Affinity-tag-based microfluidic protein isolation enables high-resolution Cryo-EM from minimal starting material

Cryo-EM has become central to high-resolution structure determination, but conventional sample preparation consumes substantial quantities of purified protein and relies on multi-step workflows that can destabilize sensitive complexes. Microfluidic approaches can downscale and accelerate these workflows while retaining the particle numbers required for single-particle analysis. Here, we present a generalized microfluidic isolation strategy that captures proteins directly from cell lysates or in vitro translation (IVT) reactions via genetically encoded tags rather than target-specific binders. Both affinity-based (ALFA-nanobody) and covalent (SpyTag3/SpyCatcher3) capture are supported. Specif