SEMINAR
DEPARTMENT OF CHEMICAL ENGINEERING

Synthesis and Application of Silk and Silk-Mimetic Materials

Professor R. Helen Zha
Department of Chemical & Biological Engineering, RPI

Abstract

Silk fibroins are a class of proteins produced by a variety of insects and arachnids that can surpass man-made materials in specific strength and toughness. From a macromolecular perspective, silk fibroins have a linear architecture predominantly consisting of regularly alternating β-sheet forming peptide segments and flexible peptide segments, resulting in a supramolecular network structure with stiff crystalline domains reinforcing an amorphous matrix. In nature, silk fibroins undergo a complex self-assembly process during spinning, rapidly transitioning from a soluble protein to an insoluble, highly robust material. Our work aims to develop new synthetic methods to produce silk-mimetic macromolecules with well-defined chemical structures and targeted material properties. Moreover, we aim to leverage the self-assembly of silk fibroin and silk-mimetic macromolecules to form functional materials. In particular, we have observed that non-specific interactions of silk fibroin with surfaces during macromolecular self-assembly can lead to the formation of stable and substrate-tolerant thin-film coatings. These coatings provide complete surface coverage and can grow to tens of nanometers thick, thereby transforming the physicochemical properties of a surface without requiring substrate pre-activation or covalent chemistries. Our studies have demonstrated that silk fibroin coatings can be formed on a variety of substrates ranging from hydrophobic Teflon to hydrophilic TiO2. Furthermore, these coatings can readily exhibit beneficial properties for bacterial resistance and neural tissue regeneration. Our research moreover delves into the complex interplay of surface-protein and protein-protein interactions underlying coating formation to establish methods by which we can tune the coating process.

Biography

Dr. Helen Zha obtained her B.Sc. (2007) from MIT in Materials Science & Engineering with a focus on polymeric materials. She then received her Ph.D. (2013) from Northwestern University, where she worked as an NSF Graduate Research Fellow on self-assembling peptide-based materials. From 2013 - 2016, Helen pursued postdoctoral research at Eindhoven University of Technology in the Netherlands, where she developed supramolecular materials with highly ordered nanostructure and photoswitchable properties. In the fall of 2016, Helen moved to UC Berkeley, where she worked on antimicrobial coatings inspired by mussel adhesive proteins and spider silk. Helen started a position as tenure-track Assistant Professor at Rensselaer Polytechnic Institute in the Department of Chemical & Biological Engineering in January 2018. Her research group seeks to develop biohybrid and bioinspired materials for applications in human healthcare and sustainability.