Molecular recruitment and release using DNA host condensates

Artificial biomolecular condensates are a promising tool to achieve spatial self-organization in active materials and synthetic cells. DNA branched motifs known as nanostars are a particularly versatile tool to build artificial condensates with customizable phase diagrams and viscoelastic properties. Here, we characterize how the inclusion of aptamers in DNA nanostars makes it possible to engineer condensates with the capacity of recruiting biomolecules of interest to the dense phase. Furthermore, we demonstrate how biomolecules can be released from condensates by supplying "kleptamer", an oligonucleotide that is complementary to the aptamer sequence. We focus specifically on incorporating a DNA aptamer that recruits streptavidin (SA), and investigate how the positioning of the aptamer-whether at the nanostar junction, or at the middle or tip of one of the nanostar arms-affects the formation of condensates and the recruitment efficiency of SA. We find that the aptamer's location within the nanostar does not significantly influence condensation and recruitment, nor the capacity of kleptamers to release the protein. These results provide new insight into the design of synthetic DNA condensates for the uptake and release of target molecules and demonstrate their robustness with respect to nanostar design, potentially broadening the use of such condensates in synthetic biology applications.