the construction of functional 2D materials by the self-assembly of synthetic building blocks such as amphiphilic block copolymers, [10] lipid molecules, [11] deoxyribonucleic acids (DNAs), [12] rod-coil amphiphiles, [13] and oligopeptides. [14] Among diverse self-assembling modules, aromatic amphiphiles can serve as remarkable candidates for the creation of well-defined supramolecular 2D structures owing to their rigidity and the π-π stacking of aromatic groups. [15-17] In self-assembled 2D structures composed of aromatic amphiphiles, the rigid aromatic segments surrounded by hydrophilic flexible chains can form relatively stable noncovalent interactions in a preferred direction. [18] Besides, the packing arrangements of aromatic segments can reversibly transform into a different equilibrium state when subjected to subtle environmental changes, demonstrating a distinct adaptive capability of dynamic shape alterations. [19] Therefore, the supramolecular 2D materials formed by aromatic amphiphiles hold promise in biological applications because the physical and chemical properties of the supramolecular 2D structure, which are attributed to the large surface area of these materials, can enhance the detection sensitivity of target molecules and increase the molecular loading and bio-conjugation efficiency. Furthermore, the flexibility, low toxicity, dispersibility, and permeability offered by 2D materials can contribute to the development of the next generation of functional materials in biological systems. [20-25] In this regard, several types of studies have been conducted on supramolecular 2D materials with biological applicability because supramolecular systems are more convenient for the fabrication of materials with multiple functionalities for biology applications. [26-34] Herein, we summarize supramolecular 2D materials based on the corresponding aromatic amphiphiles and discuss several of their biological applications (Figure 1). We classified the strategies of self-assembly of the 2D structure as follows: direct assembly of monomers and assembly in a stepwise manner via primary structures. In the direct assembly strategy, the aromatic amphiphilic blocks are assembled into 2D structures without transition into an intermediate state, in which the monomers are directly arranged in parallel, zigzag, or hexagonal conformations through hydrophobic, hostguest, and electrostatic interactions. However, in the stepwise assembly strategy, the monomers are assembled into primary structures such as dimeric micelles and fibers in the initial state, which is followed by lateral interactions to 2D structures. Various biological systems rely on the supramolecular assembly of biomolecules through noncovalent bonds for performing sophisticated functions. In particular, cell membranes, which are 2D structures in biological systems, have various characteristics such as a large surface, flexibility, and molecule-recognition ability. Supramolecular 2D materials based on biological systems provide a novel perspective for the deve...

The various proteins and asymmetric lipid bilayers present in cell membranes form curvatures, resulting in structural transformations to generate vesicles. Fission and fusion processes between vesicles and cell membranes are reversible in living organisms. Although the transformation of a two-dimensional membrane to a three-dimensional vesicle structure is a common natural phenomenon, the lack of a detailed understanding at the molecular level limits the development of synthetic systems for functional materials. Herein, we report a supramolecular membrane system through donor–acceptor interactions using a π-deficient acceptor and π-rich donor as building blocks. The reduced electrostatic repulsion between ammonium cations and the spontaneously deprotonated neutral amino group induced anisotropic membrane curvature, resulting in membrane fission to form vesicles with a detailed understanding at the molecular level. Furthermore, the reversible transformation of vesicles to membranes upon changing the pH provides a novel synthetic system exhibiting both fission and fusion processes.

Enzymes are natural catalysts that are composed of highly ordered proteins and provide nanostructured active sites for specific reactions. The ability of enzymes to efficiently bind substrates in aqueous environments and spontaneously release products upon reaction completion has inspired the development of synthetic catalysts (enzyme mimetics) based on well-organized supramolecular nanomaterials. The amphiphilicity of these materials can be exploited to dissolve hydrophobic substrates in polar solvents and gather such substrates in the hydrophobic confined spaces of supramolecular cavities. The result is high local concentrations of substrates, which allows organic reactions to proceed in polar solvent environments. Supramolecular materials can also reversibly change their functions and structures in response to external stimuli such as temperature, solvents, and guest molecules to realize the on/off switching of supramolecular catalyst-promoted reactions. In this Perspective, we introduce supramolecular materials produced by the self-assembly of aromatic amphiphiles and discuss their applications as catalysts for various reactions in polar solvents. Furthermore, we highlight the potential of these materials and provide insights into the related next-generation catalysts.