Organic Chemistry: Current Research
Open Access

Controlled 3d nano-sculpturing and nano-sintering of silk proteins using electron beam lithography

3^rd International Conference on Organic and Inorganic Chemistry

July 17-19, 2017 Chicago, USA

Nan Qin, Shaoqiang Zhang and Hu Tao

SIMIT, China
UT Austin, USA

Posters & Accepted Abstracts: Organic Chem Curr Res

Abstract :

Silk protein fibers produced by silkworms and spiders are renowned for their unparalleled mechanical strength and extensibility arising from their high-�²-sheet crystal contents as natural materials. Recently, exciting opportunities for silks in photonics, implantable bioelectronics and nanostructured scaffolds have been reported, revealing the need for innovative approaches to multi-scale fabrication with precision and manufacturing scalability. Silk was reported to be used either as a positive or negative EBL resist through interactions with electron beams given its polymorphic crystalline structure. The water-soluble film can be rendered insoluble by inducing crystallization (that is, beta sheet formation) of the silk protein. The inelastic collision of electrons with crystalline silk results in the formation of short polypeptides which are water-soluble. While in negative EBL using silk proteins where water radiolysis dominates, high electron beam doses are usually needed to form the intermolecular crosslinks to make the proteins water-insoluble. Either amorphous or crystalline silk can be used in both positive and negative tones by tuning the applied electron dosage. Furthermore, we report here for the first time, for crystalline silk exposed to the electron beam, scission of the crosslinked �²-sheets tends to occur from top to bottom, resulting in the removal of materials after a water-based development, which is referred to as electron-nano-sculpturing (subtractive manufacturing). In contrast, for the amorphous silk exposed to the electron beam, crosslinking of unordered random coils (either intrinsic or deformed from crystalline proteins upon electron irradiations) proceeds from bottom to top, which is referred to as electron-nanosintering (additive manufacturing). Spider silk protein synthesized through genetic engineering with well-defined molecular structure (i.e., average molecular weight and molecular weight distribution) shows better performances (e.g., resolution, contrast and mechanical property) than silk fibroin extracted from natural silk cocoons. These new findings offer new rules to design protein-based architectures of unprecedented resolution and flexibility.

Biography :

Email: qinnan@mail.sim.ac.cn