Creation of unique supramolecular nanoarchitectures utilizing natural polysaccharide as a one-dimensional host

Methods of study on conformation of polysaccharides from natural products: A review

Polysaccharides from natural products play multiple roles and have extensive bioactivities in life process. Bioactivities of polysaccharides (e.g., Lentinan, Schizophyllan, Scleroglucan, Curdlan, Cinerean) have a close relation to their chain conformation. Compared to other types of polysaccharides, the conformation of β-glucan has been studied more. The major research methods of conformation of polysaccharides from natural products (Congo red experiment, circular dichroism spectrum, viscosity method, light scattering method, size exclusion chromatography, atomic force microscope), corresponding experimental schemes, and the external factors affecting polysaccharide conformation were reviewed in this paper. These research methods of conformation have been widely used, among which Congo red experiment and viscosity method are the most convenient ones to study the morphological changes of polysaccharide chains.

Recent Advances in Chain Conformation and Bioactivities of Triple-Helix Polysaccharides

Natural polysaccharides derived from renewable biomass sources are regarded as environmentally friendly and sustainable polymers. As the third most abundant biomacromolecule in nature, after proteins and nucleic acids, polysaccharides are also closely related with many different life activities. In particular, β-glucans are one of the most widely reported bioactive polysaccharides and are usually considered as biological response modifiers. Among them, β-glucans with triple-helix conformation have been the hottest and most well-researched polysaccharides at present, especially lentinan and schizophyllan, which are clinically used as cancer therapies in some Asian countries. Thus, creation of these active triple-helix polysaccharides is beneficial to the research and development of sustainable "green" biopolymers in the fields of food and life sciences. Therefore, full fundamental research of triple-helix polysaccharides is essential to discover more applications for polysaccharides. In this Review, the recent research progress of chain conformations, bioactivities, and structure-function relationships of triple-helix β-glucans is summarized. The main contents include the characterization methods of the macromolecular conformation, proof of triple helices, bioactivities, and structure-function relationships. We believe that the governments, enterprises, universities, and institutes dealing with the survival and health of human beings can expect the development of natural bioproducts in the future. Hence, a deep understanding of β-glucans with triple-helix chain conformation is necessary for application of natural medicines and biologics for a sustainable world.

Supramolecular Nanotube Reactors for Production of Imine Polymers with Controlled Conformation, Size, and Chirality

A series of supramolecular nanotubes with inner diameters of 1, 4, 9, 12, 16, and 29 nm are prepared from amino acid lipids. The hydrophobic channels of the nanotubes act as reactors for the formation of imine polymers by not only effectively encapsulating the benzaldehyde and diacetyleneamine precursors of the imine monomers but also markedly accelerating imine formation. The nanotube inner diameter determines whether the imine monomers self-assemble into nanoparticles, nanotapes, nanocoils, or twisted nanofibers in the channels. UV-induced polymerization of the diacetylene units in the imine nanostructures followed by decomposition of the nanotubes into molecular dispersions of the constituent amino acid lipids results in expulsion of the polymerized imine nanostructures with retained conformation. The isolated nanocoils and twisted nanofibers retain the helicity and circular dichroism induced by the nanotubes, which exhibits supramolecular chirality, even though the components of the imine monomers are achiral. These supramolecular nanotubes with tunable diameters and functionalizable surfaces can be expected to be useful for the production of polymers with controlled conformation, size, and chirality without the need for rational design or chemical modification of the monomers or optimization of the polymerization conditions.

Thermoresponsive PEG-Coated Nanotubes as Chiral Selectors of Amino Acids and Peptides

A series of nanotubes with a dense layer of short poly(ethylene glycol) (PEG) chains on the inner surface are prepared by means of a coassembly process using glycolipids and PEG derivatives. Dehydration of the PEG chains by heating increases the hydrophobicity of the nanotube channel and fluorescent-dye-labeled amino acids are extracted from bulk solution. Rehydration of the PEG chains by cooling results in back-extraction of the amino acids into the bulk solution. Because of the supramolecular chirality of the nanotubes, amino acid enantiomers can be separated in the back-extraction procedure, which is detectable with the naked eye as a change in fluorescence as the amino acids are released from the nanotubes. The efficiency and selectivity of the chiral separation are enhanced by tuning the chemical features and inner diameter of the nanotube channels. For example, compared with wide nanotube channels (8 nm), narrow nanotube channels (4 nm) provide more effective electrostatic attraction and hydrogen bond interaction environments for the transporting amino acids. Introduction of branched alkyl chains to the inner surface of the nanotubes enables chiral separation of peptides containing hydrophobic amino acids. The system described here provides a simple, quick, and on-site chiral separation in biological and medical fields.

Supramolecular Self-Assembly into Biofunctional Soft Nanotubes: From Bilayers to Monolayers

The inner and outer surfaces of bilayer-based lipid nanotubes can be hardly modified selectively by a favorite functional group. Monolayer-based nanotubes display a definitive difference in their inner and outer functionalities if bipolar wedge-shaped amphiphiles, so-called bolaamphiphiles, as a constituent of the monolayer membrane pack in a parallel fashion with a head-to-tail interface. To exclusively form unsymmetrical monolayer lipid membranes, we focus herein on the rational molecular design of bolaamphiphiles and a variety of self-assembly processes into tubular architectures. We first describe the importance of polymorph and polytype control and then discuss diverse methodologies utilizing a polymer template, multiple hydrogen bonds, binary and ternary coassembly, and two-step self-assembly. Novel biologically important functions of the obtained soft nanotubes, brought about only by completely unsymmetrical inner and outer surfaces, are discussed in terms of protein refolding, drug nanocarriers, lectin detection, a chiral inducer for achiral polymers, the tailored fabrication of polydopamine, and spontaneous nematic alignment.

Soft nanotubes acting as confinement effecters and chirality inducers for achiral polythiophenes

Depending on their nanochannel sizes, soft nanotubes were able to not only control the conformation and aggregation state of encapsulated achiral polythiophene boronic acids but also induce chirality in the polythiophene chains that exhibit chiral recognition abilities for d, l-sugars.