(2ek) Nano-Bio Interface Engineering with Precise Polymeric Nanostructures

The sustained growth in nanotechnology over the past two decades has greatly increased our capability to precisely engineer nanostructured materials at length scales between 1–10² nm. Meanwhile, tools developed in nanotechnology have led to significant progress in nanobiotechnology, enabling applications in nanomedicine, biomedical devices, and biosensors. The critical interface between nanostructured materials and biological systems–the nano-bio interface, plays a major role in controlling the adhesion, recognition, response when nanomaterials interface with biological systems in the aforementioned applications. However, the spatial resolution and accuracy we have achieved in nanotechnology have not been fully exploited to accelerate our understanding and capability to precisely control biochemical, biophysical interactions, therefore desirable properties of the nano-bio interface, to unravel new opportunities for human health and environment.

My future research program aims to engineer the critical nano-bio interface at the underexplored nanometer length scale, through precisely defined polymeric materials that are synthesized and assembled by design, or nanofabricated into accurate nanostructures. I will leverage precise (bio)polymers including polypeptides, polypeptoids, polynucleotides, as building blocks and interfacial materials, with which the chemical structure, molecular conformation, and organization of the polymer chains can be precisely controlled. As a result, we will be able to tailor the interactions that govern the interfacial properties and interfacial phenomena down to the single molecule level at the nano-bio interface. With the precise nature and large parameter space unique to sequence-defined polymers, my research will adopt two major approaches through i) rational design of polymers based on established structure–property relationships, and ii) high-throughput screening of material libraries (e.g., libraries created by the one-bead-one-compound (OBOC) method), to generate on-demand nanomaterials and nanostructured interfaces for desired nano-bio interface required by corresponding applications. My future independent research program will develop materials, establish design rules and engineering pathways to understand, control, and manipulate the nano-bio interface to harness the potential from the combination of nanotechnology and precise, functional bio/bioinspired materials.

Research Experience

Throughout my doctoral and postdoctoral research, I have devoted my research efforts to molecular-level design, synthesis, and nanofabrication of polymers towards understanding structure–property relationships and building nanometer-scale structures and surfaces. My research background and training uniquely position me to lead a vigorous and interdisciplinary research program leveraging sequence-defined polymer design and synthesis, polymer self-assembly, nanofabrication, and advanced characterization techniques (light/X-ray/neutron scattering, scanning probe and electron microscopy).

Nanopatterned, sequence-defined polymer brushes for semiconductor/bio interfaces

Molecular Foundry and Center for High Precision Patterning Science (CHiPPS) EFRC, Lawrence Berkeley National Laboratory (Advisor: Ricardo Ruiz, Ronald Zuckermann)

My postdoctoral research aims to engineer semiconductor/bio interfaces through nanopatterning precisely designed polymer brushes. We developed sequence-defined polymer brushes as an efficient, precisely tunable surface modification material platform for semiconductor substrates, with which we have i) demonstrated processing compatibility with nanofabrication workflows involving electron-beam lithographical patterning, and ii) achieved selective surface binding of biomacromolecules (DNA origami, streptavidin protein) down to the individual building block length scale (sub-100 nm) (Yu and Ruiz et al., Manuscript in preparation). The established nanopatterned polymer brush platform has now branched into collaborative user projects for single-molecule studies.

My recent postdoctoral research also includes developing and understanding polymers as growth promoters for area-selective atomic layer deposition (ALD) of metal oxides (Yu and Ruiz, US patent application 63/497,825), which has evolved into a collaborative effort towards high precision pattern transfer in the Center for High Precision Patterning Science (DOE Energy Frontier Research Center).

Polymer chain conformation effects on the thermodynamics of block copolymer self-assembly
Department of Chemical Engineering, University of California, Santa Barbara (Advisor: Rachel Segalman)

My doctoral research is focused on the fundamental polymer physics of how non-ideal chain shapes impact self-assembly, by incorporating bioinspired, sequence-defined polymers–polypeptoids, into block copolymers. I experimentally determined the chain conformation characteristics of polymers with designed helical secondary structures as opposed to unstructured coil polymers (Yu and Segalman et al. ACS Macro Lett. 2020, 9, 849), and determined the impact of chain conformation on the thermodynamics of block copolymer self-assembly (Yu and Segalman et al. Macromolecules 2019, 52, 2560). With precisely definable block copolymers, I further demonstrated that small conformational variations at the interface drive different morphologies of block copolymers, finding preferrable designs to access complex network phases (Yu and Segalman et al. Macromolecules 2021, 54, 5388).

Teaching Interests

Teaching and mentoring have always been parts of an academic career I am excited about, and I am constantly impressed and inspired by the rewarding experience of seeing one learn and grow through such processes. The chief philosophy of my teaching and mentoring is to train undergraduate and graduate students as ethical, technically strong chemical engineers and scientists, and to motivate students to pursue their careers with interests discovered and developed along the course. I view teaching as an evolving process as I interact with more students, and I am committed to constantly improving my own teaching throughout my academic career.

With my chemical engineering background and teaching experiences, I am comfortable teaching chemical engineering core courses including thermodynamics, transport, kinetics and reaction engineering at both undergraduate and graduate levels. In addition, I would be excited to teach and/or develop courses in polymer physics, polymer chemistry, advanced characterization techniques, nanofabrication, based on my graduate and postdoctoral research experience.