Jianjuan Jiang

Nanoscale probing of electron-regulated structural transitions in silk proteins by near-field IR imaging and nano-spectroscopy

Silk protein fibres produced by silkworms and spiders are renowned for their unparalleled mechanical strength and extensibility arising from their high-β-sheet crystal contents as natural materials. Investigation of β-sheet-oriented conformational transitions in silk proteins at the nanoscale remains a challenge using conventional imaging techniques given their limitations in chemical sensitivity or limited spatial resolution. Here, we report on electron-regulated nanoscale polymorphic transitions in silk proteins revealed by near-field infrared imaging and nano-spectroscopy at resolutions approaching the molecular level. The ability to locally probe nanoscale protein structural transitions combined with nanometre-precision electron-beam lithography offers us the capability to finely control the structure of silk proteins in two and three dimensions. Our work paves the way for unlocking essential nanoscopic protein structures and critical conditions for electron-induced conformational transitions, offering new rules to design protein-based nanoarchitectures.

High performance protein photolithography using photoreactive silk light chain as the resist: Material, method and mechanism

The Achilles heel of existing protein-based bio-photoresists is the inevitable wide molecular weight distribution during the protein extraction/regeneration process, hindering their practical uses in the semiconductor industry where reliability and repeatability are paramount. A wafer-scale high resolution patterning of bio-microstructures using well-defined silk fibroin light chain as the resist material is presented showing unprecedented performances. The lithographic and etching performances of silk fibroin short chain resists are evaluated systematically and the underlying mechanisms are thoroughly discussed. The micropatterned silk structures are evaluated as cellular substrates for the successful spatial guidance of fetal neural stems cells seeded on the patterned substrates. The enhanced patterning resolution, the improved etch resistance and the inherent biocompatibility of such protein-based photoresist provide new opportunities in fabricating large scale biocompatible functional microstructures.

Silk: New opportunities for an ancient material in MEMS/NEMS

This paper demonstrates potential uses of naturally regenerated/extracted silk proteins as a promising biopolymer platform for applications in micro- and nanofabrication with initial attempts and successes on commonly used pattern transfer techniques such as e-beam lithography, soft lithography and nano-imprinting.