: Soon-Chun Chung, Joon-Song Park, Rakesh Kumar Jha, Jieun Kim, Jinha Kim, Muyoung Kim, Juwan Choi, Hongdeok Kim, Da-Hye Park, Narendar Gogurla, Tae-Yun Lee, Heonsu Jeon, Ji-Yong Park, Joonmyung Choi, Ginam Kim, and Sunghwan Kim

: ACS Appl. Mater. Interfaces 14(51), 56623–56634(2022)

DOI https://doi.org/10.1021/acsami.2c17843 Silk protein is being increasingly introduced as a prospective material for biomedical devices. However, a limited locus to intervene in nature-oriented silk protein makes it challenging to implement on-demand functions to silk. Here, we report how polymorphic transitions are related with molecular structures of artificially synthesized silk protein and design principles to construct a green-lithographic and high-performative protein resist. The repetition number and ratio of two major building blocks in synthesized silk protein are essential to determine the size and content of β-sheet crystallites, and radicals resulting from tyrosine cleavages by the 193 nm laser irradiation induce the β-sheet to α-helix transition. Synthesized silk is designed to exclusively comprise homogeneous building blocks and exhibit high crystallization and tyrosine-richness, thus constituting an excellent basis for developing a high-performance deep-UV photoresist. Additionally, our findings can be conjugated to design an electron-beam resist governed by the different irradiation–protein interaction mechanisms. All synthesis and lithography processes are fully water-based, promising green lithography. Using the engineered silk, a nanopatterned planar color filter showing the reduced angle dependence can be obtained. Our study provides insights into the industrial scale production of silk protein with on-demand functions.