2, Rural Development Administration, Wanju, , Korea (the Republic of)
3, Purdue University, West Lafayette, Indiana, United States
Numerous studies have been reported on integration of plasmonic nanomaterials and nanostructures into wearable and flexible devices. For their widespread and practical utilization, it is beneficial to realize two crucial features: From a wearable technology standpoint, it is critical to realize large-area/flexible/biocompatible clothing with specific functionalities (e.g., biosensing, communication, and hazard protection). From a manufacturing standpoint, it is important to eco-friendly produce nanomaterials on a large scale. In this respect, there is always a combined need for both flexible/scalable/biosafe functionalities and green manufacturing/production for plasmonic nanomaterials and nanostructures. In this presentation, we report that native silk produced by silkworms appears to be an alternative plasmonic photonic platform for hybridizing metal nanoparticles and natural biomaterials via green chemistry. This approach is inspired from ‘silk weighting’ which is the old method in the 19th century for increasing the weight of raw silk for high price. Silk has a strong affinity for several metallic salts, which results in the formation of metal nanoparticles with finite sizes inside the interfibrillar nanostructures of silk. Moreover, this process can be enhanced by plant-derived polyphenolic chemistry. The reported wholly integrated plasmonic native fibers are distinct from other nanomaterial hybridizations that are focused on attaching metal nanoparticles on the fiber surface. We further demonstrate plasmon-enhanced photoluminescence of far-red fluorescent protein (mKate2) in silk produced by genetically engineered silkworms (i.e., silkworm transgenesis). Our results provide the groundwork for exploiting natural silk as a photonic nanomaterial hybridization platform to implement embedded functionalities in a fiber geometry, which can be constructed into large-area fabrics. Additionally, this insect factory along with green chemistry could potentially open an alternative nanomanufacturing strategy in an eco-friendly, scalable, and sustainable manner, minimizing the use of complex nanofabrication methods.