(6fk) Silk-Based Materials: A Sustainable Route Towards Multifunctional Material Applications

Silk fibroin protein, a natural biopolymer derived from the cocoons of silkworm, has received considerable attention due to its excellent biocompatibility, controllable biodegradability, outstanding mechanical strength, and versatile aqueous processability into new material formats. These properties make silk protein-based materials suitable candidates for biomedical applications. Additionally, in the last few years, silk has been also recognized as an attractive material for emerging fields, such as environmentally adaptive materials, flexible/wearable electronics, photonics, optics, sensing, and energy conversion/storage systems. These newer utilities derive from: (1) the ability of silk to be formed into unique nanoarchitectures through hierarchical self-assembly for processing into various material formats, such as films, nanofibers, hydrogels, and sponges, with high fidelity feature resolution down to the nanoscale, and (2) the availability of silk as an abundant natural resource with eco-friendly properties that can help meet the growing demand for sustainable materials and devices.

My research interests are the synergistic integration of natural and synthetic building blocks that can create functional materials, with a focus on thin film, nanofiber, and hydrogel formation, for applications in catalysis, miniaturized energy conversion/storage, sensing and adsorption/separation systems. Specifically, by understanding the fundamental structure-property relationships of silk fibroin at the nanoscale, my research aims to leverage silk, metal organic framework (MOF), polymer, and block copolymer materials to formulate hierarchical structures with tunable functional properties, which can be transferred from molecular to the macroscopic length scales.

At the initial stage of my independent research, I plan to focus on following topics.

(1) Highly Ordered Nitrogen-Doped Graphitic Carbon Thin Films with Tailored Micropores/Mesopores for Micro-Supercapacitor Applications. This would involve the study of crystallization of silk thin films that can be transformed into ordered graphitic carbons in the form of films from β-sheet nanocrystals.

(2) Hybrid Silk/MOF Thin Films, Nanofibers, and Aerogels for CO₂ Adsorption/Separation, Air or Water Filtration, and Chemical Sensor Applications. This would entail the precise control of the position of ordered crystalline MOFs.

(3) Stretchable Ionic Conductive Silk Hydrogels for Human Health Monitoring. I am interested in a variety of sacrificial bonds and conducting components compatible with silk matrices to fabricate tough and ionic conductive hydrogels.

Research Experience:

My Ph.D. research in the Polymer Science and Engineering Department at the University of Massachusetts Amherst (with Professor Thomas Russell and Professor Kenneth Carter) focused on the understanding of the minimum amount of topographic patterning necessary to successfully guide the self-assembly of block copolymers in 2D and 3D. During this time, I developed expertise in block copolymer lithography that can fabricate highly ordered nanostructures (hexagonal arrays or line patterns) over macroscopic length scales. In addition, I quantitatively analyzed these nanostructures using grazing incidence small angle X-ray scattering (GISAXS). These studies have increased our understanding of the morphological characteristics and lateral ordering of the self-assembled block copolymer microdomains guided by the patterned substrates for the magnetic bit-patterned media applications and the fabrication of various next-generation functional nanostructures.

During my postdoctoral research in the Department of Biomedical Engineering at Tufts University (with Professor David Kaplan), I have broadened my research experience in silk-based biomaterials. Building on my graduate research experience in polymer science and engineering, I have developed Fenton reactions that can oxidize the tyrosine residues of silk fibroin, leading to dityrosine crosslinking that enables the formation of chemically crosslinked silk hydrogels for biomedical applications. This study hinted at the use of Fenton reaction to create a silk hydrogel system with enhanced mechanical properties, while overcoming the potential concerns (e.g., immunological response) with enzymatically crosslinked hydrogels. In particular, this work has increased our understanding of the interaction of iron ions with silk fibroin that could be used to modulate the degree of dityrosine crosslinking.

Teaching Interests:

My teaching interests include core courses in chemical engineering, including fluid mechanics, heat transfer, mass transfer, thermodynamics, chemical reaction engineering, and separation engineering. In addition, with my multidisciplinary research background, I am also interested in teaching polymer science and engineering, nanomanufacturing, and materials characterization both for undergraduate and graduate levels.