Self-assemblies of nucleolipid supramolecular synthons show unique self-sorting and cooperative assembling process

Process Dependent Complexity in Multicomponent Gels

Mixing low molecular weight gelators (LMWGs) can be used to combine favorable properties of the individual components within a multifunctional gel. Such multicomponent systems are complex enough in themselves but the method of combining components is not commonly considered something to influence self-assembly. Herein, two multicomponent systems comprising of a naphthalene-based dipeptide hydrogelator and one of two modified naphthalene diimides (NDIs), one of which forms gels, and the other does not, are investigated. These systems are probed, examining the structures formed and their gel properties (when preparing a solution from either a mixed powder of both components or by mixing pre-formed solutions of each component) using rheology, small angle neutron scattering (SANS), and absorbance spectroscopy. It is found that by altering the method of preparation, it is can either induce self-sorting or co-assembly within the fibers formed that underpin the gel network.

Evidenced cucurbit[n]uril-based host-guest interactions using single-molecule force spectroscopy

In this work, enhanced guest-pair interactions in the cavity of cucurbit[8]uril (CB[8]) are quantitatively determined using single-molecule force spectroscopy (SMFS). Significantly, the light-driven dynamic conformational change of guest pairs leads to a rupture force switching between the connected and broken CB[8]-mediated heteroternary complexation with viologen and bis(azobenzene) derivatives. SMFS is further utilized to detect methyl viologen based on the competitive host-guest interaction toward the guest in CB[8] or CB[7]. These findings highlight the extraordinary power of SMFS in supramolecular chemistry and will contribute to the fundamental understanding of the mechanochemical behavior of host-guest interactions.

Heterocycle-modified 2'-Deoxyguanosine Nucleolipid Analogs Stabilize Guanosine Gels and Self-assemble to Form Green Fluorescent Gels

Nucleoside-lipid conjugates are very useful supramolecular building blocks to construct self-assembled architectures suited for biomedical and material applications. Such nucleoside derivatives can be further synthetically manipulated to endow additional functionalities that could augment the assembling process and impart interesting properties. Here, we report the design, synthesis and self-assembling process of multifunctional supramolecular nucleolipid synthons containing an environment-sensitive fluorescent guanine. The amphiphilic synthons are composed of an 8-(2-(benzofuran-2-yl)vinyl)-guanine core and alkyl chains attached to 3'-O and 5'-O-positions of 2'-deoxyguanosine. The 2-(benzofuran-2-yl)vinyl (BFV) moiety attached at the C8 position of the nucleobase adopted a syn conformation about the glycosidic bond, which facilitated the self-assembly process through the formation of a G-tetrad as the basic unit. While 3',5'-diacylated BFV-modified dG analog stabilized the guanosine hydrogel by hampering the crystallization process and imparted fluorescence, BFV-modified dGs containing longer alkyl chains formed a green fluorescent organogel, which transformed into a yellow fluorescent gel in the presence of a complementary non-fluorescent cytidine nucleolipid. The ability of the dG analog containing short alkyl chains to modulate the mechanical property of a gel, and interesting fluorescence properties and self-assembling behavior exhibited by the dG analogs containing long alkyl chains in response to heat and complementary base underscore the potential use of these new supramolecular synthons in material applications.

Recently Developed Carbohydrate Based Gelators and Their Applications

Carbohydrate based low molecular weight gelators have been an intense subject of study over the past decade. The self-assembling systems built from natural products have high significance as biocompatible materials and renewable resources. The versatile structures available from naturally existing monosaccharides have enriched the molecular libraries that can be used for the construction of gelators. The bottom-up strategy in designing low molecular weight gelators (LMWGs) for a variety of applications has been adopted by many researchers. Rational design, along with some serendipitous discoveries, has resulted in multiple classes of molecular gelators. This review covers the literature from 2017-2020 on monosaccharide based gelators, including common hexoses, pentoses, along with some disaccharides and their derivatives. The structure-based design and structure to gelation property relationships are reviewed first, followed by stimuli-responsive gelators. The last section focuses on the applications of the sugar based gelators, including their utilization in environmental remediation, ion sensing, catalysis, drug delivery and 3D-printing. We will also review the available LMWGs and their structure correlations to the desired properties for different applications. This review aims at elucidating the design principles and structural features that are pertinent to various applications and hope to provide certain guidelines for researchers that are working at the interface of chemistry, biochemistry, and materials science.

Using multiple self-sorting for switching functions in discrete multicomponent systems

Over years self-sorting has developed into a powerful tool in supramolecular chemistry, for instance, to promote the error-free formation of intricate multicomponent assemblies. However, in order to use the enormous potential of self-sorting for sophisticated information processing more recent developments have focused on the reversible reconfiguration of multicomponent systems driven by multiple self-sorting protocols. The present mini review will provide an overview over the latest advancements in this field with a focus on reversibly switchable functions in discrete supramolecular systems.

Multi-stimuli responsive heterotypic hydrogels based on nucleolipids show selective dye adsorption

Analogous to nucleic acids, the building blocks of nucleic acids and their derivatives are widely used to create supramolecular architectures for application mainly in the field of biomedicine. Here, we describe the construction of a multi-stimuli responsive and toxic dye adsorbing heterotypic hydrogel system formed using simple nucleoside-fatty acid conjugates. The nucleolipids are derived by coupling fatty acid chains of different lengths at the 5' position of ribothymidine and uridine. The nucleolipids in the presence of a strong base (e.g. NaOH) undergo partial hydrolysis, which triggers the self-assembly of the hydrolysed components resulting in the formation of heterotypic hydrogels. Notably, the gels are formed specifically in the presence of Na+ ions as other ions such as Li+ and K+ did not support the hydrogelation process. Systematic analysis by microscopy, NMR, single crystal and powder X-ray diffraction and rheology indicated that the deprotonated nucleolipid and fatty acid salt interdigitate and provide necessary electrostatic interactions supported by Na+ ions to set the path for the hierarchical assembly process. Notably, the hydrogels are highly sensitive to external stimuli, wherein gel-sol transition can be reversibly controlled by using temperature, pH and host-guest interaction. One of the hydrogels made of 5'-O-myristate-conjugated ribothymidine was found to selectively adsorb cationic dyes such as methylene blue and rhodamine 6G in a recyclable fashion. Taken together, the easily scalable assembly, multi-stimuli responsiveness and ability to capture and release dyes highlight the potential of our nucleolipid hydrogel system in material applications and in the treatment of dye industry wastes.

A strong CD8+ T cell-stimulating supramolecular hydrogel

The development of molecules with immune stimulatory properties is crucial for cancer immunotherapy. In this work, we combined two peptide-based molecules, tuftsin (TKPR) and Nap-GDFDFDY, to develop a novel self-assembling molecule Nap-GDFDFDYTKPR (Comp.3), which has strong CD8+ T cell stimulatory properties. Comp.3 could self-assemble into nanofibers and hydrogels, which significantly improved the stability of tuftsin against enzyme digestion. The nanofibers of Comp.3 enhanced the phagocytic activity of macrophages, promoted the maturation of DCs, and stimulated the expression of cytokines. In addition, it demonstrated an excellent anti-tumor efficacy in vivo by eliciting a strong CD8+ T immune response. Taken together, our observations revealed a powerful immune stimulating nanomaterial that is a promising compound for cancer immunotherapy.

Cytidine and ribothymidine nucleolipids synthesis, organogelation, and selective anion and metal ion responsiveness

Nucleolipids of 2′,3′-O-diacylatedribothymidine supports the organogelation by utilizing inherent self-base pairing and solvent mediated bifurcated H-bonding and hydrophobic effect. These organogels exhibits unusual Hg²⁺ mediated base pairing.