(2ja) Hierarchical Structuring of Biopolymers for Environmental Nanotechnologies

Significant implications exist between achieving ambitious climate mitigation goals and sustainably feeding the world's growing population. By 2050, the global population is projected to increase by nearly 2 billion, leading to increased food demand. However, the intensified use of input materials such as agrichemicals and the generation of waste like wastewater in food production processes exert increased pressure on the environment. In addressing these challenges, environmental nanotechnologies play a crucial role within the realm of precision agriculture and water treatment. These technologies optimize agricultural processes, maximize productivity, and minimize resource use and environmental impact. For instance, hierarchical materials adorned with multifunctional nano- and microornamentations have a pivotal role in controlled delivery, water filtration, soft robotics, energy storage, sensing, and environmental remediation. However, current strategies face challenges in achieving controllable hierarchical assembly across a wide range of materials.

My research focuses on the hierarchical structuring of soft materials, such as biopolymers and colloidal suspensions, to create multifunctional delivery vehicles, reaction vessels, and fluidic channels for environmental nanotechnologies. Through my work, I aim to provide fundamental knowledge of polymer chain hierarchical assembly, demonstrate the multifunctionality of hierarchical biodegradable structures, and guide the development of advanced and sustainable designs for agriculture, water treatment, and other environmental technologies.

I am developing a vapor-induced synergistic differentiation (VISDi) method for biopolymers self-assembling into hierarchical structures. The VISDi technique uses environmental stimuli (such as vapor), allowing the biopolymer microspheres to synergistically differentiate into an echinate micro-network or multiple microspines with structural gradients. We conduct experiments and simulations to explain the assembly process. The results also indicate that the VISDi process barely affects the biopolymer’s secondary structure and keeps its tunability in post-processing. This simple, fast, low-intensity self-assembly route applies to a variety of natural and synthetic polymer systems (including silk fibroin, chitosan, methyl cellulose, pectin, PVP, PAA, and PVA). For advanced functions, we can tune the fabricated end structures in materials, morphologies, crystallinity, payload, and mechanical properties. For example, we apply the microspines in adhesive microcapsule retention on plant leaves. In particular, the engineering of spiny microcapsules effectively improved the retention percentage by a factor of 12.5 on smooth spinach leaves after wash-off. Furthermore, the echinate micro-network can transfer and co-localize different fluorescent payloads in the micro-bridges.

My research also includes the design and fabrication of biodegradable microcapsules to replace some primary microplastics used in agriculture and cosmetics. I collaborated with BASF SE and developed a silk-based microencapsulation technique that could provide an inexpensive and easily manufactured substitute. I controlled the payload release and lifetime for different applications. In the greenhouse test, our silk-based herbicide proved to perform better on crops than an existing commercial product. Besides, I am developing biopolymer-based two-dimensional nanosheets as delivery vehicles or vessels by integrating my previous research in graphene-based 2D nanochannels for intercalation, fast transport, and slow release.

Teaching Interests

I enjoy teaching students from all knowledge levels. My Ph.D. advisor is from the Chemical Engineering department. Therefore, I took courses from both ChemE and Chemistry departments and published papers on filtration membranes and nanofluidics. I believe that my background and teaching experience enable me to teach the core courses in materials science and engineering, chemical and environmental engineering, and chemistry.

At Brown, I served as a teaching assistant for “CHEM 0100 - Introductory Chemistry” and “CHEM 0330 - Equilibrium, Rate, and Structure” for two semesters. During these courses (each around 300 students), I facilitated problem sessions, graded assignments, and exams, and held weekly office hours. I mentored one undergraduate and one master in my lab for their graduation projects. I helped the students outline and carry out their research projects, set regular one-on-one or team meetings, and provided feedback promptly. As a result, two of my mentees successfully graduated, and the master’s student and I co-authored a paper in a prestigious journal.

In my MIT Kaufman Teaching Certificate Program in 2020, I designed a course related to my expertise (Characterizing Material Structure), tailored the content into a six-page syllabus, and performed microteaching for a group of students and postdocs from different disciplines. I organized my teaching materials with backward design, scaffolding, and formative and summative assessments. I explicitly pointed out our intended learning outcomes during my teaching and built students’ belongings with a quiz on microscope images from daily TV commercials. In my Leadership and Professional Strategies and Skills training, I also learned many inclusive methods of grouping students, getting responses in class, and collecting feedback after class.

I have mentored for the Institute at Brown for Environment and Society - Leadership Alliance Program. I co-led a study group of six undergraduate students from underrepresented groups in this summer program. My goal was to help them learn about the research process and deliver oral or poster presentations of their summer projects. I first self-learned the course materials, including framing the research problem, significant statements, the research cycle, writing an abstract, and so on. Then I designed the contents into teaching slides and hosted 16 study sessions. During my office hours, I helped them with the issues in their summer projects and communications with their faculty advisors. As a result, all six students successfully presented their summer projects at the 2020 Leadership Alliance National Symposium. Besides, I helped with their graduate school applications, and one of the students has been admitted to a Ph.D. program at the University of South Carolina.

I gave scientific research showcases or talks to the public, including Cambridge Science Festival and Brookline Public Schools in Massachusetts. I showcased the silk boiling, food coating procedures, and silk-Vitamin C microcapsule products to the public and presented silk as an alternative to some microplastics. Communicating with non-scientists keeps reminding me of the original curiosity of beginners toward science. These experiences help me prepare materials with significant consideration of prior knowledge and a general sense of belonging, which apply to teaching and research proposals.