June 25, 2026: Prof Mark Herzik, University of California, San Diego

Old tools, new tricks: engineering better cryoEM sample preparation workflows through design and chemistry High-resolution single-particle cryoEM increasingly relies not only on advances in instrumentation and image processing, but on the ability to reproducibly generate high-quality specimens. However, sample preparation remains a major bottleneck, particularly for dynamic, oxygen-sensitive, or air–water interface (AWI)-prone systems. In this talk, I will present two complementary strategies from our lab aimed at overcoming persistent challenges in cryoEM sample preparation through workflow design and chemical intervention. First, I will describe the development of an anaerobic cryoEM pipeline that enables structural characterization of oxygen-sensitive macromolecular complexes under near-native and catalytically relevant conditions. This approach integrates controlled atmosphere sample handling, optimized vitrification strategies, and downstream analysis to capture transient functional states that are otherwise inaccessible. Second, I will highlight our recent work on SurfACT, a rationally designed surfactant cocktail that mitigates AWI-induced artifacts across a broad range of specimens. Through systematic formulation and an EMDB-wide analysis of additive usage, we demonstrate that low-concentration surfactant mixtures can improve particle distribution, preserve structural integrity, and reduce preferred orientation without the need for extensive sample-specific optimization. Together, these approaches illustrate how combining engineering principles with chemical insight can transform cryoEM sample preparation from a trial-and-error process into a more predictable and generalizable workflow. I will conclude with practical guidelines and perspectives on integrating these strategies into routine cryoEM pipelines.