DNA Condensates via Entanglement of String-like Structures Based on Anisotropic Nanotetrahedra

Biomolecular condensates are attracting attention for their bioinspired functionalities and potential applications. However, the influence of biomolecular structural properties on the complex phase behaviors of biomolecular condensates remains poorly understood. In particular, the effect of component anisotropicity on condensates has been largely overlooked despite the existence of highly anisotropic biological condensates, such as heterochromatin. In this study, we report the formation of DNA condensates based on tetrahedron-shaped DNA nanostructures (Tetra-motifs). We designed an anisotropic Tetra-motif with two distinct pairs of sticky ends. Linkers corresponding to the stronger pair were introduced to form connections between Tetra-motifs. Unlike the flexible X-branched DNA nanostructures (X-motifs), the rigid and anisotropic structure of Tetra-motifs enabled their concatenation into extended, string-like structures. We found that these string-like structures of Tetra-motifs formed condensates even without cross-linking of multivalent motifs, relying solely on entanglement of these string-like structures. Mechanical and microfluidic experiments revealed that the resulting string-based condensates are highly deformable. Furthermore, we demonstrated the control of this string-based condensate by external stimuli, including UV irradiation and temperature changes, suggesting its potential as a stimuli-responsive material.