Fluorescent Conjugated Polyfluorene with Pendant Lactopyranosyl Ligands for Studies of Ca2+-Mediated Carbohydrate−Carbohydrate Interaction

Detailed Study of the Interactions between Glycopolymers in the Presence of Metal Ions through Quartz Crystal Microbalance Method

Polymer self-assemblies driven by enthalpic interactions, such as hydrogen bonding and electrostatic interactions, exhibit distinct properties compared to those driven by hydrophobic interactions. Carbohydrate-carbohydrate interactions, which are observed in physiological phenomena, also fall under enthalpic interactions. Our group previously reported on self-assemblies of methacrylate-type glycopolymers carrying mannose units in the presence of calcium ions; however, a detailed study of these interactions was lacking. In this work, we investigated the interactions between glycopolymers using the quartz crystal microbalance (QCM) method. Our quantitative analysis revealed that the interactions between the glycopolymers were influenced by the carbohydrate structures in the side chains, the types of divalent metal ions, and the structures of the polymer main chains. Notably, the strongest interaction was observed in the combination of methacrylate-type glycopolymers carrying mannose units and calcium ions, demonstrating their potential as a driving force for polymer self-assembly.

Cu(I)-Catalyzed Click Chemistry in Glycoscience and Their Diverse Applications

Copper(I)-catalyzed 1,3-dipolar cycloaddition between organic azides and terminal alkynes, commonly known as CuAAC or click chemistry, has been identified as one of the most successful, versatile, reliable, and modular strategies for the rapid and regioselective construction of 1,4-disubstituted 1,2,3-triazoles as diversely functionalized molecules. Carbohydrates, an integral part of living cells, have several fascinating features, including their structural diversity, biocompatibility, bioavailability, hydrophilicity, and superior ADME properties with minimal toxicity, which support increased demand to explore them as versatile scaffolds for easy access to diverse glycohybrids and well-defined glycoconjugates for complete chemical, biochemical, and pharmacological investigations. This review highlights the successful development of CuAAC or click chemistry in emerging areas of glycoscience, including the synthesis of triazole appended carbohydrate-containing molecular architectures (mainly glycohybrids, glycoconjugates, glycopolymers, glycopeptides, glycoproteins, glycolipids, glycoclusters, and glycodendrimers through regioselective triazole forming modular and bio-orthogonal coupling protocols). It discusses the widespread applications of these glycoproducts as enzyme inhibitors in drug discovery and development, sensing, gelation, chelation, glycosylation, and catalysis. This review also covers the impact of click chemistry and provides future perspectives on its role in various emerging disciplines of science and technology.

Probing the glycopolymer–ion interaction via specific ion effects

Specific ion effects were used to probe the interactions between thermoresponsive glycopolymers and different ions.

Self-assembly of bacteria cellulose hydrogels carrying multiple carbohydrate appendages to visualize carbohydrate-carbohydrate interactions

Nata de coco was chemically modified to afford the bacterial cellulose hydrogels carrying terminal alkynes. The resultant hydrogels were then converted into hydrogels carrying lactosides or those carrying α-2,3-sialyllactosides by the Cu⁺-catalyzed alkyne-azide cyclization. The stable homo association of the hydrogels carrying lactosides was observed in an aqueous solution containing Ca²⁺, thereby demonstrating the Ca²⁺-mediated lactoside-lactoside interactions. Ca²⁺ also stabilized the hetero associations among the hydrogels carrying lactosides and those carrying α-2,3-sialyllactosides, thereby also demonstrating the Ca²⁺-induced interactions between the lactosides and the α-2,3-sialyllactosides. The sizes of these hydrogels were of the order of ca. 5 mm, and their associations could thus be readily monitored with the naked eye.

Synthesis of water-soluble fluorescent polymeric glycoconjugate for the detection of cholera toxin

Considering inherence optical properties of adjoint polyfluorenes and special functions of water-soluble conjugated glycopolymers, a triazole chain glycoconjugate via one-pot method were rapidly synthesized to prepare a lactate ligand polyfluorene with a clear fluorescent label by a nickel-catalyzed Yamamoto coupling polymerization. The water solubility and biocompatibility of the glycoconjugated polymer were ameliorated when the lactose group introduced as the side chain of the conjugated polymer. As a fluorescent multivalent system of glycoconjugates containing pyranogalactose groups, the interaction between pyranogalactose group and cholera toxin B subunit was studied by fluorescence spectrophotometric titration. PF-Lac has a broad application prospect in the check of cholera toxin and the study of glycoprotein interaction.

Synthesis of Glycosylated Metal Complexes for Probing Carbohydrate-Carbohydrate Interactions

Densely packed carbohydrate clusters on cell surfaces play essential roles in varieties of bioprocesses. Little information has been, however, accumulated so far concerning their structural/functional details. In this chapter, we discuss artificial systems to investigate carbohydrate-carbohydrate interactions within/between the carbohydrate cluster(s). Among such artificial systems, much attention will be especially placed on glycosylated tris-bipyridine ferrous complexes for monitoring not only carbohydrate-carbohydrate interactions within the glycocluster but also their resultant conformational changes.

Synthesis and conformational analysis of poly(phenylacetylene)s with serinol-tethered carbohydrate appendages

We synthesized phenylacetylenes containing β-lactoside, β-cellobioside, or β-maltoside, and polymerized them to produce the corresponding poly (phenylacetylene)s. In these poly (phenylacetylene)s, the pendent carbohydrates were tethered to the mainchains by serinol spacers. Because similar glycosyl serinol units are found in the natural glycosphingolipids in cell membranes, the densely packed carbohydrate clusters along the poly (phenylacetylene) mainchains act as molecular mimics of cell surface glycoclusters. We analyzed the conformation of the glycosylated poly (phenylacetylene)s using circular dichroism spectroscopy, and found that the spatial carbohydrate packing within the glycoclusters changed on the addition of salts.

Cu-Catalyzed Click Reaction in Carbohydrate Chemistry

Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition (CuAAC), popularly known as the "click reaction", serves as the most potent and highly dependable tool for facile construction of simple to complex architectures at the molecular level. Click-knitted threads of two exclusively different molecular entities have created some really interesting structures for more than 15 years with a broad spectrum of applicability, including in the fascinating fields of synthetic chemistry, medicinal science, biochemistry, pharmacology, material science, and catalysis. The unique properties of the carbohydrate moiety and the advantages of highly chemo- and regioselective click chemistry, such as mild reaction conditions, efficient performance with a wide range of solvents, and compatibility with different functionalities, together produce miraculous neoglycoconjugates and neoglycopolymers with various synthetic, biological, and pharmaceutical applications. In this review we highlight the successful advancement of Cu(I)-catalyzed click chemistry in glycoscience and its applications as well as future scope in different streams of applied sciences.

A hydroxyl-functionalized microporous organic polymer for capture and catalytic conversion of CO2

A novel hydroxyl-functionalized microporous organic polymer (HF-MOP) exhibited good CO₂ capture performance and excellent catalytic activity in cycloaddition reaction.

Sugar-functionalized triptycenes used for dispersion of single-walled carbon nanotubes in aqueous solution by supramolecular interaction

Two water-soluble sugar-functionalized triptycene derivatives were synthesized and used for dispersion of SWCNTs in aqueous solution via supramolecular interaction.

Glycoconjugated amphiphilic polymers via click-chemistry for the encapsulation of quantum dots

Herein, we present a strategy for the glycoconjugation of nanoparticles (NPs), with a special focus on fluorescent quantum dots (QDs), recently described by us as "preassembly" approach. Therein, prior to the encapsulation of diverse nanoparticles by an amphiphilic poly(isoprene)-b-poly(ethylene glycol) diblock copolymer (PI-b-PEG), the terminal PEG appendage was modified by covalently attaching a carbohydrate moiety using Huisgen-type click-chemistry. Successful functionalization was proven by NMR spectroscopy. The terminally glycoconjugated polymers were subsequently used for the encapsulation of QDs in a phase transfer process, which fully preserved fluorescence properties. Binding of these nanoconstructs to the lectin Concanavalin A (Con A) was studied via surface plasmon resonance (SPR). Depending on the carbohydrate moiety, namely, D-manno-heptulose, D-glucose, D-galactose, 2-deoxy-2-{[methylamino)carbonyl]amino}-D-glucopyranose ("des(nitroso)-streptozotocin"), or D-maltose, the glycoconjugated QDs showed enhanced affinity constants due to multivalent binding effects. None of the constructs showed toxicity from 0.001 to 1 μM (particle concentration) using standard WST and LDH assays on A549 cells.

Fluorinated Porous Organic Polymers via Direct C-H Arylation Polycondensation

Considering the high reactivity of the C-H bonds in fluorobenzenes for direct arylation and special properties of fluorinated polymers, herein, synthesis of fluorinated porous organic polymers via direct C-H arylation polycondensation is explored. The obtained polymers (FPOP-1 and FPOP-2) are well characterized and show high porosities with Brunauer-Emmett-Teller specific surface area of above 1000 m² g^-1. Different pore size distribution (PSD) profiles of porous polymers can be obtained by selecting different core constructing monomers. FPOP-2 exhibits a relatively narrower PSD with the dominant pore size at about 0.63 nm, which is more suitable for adsorption of small gas molecules (H₂, CO₂, and CH₄) than FPOP-1. As a porous fluorinated hydrophobic material, FPOP-2 possesses high adsorption ability for toluene (976 mg g^-1 at saturated vapor pressure and room temperature) due to its high porosities and binding affinities between the guest molecules and the host network. The good sorption capacity of FPOP-2 for toluene makes it show potential applications in elimination of harmful small aromatic molecules in the environment.

Stabilization of neutral polyfluorene in aqueous solution through their interaction with phospholipids and sol-gel encapsulation

Interaction between poly[9,9-bis(6'-bromohexyl)-2,7-fluorene-co-alt-1,4-phenylene] (PFPBr2), a neutral conjugated polyfluorene which is completely insoluble in water, and zwitterionic phospholipids has been investigated in order to generate new fluorescent structures which are stable in aqueous media as a means of extending the biological applications of these kinds of polymers. Two types of differently shaped and composed fluorescent structures were identified and then isolated and characterized separately using different biophysical techniques. The first structure type, corresponding to liposomal complexes, showed a fluorescence band centered around 405 nm and maximum absorption at 345 nm, while the second, corresponding to polymer-phospholipid aggregates of variable sizes with lower lipid content, absorbed at longer wavelengths and displayed a well resolved fluorescence spectrum with a maximum centered at 424 nm. Both structures were stable in a large range of pH, and their fluorescence intensity remained practically unaltered for 10 days; it then began to decrease, which was probably because of aggregation. Encapsulation of these structures within the pores of a sol-gel matrix did not affect their fluorescent properties but increased their stability, avoiding further aggregation and subsequent precipitation.

Supramolecular self-assembly induced graphene oxide based hydrogels and organogels

We demonstrate the construction of three-dimensional graphene oxide based gel networks through the self-assembly of a series of amphiphilic molecules, which possess a polar carbohydrate headgroup attached to a nonpolar pyrene group. The gelation process can occur in both aqueous and organic solutions and be influenced by the gelators' molecular structure. The driving forces for the gelation process were determined as π-π stacking and hydrogen bonding interaction by using fluorescence and infrared spectroscopies. Rheometry was used to investigate the mechanical properties of the hydrogels and the organogels. The hydrogel was investigated to be applied to remove dye from aqueous solution.

Fluorescent nanoparticles based on self-assembled pi-conjugated systems

pi-Conjugated molecules are interesting components to prepare fluorescent nanoparticles. From the use of polymer chains that form small aggregates in water to the self-assembly of small chromophoric segments into highly ordered structures, the preparation of these materials allows to develop systems with applications as sensors or biolabels. The potential functionalization of the nanoparticles can lead to specific probing. This progress report describes the recent advances in the preparation of such emittive organic nanoparticles.