Hierarchical self-assembly of switchable nucleolipid supramolecular gels based on environmentally-sensitive fluorescent nucleoside analogs

Abstract

Exquisite recognition and folding properties have rendered nucleic acids as useful supramolecular synthons for the construction of programmable architectures. Despite their proven applications in nanotechnology, scalability and fabrication of nucleic acid nanostructures still remain a challenge. Here, we describe a novel design strategy to construct new supramolecular nucleolipid synthons by using environmentally-sensitive fluorescent nucleoside analogs, based on 5-(benzofuran-2-yl)uracil and 5-(benzo[b]thiophen-2-yl)uracil cores, as the head group and fatty acids, attached to the ribose sugar, as the lipophilic group. These modified nucleoside-lipid hybrids formed organogels driven by hierarchical structures such as fibers, twisted ribbons, helical ribbons and nanotubes, which depended on the nature of fatty acid chain and nucleobase modification. NMR, single crystal X-ray and powder X-ray diffraction studies revealed the coordinated interplay of various non-covalent interactions invoked by modified nucleobase, sugar and fatty acid chains in setting up the pathway for the gelation process. Importantly, these nucleolipid gels retained or displayed aggregation-induced enhanced emission and their gelation behavior and photophysical properties could be reversibly switched by external stimuli such as temperature, ultrasound and chemicals. Furthermore, the switchable nature of nucleolipid gels to chemical stimuli enabled the selective two channel recognition of fluoride and Hg(2+) ions through visual phase transition and fluorescence change. Fluorescent organogels exhibiting such a combination of useful features is rare, and hence, we expect that this innovative design of fluorescent nucleolipid supramolecular synthons could lead to the emergence of a new family of smart optical materials and probes.

Hydrophobicity of surface-immobilised molecules influences architectures formed via interfacial self-assembly of nucleoside-based gelators

“…S1, ESI †) were synthesised and used to prepare gel films on piranha cleaned silicon wafers (OH surfaces). This family of gelators was selected over other nucleolipid-based gelators under investigations 14,[18][19][20] as they are synthesized through a straightforward, one-pot synthetic route, 21 their mechanism of self-assembly is well-understood 17 and they have shown promising potential in drug delivery applications. 21 The OH surfaces (surfaces covered with hydrophilic hydroxyl groups) were characterized with AFM ( Fig.…”

“…as key driving forces in self-assembly. [12][13][14][15][16][17] Previously, we have shown that an alkyl-modified derivative of cytidine produces gel films with different mechanical properties on a hydrophilic and a hydrophobic surface. 11 AFM measurements showed that the dried gels displayed fibres with larger diameters on the hydrophobic than on the hydrophilic surface.…”

“Sweet” ionic liquid gels: materials for sweetening of fuels

“…49,50 Sonotropy has been much less investigated. 15,51,52 However, both abilities were recently reported for ILGs. 29,31,32,34 Our data are displayed in Table 3.…”

Lipid and Nucleic Acid Chemistries: Combining the Best of Both Worlds to Construct Advanced Biomaterials

“…The same approach was used very recently to provide NL hybrids incorporating emissive nucleosides following very classical coupling reaction conditions with a variety of lipidic chains before the Stille reaction step ( Figure A) . Fluorescent derivatives were shown to exhibit a good gelation ability in organic solvents.…”

“…B) Gel images under UV light (top, 365 nm) and gelation properties of fluorescent NLs (bottom). Reproduced with permission . Copyright 2016, Royal Society of Chemistry.…”