Multiple C-H⋯anion and N-H⋯anion hydrogen bond directed two-dimensional crystalline nanosheets with precise distance control of surface charges for enhanced DNA capture.

Utilizing combined non-covalent interactions and introducing anions as structure-directing factors to build oriented self-assembly and 2D crystalline nanosheet superstructures with precise distance control of surface charges in competitive aqueous solvents still represents a formidable challenge for supramolecular chemists. Here we report a simple, efficient, and general strategy for multiple C-H/N-H⋯anion hydrogen bond enhanced π-π interaction directed 2D oriented self-assembly in water, which is based on the head-to-tail association of perylene monoimide dimers (PMIs) by directing N-H⋯anion interactions to position the anions to the C-H of π systems (PMIs). Interesting, this behavior only occurs for size-matched anions (Cl- to NO3-; <45 Å3), while larger anions could not form 2D crystalline nanosheet superstructures. The results show that crystalline nanosheet superstructures with precise distance control of surface charges can effectively capture DNA, possibly due to their high surface charge density and the distance match between the distance of surface charges and the distance between adjacent base pairs.

Spatiotemporal Control over Chemical Assembly in Living Cells by Integration of Acid-Catalyzed Hydrolysis and Enzymatic Reactions.

Spatiotemporal control of chemical assembly in living cells remains challenging. We have now developed an efficient and general platform to precisely control the formation of assemblies in living cells. We introduced an O-[bis(dimethylamino)phosphono]tyrosine protection strategy in the self-assembly motif as the Trojan horse, whereby the programmed precursors resist hydrolysis by phosphatases on and inside cells because the unmasking of the enzymatic cleavage site occurs selectively in the acidic environment of lysosomes. After demonstrating the multistage self-assembly processes in vitro by liquid chromatography/mass spectrometry (LC-MS), cryogenic electron microscopy (Cryo-EM), and circular dichroism (CD), we investigated the formation of site-specific self-assembly in living cells using confocal laser scanning microscopy (CLSM), LC-MS, and biological electron microscopy (Bio-EM). Controlling chemical assembly in living systems spatiotemporally may have applications in supramolecular chemistry, materials science, synthetic biology, and chemical biology.

A Carbon Dioxide Bubble-Induced Vortex Triggers Co-Assembly of Nanotubes with Controlled Chirality.

It is challenging to prepare co-organized nanotube systems with controlled nanoscale chirality in an aqueous liquid flow field. Such systems are responsive to a bubbled external gas. A liquid vortex induced by bubbling carbon dioxide (CO2 ) gas was used to stimulate the formation of nanotubes with controlled chirality; two kinds of achiral cationic building blocks were co-assembled in aqueous solution. CO2 -triggered nanotube formation occurs by formation of metastable intermediate structures (short helical ribbons and short tubules) and by transition from short tubules to long tubules in response to chirality matching self-assembly. Interestingly, the chirality sign of these assemblies can be selected for by the circulation direction of the CO2 bubble-induced vortex during the co-assembly process.

Biomimetic Heterodimerization of Tetrapeptides to Generate Liquid Crystalline Hydrogel in A Two-Component System.

Anisotropic structures made by hierarchical self-assembly and crystallization play an essential role in the living system. However, the spontaneous formation of liquid crystalline hydrogel of low molecular weight organic molecules with controlled properties remains challenging. This work describes a rational design of tetrapeptide without N-terminal modification and chemical conjugation that utilizes intermolecular interactions to drive the formation of nanofiber bundles in a two-component system, which could not be accessed by a single component. The diameter of nanofibers can be simply controlled by varying the enantiomer of electrostatic pairs. Mutation of lysine (K) to arginine (R) results in an over 30-fold increase of mechanical property. Mechanistic studies using different techniques unravel the mechanism of self-assembly and formation of anisotropic liquid crystalline domains. All-atom molecular dynamics simulations reveal that the mixture of heterochiral peptides self-assembles into a nanofiber with a larger width compared to the homochiral assemblies due to the different stacking pattern and intermolecular interactions. The intermolecular interactions show an obvious increase by substituting the K with R, facilitating a more stable assembly and further altering the assembly mechanics and bulk material properties. Moreover, we also demonstrated that the hydrogel properties can be easily controlled by incorporating a light-responsive group. This work provides a method to generate the liquid crystalline hydrogel from isotropic monomers.

Co-assembled nanotubes with controlled curvature radius using a hydrogen bond regulation strategy.

The design of co-organized nanotube systems with controlled curvature radius that are realized by tilt modulation of co-assembled molecules, induced by the strength of non-covalent interactions in aqueous media, remains a significant challenge. Here, we report success in utilizing a hydrogen bond regulation strategy to stimulate molecular tilt for the formation of nanotubes with controlled curvature radius based on the co-assembly of two kinds of achiral cationic building blocks in aqueous solution. Computations and electron microscopy experiments suggest that the nanotube curvature radius drastically decreases as the tilt angle θ of co-assembled molecules increases with an increase of hydrogen bond strength. Interestingly, a slight change in the co-assembled molecular tilt causes a drastic change in the nanotube curvature radius.