Programming Aggregate States of DNA Nanorods with Sub-10 nm Hydrophobic Patterns for Tunable Cell Entry

Isothermal Disorder-to-Order Transitions of DNA Origami Structures Induced by Alternative Component Subsets

DNA origami technology has shown potential across various applications, including the construction of molecular machines. Among these, mimicking the complex structural transitions of natural biomolecules in physiological environments remains a long-standing pursuit. Here, inspired by intrinsically disordered proteins, we propose a strategy for inducing disorder-to-order transitions in DNA origami structures at room temperature using alternative component subsets. In a triangular DNA origami model, we define three subsets of its constitutional DNA staples based on their spatial distributions along the scaffold. Atomic force microscopy and molecular dynamics simulations show that the individual subsets result in metastable assemblies with disordered morphologies and elevated free-energy fluctuations compared with those generated by the complete set of staples. Notably, after the addition of the remaining staples, the irregular structures transform into ordered triangular architectures within 2 h at room temperature, achieving yields of up to ∼60%. These findings suggest that these controlled folding pathways in DNA origami can robustly converge on the global energy minimum at room temperature, thereby providing a promising alternative strategy for engineering biomimetic DNA molecular machines.

Close Proximity of Cholesterol Anchors in Membrane Induces the Dissociation of Amphiphilic DNA Strand from Membrane Surface

Dynamic DNA nanotechnology is appealing for membrane surface engineering due to their versatility and programmability. To modulate the dynamic interactions between the DNA functional units immobilized on membrane surface, membrane-anchored DNA functional units often come into close proximity each other due to DNA base pairing, which also leads to the close contact of the hydrophobic anchors in membrane. However, whether the close contact of hydrophobic anchors induces the dissociation of amphiphilic DNA structures from membrane surface is not concerned. Herein, we utilized cholesterol-labelled single-stranded DNA (ssDNA) as a simplified amphiphilic DNA structure to investigate the stability of membrane anchored DNA strands upon the closely contact of cholesterol anchors. The close contact of cholesterol-labelled ssDNA molecules driven by toehold mediated strand displacement reaction leads to approximately 41 % membrane anchored ssDNA dissociation from membrane surface, indicating the proximal cholesterol anchors in membrane could reduce the anchoring stability of cholesterol-modified DNA strands. This work enhances our understanding of the interactions between amphiphilic DNA and membranes, and provides valuable insights for the design of future DNA constructs intended for applications involving dynamic DNA reactions on membrane surface.

Directing the Encapsulation of Single Cells with DNA Framework Nucleator-Based Hydrogel Growth

Encapsulating individual mammalian cells with biomimetic materials holds potential in ex vivo cell culture and engineering. However, current methodologies often present tradeoffs between homogeneity, stability, and cell compatibility. Here, inspired by bacteria that use proteins stably anchored on their outer membranes to nucleate biofilm growth, we develop a single-cell encapsulation strategy by using a DNA framework structure as a nucleator (DFN) to initiate the growth of DNA hydrogels under cell-friendly conditions. We find that among the tested structures, the tetrahedral DFN can evenly and stably reside on cell membranes, effectively initiating hybridization chain reactions which generate homogeneously dense yet flexible single-cell encapsulation for diverse cell lines. The encapsulation persists for up to 72 hours in a serum-containing cell culture environment, representing a ~70-fold improvement compared to encapsulations mediated by single-stranded DNA nucleators. The metabolism and proliferation of the encapsulated cells are suppressed, but can be restored to the original efficiencies upon release, suggesting the superior cell compatibility of the encapsulation. We also find that compared to naked cells, the encapsulated cells exhibit a lower autophagy level after undergoing mechanical stress, suggesting the protective effect of the DNA encapsulation. This method may provide a new tool for ex vivo cell engineering.