forms from nano to the micro-scale by embedded, pre-designed functions.

Intricate Experiments

Manipulating the bulk materials with water-soluble molecules, the Tuft engineers created multiple solid forms to a micro-scale level with pre-designed functions by embedding method.

Creation of a surgical pin capable of color change as it closes in on mechanical limits and heating of functional screws on demand with infrared light were demonstrable examples. Similar was a biocompatible component that was made to release bioactive agents like enzymes.

"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 study author Fiorenzo Omenetto, Professor at Tufts University in Massachusetts.

More research can lead to further applications including mechanical components for segments like orthopedics.

Leveraging Fibroin

Thanks to the unique crystalline structure, silk is one of the toughest materials. Many new applications of silk are emerging thanks to fibroin as an insoluble protein with the remarkable ability to protect other materials. The biocompatible and biodegradable properties are other highlights.

It may be understood that silk strand consists of filaments bound together by double strands of fibroin joined by silk sericin or silk gum.

Silk fibroin as a protein gives unique physical and chemical properties while Sericin acts as a second type of protein containing 18 amino acids. The primary role of Sericin is to envelop the fibroin.

Fibroin is attractive for several high-tech applications including multiple forms in which regenerated silk fibroin can be processed at high protein concentration and molecular weight.

The amino-acidic nature of silk fibroin lends diversity to side chains allowing macromolecules to be useful in drug delivery applications.

Silk fibroin's natural properties are used to the hilt in regenerated silk materials. By joining beta-sheet structures with inter- and intra-molecular hydrogen bonds that give high-flexibility to natural fiber, it further guarantees conformability in regenerated film formats.

Research is also progressing on the use of silk fibroin suspension as a coating material for perishable fruit preservation. Thanks to silk fibroin's flavorless and odorless nature, food coating and packaging applications may do well.

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