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Assembly of complex structures from a small set of tiles is a common theme in biology. For example, many copies of identical proteins make up polyhedron-shaped, viral capsids and tubulin can make long microtubules. This inspired the development of tile-based DNA self-assembly for nanoconstruction, particularly for structures with high symmetries. In the final structure, each type of motif will adopt the same conformation, either rigid or with defined flexibility. For structures that have no symmetry, their assembly remains a challenge from a small set of tiles. To meet this challenge, algorithmic self-assembly has been explored driven by computational science, but it is not clear how to implement this approach to one-dimensional (1D) structures. Here, we have demonstrated that a constant shift of a conformational equilibrium could allow 1D structures to evolve. As shown by atomic force microscopy imaging, one type of DNA tile successfully assembled into DNA spirals and concentric circles, which became less and less curved from the structure's center outward. This work points to a new direction for tile-based DNA assembly.

This manuscript introduces geometry as a means to program the tile-based DNA self-assembly in two and three dimensions. This strategy complements the sequence-focused programmable assembly. DNA crystal assembly critically relies on intermotif, sticky-end cohesion, which requires complementarity not only in sequence but also in geometry. For DNA motifs to assemble into crystals, they must be associated with each other in the proper geometry and orientation to ensure that geometric hindrance does not prevent sticky ends from associating. For DNA motifs with exactly the same pair of sticky-end sequences, by adjusting the length (thus, helical twisting phase) of the motif branches, it is possible to program the assembly of these distinct motifs to either mix with one another, to self-sort and consequently separate from one another, or to be alternatingly arranged. We demonstrate the ability to program homogeneous crystals, DNA "alloy" crystals, and definable grain boundaries through self-assembly. We believe that the integration of this strategy and conventional sequence-focused assembly strategy could further expand the programming versatility of DNA self-assembly.

p class="Text" style="margin: 0in 0in 8pt; text-align: justify; line-height: 24px; font-size: 12pt; font-family:quot;Times New Romanquot;, serif; color: rgb(0, 0, 0);"Non-canonical interactions in DNA remain under-explored in DNA nanotechnology. Recently, many structures with non-canonical motifs have been discovered, notably a hexagonal arrangement of typically rhombohedral DNA tensegrity triangles that forms through non-canonical sticky end interactions. Here, we find a series of mechanisms to program a hexagonal arrangement using: the sticky end sequence; triangle edge torsional stress; and crystallization condition. We showcase cross-talking between Watson-Crick and non-canonical sticky ends in which the ratio between the two dictates segregation by crystal forms or combination into composite crystals. Finally, we develop a method for reconfiguring the long-range geometry of formed crystals from rhombohedral to hexagonal anditalicvice versa/italic. These data demonstrate fine control over non-canonical motifs and their topological self-assembly. This will vastly increase the programmability, functionality, and versatility of rationally designed DNA constructs.o:p/o:p/p.

Tile-based DNA self-assembly is a powerful approach for nano-constructions. In this approach, individual DNA single strands first assemble into well-defined structural tiles, which, then, further associate with each other into final nanostructures. It is a general assumption that the lower-level structures (tiles) determine the higher-level, final structures. In this study, we present concrete experimental data to show that higher-level structures could, at least in the current example, also impact on the formation of lower-level structures. This study prompts questions such as: how general is this phenomenon in programmed DNA self-assembly and can we turn it into a useful tool for fine tuning DNA self-assembly?

This manuscript studies the impact of extruding hairpins on two-dimensional self-assembly of DNA tiles on solid surface. Hairpins are commonly used as tomographic markers in DNA nanostructures for atomic force microscopy imaging. In this study, we have discovered that hairpins play a more active role. They modulate the adsorption of the DNA tiles onto the solid surface, thus changing the tile assembly kinetics on the solid surface. Based on this discovery, we were able to promote or slow down DNA self-assembly on the surface by changing the hairpin locations on the DNA tiles. This knowledge gained will be helpful for the future design of DNA self-assembly on surface.

Construction of thermally and chemically robust metal–organic frameworks (MOFs) is highly desirable for postcombustion CO2 capture from flue gas containing water vapor and other acidic gases. Here ...

A major challenge in material design is to couple nanoscale molecular and supramolecular events into desired chemical, physical, and mechanical properties at the macroscopic scale. Here, a novel self-assembled DNA crystal actuator is reported, which has reversible, directional expansion and contraction for over 50 μm in response to versatile stimuli, including temperature, ionic strength, pH, and redox potential. The macroscopic actuation is powered by cooperative dissociation or cohesion of thousands of DNA sticky ends at the designed crystal contacts. The increase in crystal porosity and cavity in the expanded state dramatically enhances the crystal capability to accommodate/encapsulate nanoparticles/proteins, while the contraction enables a "sponge squeezing" motion for releasing nanoparticles. This crystal actuator is envisioned to be useful for a wide range of applications, including powering self-propelled robotics, sensing subtle environmental changes, constructing functional hybrid materials, and working in drug controlled-release systems.

Construction of thermally and chemically robust metal-organic frameworks (MOFs) is highly desirable for postcombustion CO

The development of a simple, robust, and generalizable approach for spatially controlled growth of metal-organic frameworks (MOFs) on diverse polymeric substrates is of profound technological significance but remains a major challenge. Here, we reported the use of adhesive bacterial amyloid nanofibers, also known as curli nanofibers (CNFs), major protein components of bacterial biofilms, as universal and chemically/mechanically robust coatings on various polymeric substrates to achieve controlled MOF growth with improved surface coverage up to 100-fold. Notably, owing to the intrinsic adhesive attributes of CNFs, our approach is applicable for MOF growth on both 2D surfaces and 3D objects regardless of their geometric complexity. Applying this technique to membrane fabrication afforded a thin-film composite membrane comprising a 760 ± 80 nm ZIF-8 selective layer grown on a microporous polyvinylidene fluoride (PVDF) support which exhibited a C3H6/C3H8 mixed-gas separation factor up to 10, C3H6 permeance up to 1110 GPU and operational stability up to 7 days. Our simple yet robust approach therefore provides new insights into designing new interfaces for mediating MOF growth and opens new opportunities for constructing new MOF-based membranes and devices.

A universal method to grow polymers on MOF surfaces with well-defined thickness, sequence and functionality., We report a generalizable approach to construct MOF@polymer functional composites through surface-initiated atom transfer radical polymerization (SI-ATRP). Unlike conventional SI-ATRP that requires covalent pre-anchoring of the initiating group on substrate surfaces, in our approach, a rationally designed random copolymer (RCP) macroinitiator first self-assembles on MOF surfaces through inter-chain hydrogen bond crosslinking. Subsequent polymerization in the presence of a crosslinking monomer covalently threads these polymer chains into a robust network, physically confining the MOF particle inside the polymer shell. We demonstrated the universality of this approach by growing various polymers on five MOFs of different metals (Zr, Zn, Co, Al, and Cr) with complete control over shell thickness, functionality and layer sequence while still retaining the inherent porosity of the MOFs. Moreover, the wettability of UiO-66 can be continuously tuned from superhydrophilic to superhydrophobic simply through judicious monomer(s) selection. We also demonstrated that a 7 nm polystyrene shell can effectively shield UiO-66 particles against 1 M H2SO4 and 1 M NaOH at elevated temperature, enabling their potential application in demanding chemical environments.