Recording and Revealing 2.5D Nanopatterned Hidden Information on Silk Protein Bioresists

• Published in: Small (Weinheim an der Bergstrasse, Germany) Vol. 20; no. 44; pp. e2403169 - n/a
• Main Authors: Lee, Tae‐Yun, Choi, Juwan, Lee, Soohoon, Jeon, Heonsu, Kim, Sunghwan
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 01.11.2024
• Subjects: Amorphous materials; Amorphous structure; Biocompatibility; Biomedical materials; Electron beams; electron‐beam lithography; Fluorescence; Functional materials; Lithography; nanopattern; Nanotechnology devices; Patterning; polymorphic transition; security information; Silk fibroin; silk protein; security information; electron‐beam lithography; polymorphic transition; silk protein; nanopattern
• ISSN: 1613-6810; 1613-6829; 1613-6829
• DOI: 10.1002/smll.202403169

Nanopatterning on biomaterials has attracted significant attention as it can lead to the development of biomedical devices capable of performing diagnostic and therapeutic functions while being biocompatible. Among various nanopatterning techniques, electron‐beam lithography (EBL) enables precise and versatile nanopatterning in desired shapes. Various biomaterials are successfully nanopatterned as bioresists by using EBL. However, the use of high‐energy electron beams (e‐beams) for high‐resolutive patterning has incorporated functional materials and has caused adverse effects on biomaterials. Moreover, the scattering of electrons not absorbed by the bioresist leads to proximity effects, thus deteriorating pattern quality. Herein, EBL‐based nanopatterning is reported by inducing molecular degradation of amorphous silk fibroin, followed by selectively inducing secondary structures. High‐resolution EBL nanopatterning is achievable, even at low‐energy e‐beam (5 keV) and low doses, as it minimizes the proximity effect and enables precise 2.5D nanopatterning via grayscale lithography. Additionally, integrating nanophotonic structures into fluorescent material‐containing silk allows for fluorescence amplification. Furthermore, this post‐exposure cross‐linking way indicates that the silk bioresist can maintain nanopatterned information stored in silk molecules in the amorphous state, utilizing for the secure storage of nanopatterned information as a security patch. Based on the fabrication technique, versatile biomaterial‐based nanodevices for biomedical applications can be envisioned. Water‐based silk nanopatterning by electron‐beam lithography (EBL) based on post‐exposure cross‐linking allows for high precision 2.5D nanopatterning. This process is compatible with low‐energy EBL and therefore the proximity effect is minimized. Using the proposed process, a security application is demonstrated. The post‐exposure cross‐linking way allows for delivering the information hidden in the silk resist with no disclosure risk.