title: Biopatterning of Silk Proteins for Soft Micro-optics.
abstract: Silk proteins from spiders and silkworms have been proposed as outstanding candidates for soft micro-optic and photonic applications because of their optical transparency, unique biological properties, and mechanical robustness. Here, we present a method to form microstructures of the two constituent silk proteins, fibroin and sericin for use as an optical biomaterial. Using photolithography, chemically modified silk protein photoresists are patterned in 2D arrays of periodic patterns and Fresnel zone plates. Angle-dependent iridescent colors are produced in these periodic micropatterns because of the Bragg diffraction. Silk protein photolithography can used to form patterns on different substrates including flexible sheets with features of any shape with high fidelity and resolution over large areas. Finally, we show that these mechanically stable and transparent iridescent architectures are also completely biodegradable. This versatile and scalable technique can therefore be used to develop biocompatible, soft micro-optic devices that can be degraded in a controlled manner.
authors: †Department of Chemical and Life Science Engineering Virginia Commonwealth University, Richmond, Virginia 23284, United States.
authors: Ramendra K
authors: RK
authors: Pal
authors: †Department of Chemical and Life Science Engineering Virginia Commonwealth University, Richmond, Virginia 23284, United States.
authors: Nicholas E
authors: NE
authors: Kurland
authors: †Department of Chemical and Life Science Engineering Virginia Commonwealth University, Richmond, Virginia 23284, United States.
authors: Congzhou
authors: C
authors: Wang
authors: ‡Department of Biotechnology, Indian Institute of Technology, Kharagpur 721302, India.
authors: Subhas C
authors: SC
authors: Kundu
authors: †Department of Chemical and Life Science Engineering Virginia Commonwealth University, Richmond, Virginia 23284, United States.
authors: Vamsi K
authors: VK
authors: Yadavalli
mesh_terms: D000818:Animals; D001672:Biocompatible Materials / Q000737:chemistry*; D012831:Bombyx; D005349:Fibroins / Q000737:chemistry* / Q000648:ultrastructure; D049449:Luminescence; D008422:Materials Testing; D018625:Microscopy, Atomic Force; D061848:Optical Imaging; D055095:Optics and Photonics / Q000379:methods*; D059748:Proteolysis; D047030:Sericins / Q000737:chemistry* / Q000648:ultrastructure
chemical_list: D001672:Biocompatible Materials; D047030:Sericins; D005349:Fibroins
keywords: Fresnel lens; iridescence; microfabrication; photolithography; silk protein; soft optics