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.