Silk: a versatile biomaterial for advanced optics and photonics

Silk-protein-based optical devices and multifunctional devices.

The growing developments of optical technologies in energy, environmental, information, and biomedical applications are creating a demand for optical materials and devices which are not only sustainable but also implantable and bioresorbable. Within this context, naturally-derived biomaterials, such as silk, cellulose, chitin, melanin, and DNA, provide a unique opportunity by being simultaneously "technological" (e.g., optically active, micro- and nanoscale processable), "structural" (e.g., rich surface chemistry, mechanical flexibility), "sustainable" (e.g., renewable, eco-friendly), and "biological" (e.g., biocompatible, biodegradable) making them ideally suited for applications at the interface between optical technologies and environment within human or around human.

Silks belong to a large family of structural proteins and are mainly synthesized by several arthropods, including silkworms and spiders. Among the different sources, domestic Bombyx mori silks come from abundant sources and have been the main focus for multi-field applications. Recent decades have witnessed the transition of applications of such an ancient material from traditional textile fields to advanced technical fields including optics and photonics, energy, electronics, and optoelectronics. More recently, great achievements have been made in the development of silk-based optical systems due to the advancements in multiscale manufacturing technologies.

In the article titled "Silk: a versatile biomaterial for advanced optics and photonics" published in Chinese Optics Letters, Vol. 18, Issue 8, 2020 (Yushu Wang, Meng Li, Yu Wang. Silk: a versatile biomaterial for advanced optics and photonics [Invited][J]. Chinese Optics Letters, 2020, 18(8):80004), the authors demonstrate the recent progress in advanced optical devices constructed from silk protein with a particular emphasis on the structural designs responsible for the final optical functionalities.

First, the justifications of using silk for optical applications are studied. The excellent balance of "structure-process-property-function" relationship of silk protein makes it distinct from other biopolymers. Then, the state-of-the-art silk-based optical devices are summarized in detail. The seamless match between silk protein and the advanced micro-/nanomanufacturing technologies, together with the versatility of silk protein, allows for the creation of silk optical devices with different forms, scales, and functions, including structural color materials, optical fibers and waveguides, diffractive optical elements, bio-lasers, plasmonic devices, metamaterials, and broadband reflection materials. Moreover, recent advances in silk-protein-based multifunctional optical devices are also demonstrated. The combination of silk self-assembly, top-down manufacturing techniques, and ease of functionalization enables the formation of silk optical devices with function diversity, such as the integration of different optical functions, the incorporation of optical function into structural function, and the coupling of optical function, information encoding, and thermal regulation. Finally, the challenges and directions for future devising silk-based optical materials and devices are discussed.

"Silk fibroin provides new opportunities towards the replacement of existing non-renewable optical platforms with environmentally friendly, biocompatible systems that match the high performance of their synthetic counterparts, while minimizing waste, environmental degradation, and energy-intensive input.", says the corresponding author Dr. Yu Wang, "silk will play a pivotal role in the future exploitation of sustainable, intelligent and adaptive, wearable/implantable, and multifunctional optical devices."

Although silk has shown great potential for applications in optics and photonics, further efforts still need to be devoted to developing silk-based optical materials and devices with an optimized "structure-property-function" relationship through sustainable, scalable, and facile manufacturing techniques.



光学技术在能源、环境、信息和生物医学领域中应用的不断发展正在对光学材料及器件提出全新的要求,材料需要可持续性而且具有可植入、可被生物吸收的能力。在此大背景下,天然衍生的生物材料(例如丝蛋白、纤维素、几丁质、黑色素以及DNA)体现出了独特的价值。该类材料同时具有 “技术的”(如光学活性、多尺度可加工性)、“结构的”(如丰富的表面化学、机械柔性)、“可持续的”(如可再生、环境友好)以及“生物的”(如生物相容性、可生物降解性)的特性,这使其非常适合应用于人体内/外环境之间的界面。


在Chinese Optics Letters 2020年第8期的封面文章中,美国塔夫茨大学的研究人员综述了利用丝蛋白构建先进光学器件的最新进展,作者重点关注了结构设计与最终光学功能之间的关系(Yushu Wang, Meng Li, Yu Wang. Silk: a versatile biomaterial for advanced optics and photonics [Invited][J]. Chinese Optics Letters, 2020, 18(8):80004)。