Abstract
Programmable self-assembly has recently enabled the creation of complex
structures through precise control of the interparticle interactions and the
particle geometries. Targeting ever more structurally complex, dynamic, and
functional assemblies necessitates going beyond the design of the structure
itself, to the measurement and control of the local flexibility of the
inter-subunit connections and its impact on the collective mechanics of the
entire assembly. In this study, we demonstrate a method to infer the mechanical
properties of multisubunit assemblies using cryogenic electron microscopy
(cryo-EM) and RELION's multi-body refinement. Specifically, we analyze the
fluctuations of pairs of DNA-origami subunits that self-assemble into tubules.
By measuring the fluctuations of dimers using cryo-EM, we extract mechanical
properties such as the bending modulus and interparticle spring constant. These
properties are then applied to elastic models to predict assembly outcomes,
which align well with experimental observations. This approach not only
provides a deeper understanding of nanoparticle mechanics, but also opens new
pathways to refining subunit designs to achieve precise assembly behavior. This
methodology could have broader applications in the study of nanomaterials,
including protein assemblies, where understanding the interplay of mechanical
properties and subunit geometry is essential for controlling complex
self-assembled structures.