Topology-Based Dual Lock-and-Key Structures for Hydrogel Self-Assembly in Macroscopic Supramolecular Assembly

Macroscopic supramolecular assembly (MSA), which refers to the assembly of building blocks at a macroscopic scale, holds great potential for the fabrication of ordered bulk structures. Thanks to the high design flexibility of the building blocks and the precise controllability of the assembly process, MSA has found applications in a wide range of fields, including the fabrication of tissue scaffolds, soft actuators, and more. Additionally, among the candidates for building blocks, hydrogels are highly favored due to their easily tunable properties and diverse type with different characteristics. In MSA, two challenges need to be addressed to achieve a high level of assembly: enhancing the precision of assembly and increasing the number of orthogonally matching pairs. To date, despite numerous attempts, none have effectively tackled both challenges simultaneously. In this study, we introduce topology-based design criteria for achieving precise and selective self-assembly of hydrogel building blocks. We suggest a unique design approach termed “dual lock-and-key structures,” In this design model, only topologically matching pairs can be assembled with exceptional precision. Through the implementation of dual lock-and-key structures, we establish principles for the selection of multiple orthogonally matching pairs. We demonstrate the selective assembly of both simple one-to-one matching and complex one-to-many assemblies. Moreover, by harnessing the easy property tunability of hydrogel, we synthesize DNA-mimicking single-stranded structures, which hybridize into double-stranded structures with sequence-specific arrangements. Finally, we present a hydrogel logic gate system, consisting of a YES gate, an OR gate, and an AND gate. Utilizing the high selectivity of our dual lock-and-key structures, the desired outputs are exclusively obtained when the appropriate building blocks are assembled, following the logic of each gate: YES, OR, and AND.