The article provides an overview of structural DNA nanotechnology, which leverages the self-assembly properties of synthetic branched DNA and sticky-ended cohesion to create novel nanomaterials. Key aspects include: 1. **Hybridization**: The self-association of complementary nucleic acid molecules is fundamental to the construction of DNA-based structures. Sticky-ended cohesion, where hydrogen bonding between complementary ends forms stable connections, is a key component. 2. **Stably Branched DNA**: Branched DNA molecules, such as Holliday junctions and replication forks, are essential for creating complex structures. These molecules can form rigid motifs that are crucial for building periodic lattices and nanomechanical devices. 3. **Sequence Design and Symmetry Minimization**: Designing DNA sequences to minimize symmetry is crucial for controlling the structure and preventing unwanted self-assembly. This involves breaking symmetries and using specific sequence patterns to guide the formation of desired structures. 4. **Motif Design**: Motif design involves creating specific topological species through reciprocal exchanges between DNA strands. Examples include the DX motif, which has a persistence length twice that of linear duplex DNA, and the TX motif, which can act as a topographic marker in atomic force microscopy. 5. **2D and 3D Crystals**: Periodic matter can be created using robust motifs like the DX molecule. 2D crystals are often used to introduce students to the field, while 3D crystals are characterized by X-ray crystallography and can be used to study complex molecular structures. 6. **Nanomechanical Devices**: DNA nanotechnology has been used to create nanomechanical devices that change shape or function over time. These devices can be based on structural transitions, such as the B-Z transition in DNA, or sequence-dependent mechanisms, such as toehold-mediated transitions. 7. **Applications**: DNA nanotechnology has been applied to organize other molecular species, such as proteins and nanoparticles, and to create complex patterns and structures. It has also been used to develop algorithmic assembly methods and to explore the use of DNA analogs and semi-natural constructs. 8. **Future Prospects**: The field is rapidly growing, with increasing innovation and applications. The ability to control the structure and function of matter at the nanoscale using DNA is a powerful tool with potential applications in various fields, including medicine, electronics, and materials science. The article concludes by highlighting the importance of DNA nanotechnology in creating precise and programmable structures, and its potential for future advancements in nanoscale materials and devices.The article provides an overview of structural DNA nanotechnology, which leverages the self-assembly properties of synthetic branched DNA and sticky-ended cohesion to create novel nanomaterials. Key aspects include: 1. **Hybridization**: The self-association of complementary nucleic acid molecules is fundamental to the construction of DNA-based structures. Sticky-ended cohesion, where hydrogen bonding between complementary ends forms stable connections, is a key component. 2. **Stably Branched DNA**: Branched DNA molecules, such as Holliday junctions and replication forks, are essential for creating complex structures. These molecules can form rigid motifs that are crucial for building periodic lattices and nanomechanical devices. 3. **Sequence Design and Symmetry Minimization**: Designing DNA sequences to minimize symmetry is crucial for controlling the structure and preventing unwanted self-assembly. This involves breaking symmetries and using specific sequence patterns to guide the formation of desired structures. 4. **Motif Design**: Motif design involves creating specific topological species through reciprocal exchanges between DNA strands. Examples include the DX motif, which has a persistence length twice that of linear duplex DNA, and the TX motif, which can act as a topographic marker in atomic force microscopy. 5. **2D and 3D Crystals**: Periodic matter can be created using robust motifs like the DX molecule. 2D crystals are often used to introduce students to the field, while 3D crystals are characterized by X-ray crystallography and can be used to study complex molecular structures. 6. **Nanomechanical Devices**: DNA nanotechnology has been used to create nanomechanical devices that change shape or function over time. These devices can be based on structural transitions, such as the B-Z transition in DNA, or sequence-dependent mechanisms, such as toehold-mediated transitions. 7. **Applications**: DNA nanotechnology has been applied to organize other molecular species, such as proteins and nanoparticles, and to create complex patterns and structures. It has also been used to develop algorithmic assembly methods and to explore the use of DNA analogs and semi-natural constructs. 8. **Future Prospects**: The field is rapidly growing, with increasing innovation and applications. The ability to control the structure and function of matter at the nanoscale using DNA is a powerful tool with potential applications in various fields, including medicine, electronics, and materials science. The article concludes by highlighting the importance of DNA nanotechnology in creating precise and programmable structures, and its potential for future advancements in nanoscale materials and devices.