Date Published: December 27, 2018
Publisher: John Wiley and Sons Inc.
Author(s): Xiaoqing Cai, Zhitao Zhou, Tiger H. Tao.
Physically transient optics, a form of optics that can physically disappear with precisely controlled degradation behaviors, has widespread applications including information security, drug release, and degradable implants. Here, a set of silk‐based programmable vanishing, biologically functional, multichromatic diffractive optical elements (MC‐DOEs) is reported. Silk proteins produced by silkworms and spiders are mechanically robust, biocompatible, biodegradable, and importantly, optically transparent, which open up new opportunities for a set of fully degradable transient optical devices with no need of metallic or semiconductor components. Compared with monochromatic DOEs, MC‐DOEs carry out richer information for more practical applications such as encryption and decryption of multilevel information, quantitative sensing/monitoring of chemical/biological cascade reactions, and effective treatment of infections caused by multiple pathogens.
Silk Solution Preparation: The established purification protocols were used to prepare silk fibroin.30 Bombyx mori cocoons were boiled for 30 min in aqueous 0.02 m Na2CO3 (Sigma‐Aldrich, USA) and then rinsed for 3 × 30 min in distilled water to remove the Na2CO3 and sericin. The degummed cocoons were dried for more than 12 h and then subsequently dissolved in 9.3 m LiBr (Sigma‐Aldrich, USA) solution at 60 °C for 4 h. The solution was dialyzed for 2 d in distilled water by using Slide‐a‐Lyzer dialysis cassettes (MWCO 3500, Pierce, USA) and then centrifuged for 2 × 20 min at 18 000 rpm. The final concentration was roughly 6.9 wt%, which was determined by measuring a volume of solution and the final dried weight.
The authors declare no conflict of interest.