Over the past few decades, Bombyx mori silk fibroin has become a ubiquitous material for applications ranging from biomedical devices to optics, electronics, and sensing, while also showing potential in the food supply chain and being re-engineered as a functional material for architecture and design-related applications. Its widespread use derives from its unique properties, including biocompatibility, edibility, optical transparency, stabilization of labile compounds, and the ability to controllably change conformation and degrade in a programmed way. This review discusses recent and pivotal silk-based devices in which the presence of silk brings added value in terms of functionality, as demonstrated in a broad variety of fields. First, it gives an overview of silk's natural structure and main properties in terms of cross-linking, biocompatibility, and biodegradability to provide the reader with the necessary toolbox to fully make use of silk's multifaceted properties. Then, multifunctional silk-based devices are discussed highlighting the advantage of using silk over more traditional materials. Representative devices from both established and emerging applications for silk are examined. Finally, a roadmap for the next generation of silk-based devices is laid out.

In this study, a new edible coating material with enhanced mechanical and gas barrier properties was studied by coupling silk fibroin (SF) with poly(vinyl alcohol) (PVOH). SF and PVOH water suspensions were mixed at different ratios to form multilayered membranes that, after a phase separation, assembled on the surface of fresh-cut produce upon dip coating. The effects of the mixing ratio on transparency, mechanical properties, water vapor, and oxygen permeability of the films were investigated. Higher PVOH fractions corresponded to an increased ductility (increased elongation at break and decreased Young's modulus), which is essential for a food packaging material. A coating with SF:PVOH weight ratio 1:1 presented the minimum water vapor permeability and was selected to perform perishable food preservation studies. Weight loss and color changes of coated fresh-cut apples over 14 days of storage at 4 °C were significantly lower than those of uncoated controls. The addition of ascorbic acid to the coating material was also investigated to obtain an active food coating with oxygen scavenging properties. The obtained results demonstrated the ability of SF:PVOH blends to assemble into bilayered edible coatings that extend the shelf life of fresh-cut produce.

No abstract