Qian Chen - Materials Seminar

Electron Videography of Dynamic Matter: From Soft, Biological to Energy Materials

Qian Chen
University of Illinois, Urbana-Champaign 
Professor, Department of Materials Science and Engineering

My group’s primary research theme is to understand and manipulate the organization of complex synthetic materials and biological entities in space and time at the underexplored nanoscale. Our research spans seemingly disparate systems, including nanoparticle (NP) assemblies as reconfigurable metamaterials, separation membranes for wastewater reclamation and critical-element recovery, multivalent-ion batteries for grid-energy storage, and membrane proteins and immune cells that regulate signaling underlying enzymatic catalysis, synaptic transmission, and cancer immunotherapy. Despite their apparent differences, these systems are unified by one central idea: we can only engineer what we can image. We have therefore focused on developing and applying “electron videography”, to use electron microscopy to capture materials and biological systems at spatiotemporal resolutions previously inaccessible. In this talk, I will discuss three examples. First, I will describe the synthesis and self-assembly of colloidal NPs. Using liquid-phase transmission electron microscopy (TEM) and single-particle tracking, we directly visualize NP crystallization into superlattices and uncover pathways unique to the nanoscale for advanced crystal engineering. We further extend to measure phonon dispersions in NP superlattices and the synthesis of atomically stenciled patchy NPs, connecting NPs to the design of mechanical metamaterials. Second, I will discuss biological systems, including real-time “fingering” fluctuations of membrane proteins and three-dimensional imaging of immune synapses formed between T cells and dendritic cells using high-throughput volume electron microscopy, revealing molecular and cellular architectures that underlie biological function. Third, I will discuss defect-rich solids, where we extend direct imaging to multivalent-ion batteries, catalysts, and critical minerals. Here, three- and four-dimensional electron microscopy reveals how heterogeneous strain, defects, and local structural transformations generate distinct spatial patterns and ultimately influence materials properties. Together, these examples illustrate how “electron videography” can provide crucial and complementary insights across materials and biological systems, with the common goal of imaging, understanding, and ultimately manipulating matter in space and time at the nanoscale.