Molecular design and syntheses of glycopolymers

Glycopolymer-Based Materials: Synthesis, Properties, and Biosensing Applications

Glycopolymer materials have emerged as a significant biopolymer class that has piqued the scientific community's attention due to their potential applications. Recently, they have been found to be a unique synthetic biomaterial; glycopolymer materials have also been used for various applications, including direct therapeutic methods, medical adhesives, drug/gene delivery systems, and biosensor applications. Therefore, for the next stage of biomaterial research, it is essential to understand current breakthroughs in glycopolymer-based materials research. This review discusses the most widely utilized synthetic methodologies for glycopolymer-based materials, their properties based on structure–function interactions, and the significance of these materials in biosensing applications, among other topics. When creating glycopolymer materials, contemporary polymerization methods allow precise control over molecular weight, molecular weight distribution, chemical activity, and polymer architecture. This review concludes with a discussion of the challenges and complexities of glycopolymer-based biosensors, in addition to their potential applications in the future.

Self-Assembled Nanoparticles Based on Block-Copolymers of Poly(2-Deoxy-2-methacrylamido-d-glucose)/Poly(N-Vinyl Succinamic Acid) with Poly(O-Cholesteryl Methacrylate) for Delivery of Hydrophobic Drugs

The self-assembly of amphiphilic block-copolymers is a convenient way to obtain soft nanomaterials of different morphology and scale. In turn, the use of a biomimetic approach makes it possible to synthesize polymers with fragments similar to natural macromolecules but more resistant to biodegradation. In this study, we synthesized the novel bio-inspired amphiphilic block-copolymers consisting of poly(N-methacrylamido-d-glucose) or poly(N-vinyl succinamic acid) as a hydrophilic fragment and poly(O-cholesteryl methacrylate) as a hydrophobic fragment. Block-copolymers were synthesized by radical addition-fragmentation chain-transfer (RAFT) polymerization using dithiobenzoate or trithiocarbonate chain-transfer agent depending on the first monomer, further forming the hydrophilic block. Both homopolymers and copolymers were characterized by ¹H NMR and Fourier transform infrared spectroscopy, as well as thermogravimetric analysis. The obtained copolymers had low dispersity (1.05-1.37) and molecular weights in the range of ~13,000-32,000. The amphiphilic copolymers demonstrated enhanced thermal stability in comparison with hydrophilic precursors. According to dynamic light scattering and nanoparticle tracking analysis, the obtained amphiphilic copolymers were able to self-assemble in aqueous media into nanoparticles with a hydrodynamic diameter of approximately 200 nm. An investigation of nanoparticles by transmission electron microscopy revealed their spherical shape. The obtained nanoparticles did not demonstrate cytotoxicity against human embryonic kidney (HEK293) and bronchial epithelial (BEAS-2B) cells, and they were characterized by a low uptake by macrophages in vitro. Paclitaxel loaded into the developed polymer nanoparticles retained biological activity against lung adenocarcinoma epithelial cells (A549).

Construction of Highly Ordered Glyco-Inside Nano-Assemblies through RAFT Dispersion Polymerization of Galactose-Decorated Monomer

Glyco-assemblies derived from amphiphilic sugar-decorated block copolymers (ASBCs) have emerged prominently due to their wide application, for example, in biomedicine and as drug carriers. However, to efficiently construct these glyco-assemblies is still a challenge. Herein, we report an efficient technology for the synthesis of glyco-inside nano-assemblies by utilizing RAFT polymerization of a galactose-decorated methacrylate for polymerization-induced self-assembly (PISA). Using this approach, a series of highly ordered glyco-inside nano-assemblies containing intermediate morphologies were fabricated by adjusting the length of the hydrophobic glycoblock and the polymerization solids content. A specific morphology of complex vesicles was captured during the PISA process and the formation mechanism is explained by the morphology of its precursor and intermediate. Thus, this method establishes a powerful route to fabricate glyco-assemblies with tunable morphologies and variable sizes, which is significant to enable the large-scale fabrication and wide application of glyco-assemblies.

Synthesis and Biopharmaceutical Applications of Sugar-Based Polymers: New Advances and Future Prospects

The rapid rise in research interest in carbohydrate-based polymers is undoubtedly due to the nontoxic nature of such materials in an in vivo environment and the versatile roles that the polymers can play in cellular functions. Such polymers have served as therapeutic tools for drug delivery, including antigens, proteins, and genes, as well as diagnostic devices. Our focus in the first half of this Review is on synthetic methods based on ring-opening polymerization and enzyme-catalyzed polymerization, along with controlled radical polymerization. In the second half of this Review, sugar-based polymers are discussed on the basis of their remarkable success in competitive receptor binding, as multifunctional nanocarriers of targeting inhibitors for cancer treatment, in genome-editing delivery, in immunotherapy based on endogenous antibody recruitment, and in treatment of respiratory diseases, including influenza A. Particular emphasis is put on the synthesis and biopharmaceutical applications of sugar-based polymers published in the most recent 5 years. A noticeable attribute of carbohydrate-based polymers is that the sugar-receptor interactions can be facilitated by the cooperative effect of multiple sugar units. Their diversified topology and structures will drive the development of new synthetic strategies and bring about important applications, including coronavirus-related drug therapy.

Recycling of organic fraction of municipal solid waste as an innovative precursor for the production of bio-based epoxy monomers

This paper reports the preparation of newly synthesized bio-epoxy monomers, suitable for replacing petrochemical-derived epoxy resins. An original green method able to produce epoxy monomers starting from neat carbohydrates, waste flours, and even from the organic fraction of municipal solid waste (OFMSW), was here proposed. Hence, for the first time, the epoxidation of carbohydrates was attained only through the exposition to UV and ozone radiation, without using any organic solvent to carry out the reaction. Besides the innovation in the epoxidation method, this work explored the possibility of valorizing waste materials, by recycling carbohydrate scraps; in particular, the exposition of waste flours and municipal solid waste to UV and ozone and their consequent epoxidation allowed obtaining green precursors for the production of a bio-based epoxy resin. Applicability and suitability of the synthesized compounds for epoxy monomers were investigated by curing experiments with a selected amount of a model cycloaliphatic amine-type hardener, i.e. isophorodiamine (IPDA).

Chemo-enzymatic synthesis of glycolipids, their polymerization and self-assembly

This paper describes the synthesis of bio-based methacrylated 12-hydroxystearate glucose (MASG), and its (co)polymerization with methyl methacrylate (MMA) by either free- or RAFT radical polymerizations.

Uniform and Easy-To-Prepare Glycopolymer-Brush Interface for Rapid Protein (Anti-)Adhesion Sensing

Glycopolymers have emerged as powerful and versatile glycan analogues for the investigation of cellular signal transduction. In this study, a layer of the glycopolymer-brush (GlyB) interface was functionalized on the surface of gold substrates. In order to enhance the capability and accessibility of this transducer interface, a combined protocol of copper(0)-mediated living radical polymerization (Cu(0)-LRP) with subsequent "CuAAC" click reaction was utilized to synthesize a set of novel glycopolymer precursors with a tunable scaffold structure and pyranose ligands. The resulting glycopolymer exhibited a fine-tuned molecular weight with a minor dispersity of 1.27. Through surface plasmon resonance (SPR) analysis, various GlyB interfaces exhibiting different saccharide moieties (glucose, mannose, and galactose) were examined to study their adhesion or antiadhesion potential toward three types of proteins, concanavalin A, bovine serum albumin, and peanut agglutinin (PNA). The strong affinity between poly(galactose) and PNA was further employed to construct a proof-of-concept aggregation-mediated sensing system. This minimal naked-eye sensor that consisted of only two substances, namely, gold nanoparticles and glycopolymers, was characterized and tested for its potential in protein quantification.

Copolymers containing carbohydrates and other biomolecules: design, synthesis and applications

This review highlights recent progress in random and block copolymers containing sugar and other biocompounds, including their design, synthesis, properties and selected applications.

Synthesis of well-defined glycopolymers with highly ordered sugar units in the side chain via combining CuAAC reaction and ROMP: lectin interaction study in homo- and hetero-glycopolymers

The design of novel heterogeneous glycopolymers with different sugar motifs is of critical importance in the glycopolymer field.

Polymerization induced self-assembly: an opportunity toward the self-assembly of polysaccharide-containing copolymers into high-order morphologies

Self-assembly of polysaccharide-containing amphiphilic copolymers: polymerization induced self-assembly versus traditional techniques.

Biologically Active Branched Polysaccharide Mimetics: Synthesis via Ring-Opening Polymerization of a Maltose-Based β-Lactam

Stereoregular poly-amido-saccharides bearing α-glucopyranose branches (Mal-PASs) are synthesized by anionic ring-opening polymerization of a maltose-based β-lactam monomer followed by debenzylation. The polymerization affords high molecular weight polymers (up to 31500 g/mol) with narrow dispersities (Đ < 1.1). Deprotected Mal-PASs are highly soluble in water and adopt a left-handed helical conformation in solution. Turbidimetric assay shows that Mal-PASs are multivalent ligands to lectin Concanavalin A.

Aggrecan-like biomimetic proteoglycans (BPGs) composed of natural chondroitin sulfate bristles grafted onto a poly(acrylic acid) core for molecular engineering of the extracellular matrix

Biomimetic proteoglycans (BPGs) were designed to mimic the three-dimensional (3D) bottlebrush architecture of natural extracellular matrix (ECM) proteoglycans, such as aggrecan. BPGs were synthesized by grafting native chondroitin sulfate bristles onto a synthetic poly(acrylic acid) core to form BPGs at a molecular weight of approximately ∼1.6 MDa. The aggrecan mimics were characterized chemically, physically, and structurally, confirming the 3D bottlebrush architecture as well as a level of water uptake, which is greater than that of the natural proteoglycan, aggrecan. Aggrecan mimics were cytocompatible at physiological concentrations. Fluorescently labeled BPGs were injected into the nucleus pulposus of the intervertebral disc ex vivo and were retained in tissue before and after static loading and equilibrium conditioning. BPGs infiltrated the tissue, distributed and integrated with the ECM on a molecular scale, in the absence of a bolus, thus demonstrating a new molecular approach to tissue repair: molecular matrix engineering. Molecular matrix engineering may compliment or offer an acellular alternative to current regenerative medicine strategies.

STATEMENT OF SIGNIFICANCE

Aggrecan is a natural biomolecule that is essential for connective tissue hydration and mechanics. Aggrecan is composed of negatively charged chondroitin sulfate bristles attached to a protein core in a bottlebrush configuration. With age and degeneration, enzymatic degradation of aggrecan outpaces cellular synthesis resulting in a loss of this important molecule. We demonstrate a novel biomimetic molecule composed of natural chondroitin sulfate bristles grafted onto an enzymatically-resistant synthetic core. Our molecule mimics a 3D architecture and charge density of the natural aggrecan, can be delivered via a simple injection and is retained in tissue after equilibrium conditioning and loading. This novel material can serve as a platform for molecular repair, drug delivery and tissue engineering in regenerative medicine approaches.

Polymers from sugars and CS2: synthesis and ring-opening polymerisation of sulfur-containing monomers derived from 2-deoxy-d-ribose and d-xylose

Cyclic thionocarbonate and xanthate monomers were synthesised directly from ribose- and xylose-derived diols and CS₂, and yielded novel sugar-based polymers with regioregular sulfur-containing linkages.

One-Pot Multicomponent Synthesis of Glycopolymers through a Combination of Host-Guest Interaction, Thiol-ene, and Copper-Catalyzed Click Reaction in Water

There is a common phenomenon that the heterogeneity of natural oligosaccharides contains various sugar units, which can be used to enhance affinity and selectivity toward a specific receptor, so the synthesis of heterogeneous glycopolymers is always an important issue in the glycopolymer field. Herein, this study conducts a one-pot method to prepare polyrotaxane-based heteroglycopolymers anchored with different sugar units and fluorescent moieties via the combination of host-guest interaction, thiol-ene, and copper-catalyzed click chemistry in water. Fourier transform infrared spectroscopy, nuclear magnetic resonance spectroscopy, gel permeation chromatography, X-ray diffraction, and Ellman's assay test are used in the paper to characterize the compounds. Quartz crystal microbalance-dissipation (QCD-D) experiments and bacterial adhesion assay are utilized to study the interactions of polyrotaxane-based heteroglycopolymers with Con A and Escherichia coli. The results reveal that polyrotaxanes (PRs) with mannose and glucose present better specificity toward Con A and E. coli than PRs with glucose due to synergistic effects.

Polymers from sugars: cyclic monomer synthesis, ring-opening polymerisation, material properties and applications

This feature article gives an overview of sugar-based polymers that can be made by ring-opening-polymerisation and their applications.

ADMET polymerization of α,ω-unsaturated glycolipids: synthesis and physico-chemical properties of the resulting polymers

Trehalose diesters exhibiting α,ω-unsaturation are glycolipids which can be easily polymerized by ADMET (acyclic diene metathesis) polymerization.

Synthesis of lipo-glycopolymers for cell surface engineering

A novel synthetic lipo-glycopolymer was inserted into cell membranes for cell surface engineering.

The synthesis and ring-opening metathesis polymerization of glycomonomers

The synthesis of a series of short poly(norbornene)s displaying pendant disaccharides is reported.

Synthesis of Chain-End Functionalized Glycopolymers via Cyanoxyl-Mediated Free Radical Polymerization (CMFRP)

Glycopolymers are often used as glyco-macroligands for biological research and biomedical applications in carbohydrate recognitions. Chain-end functionalized glycopolymers show more potential for practical applications, such as protein modification and solid-phase bioassays. In particular, the chain-end group allows for direct one-to-one attachment or facilitates site-specific and oriented immobilization onto solid surfaces. A series of derivatized arylamine initiators are used to generate chain-end functionalized glycopolymers by cyanoxyl-mediated free radical polymerization (CMFRP). Important features of this strategy include the capacity to produce polymers of low polydispersity (PDI <1.5) under aqueous conditions using unprotected monomers bearing a wide range of functional groups. In addition, it provides a one-pot method to synthesize α,ω-telechelic glycopolymers with derivatized arylamine at one site and O-cyanate at the other site. In the process, the capacity to orthogonally label glycopolymers or otherwise conjugate them to proteins and other molecules is greatly enhanced.

Preparation and UCST-type phase behavior of glycopolypeptides in alcoholic solvents

Glycopolypeptides with mannose pendants exhibited a reversible UCST-type phase behavior in various alcoholic solvents. The solution phase transition temperature was related to the solvent, concentration, main-chain length, and side-chain composition.

Aqueous RAFT synthesis of block and statistical copolymers of 2-(α-d-mannopyranosyloxy)ethyl methacrylate with 2-(N,N-dimethylamino)ethyl methacrylate and their application for nonviral gene delivery

Statistical and block glycopolymers presenting d-mannose were prepared by aqueous RAFT polymerization, and the effect of the microstructure on gene delivery was examined.

Post-polymerization modification of poly(L-glutamic acid) with D-(+)-glucosamine

Carboxyl functional groups of poly(L-glutamic acid) (PGlu) were modified with a D-(+)-glucosamine (GlcN) by amidation using 4-(4,6-dimethoxy-1,3,5-triazin-2-yl)-4-methylmorpholinium chloride (DMTMM) as a coupling reagent. The coupling reaction was performed in aqueous medium without protection of hydroxyl functional groups of D-(+)-glucosamine. Poly(L-glutamic acid) and GlcN functionalized polyglutamates (P(Glu-GlcN)) were thoroughly characterized by 1D and 2D NMR spectroscopy and SEC-MALS to gain detailed information on their structure, composition and molar mass characteristics. The results reveal successful functionalization with GlcN through the amide bond and also to a minor extent through ester bond formation in position 1 of GlcN. In addition, a ratio between the α- and β-form of glucosamine substituent coupled to polyglutamate repeating units as well as the content of residual dimethoxy triazinyl active ester moiety in the samples were evaluated.

Multivalent polymers for drug delivery and imaging: the challenges of conjugation

Multivalent polymers offer a powerful opportunity to develop theranostic materials on the size scale of proteins that can provide targeting, imaging, and therapeutic functionality. Achieving this goal requires the presence of multiple targeting molecules, dyes, and/or drugs on the polymer scaffold. This critical review examines the synthetic, analytical, and functional challenges associated with the heterogeneity introduced by conjugation reactions as well as polymer scaffold design. First, approaches to making multivalent polymer conjugations are discussed followed by an analysis of materials that have shown particular promise biologically. Challenges in characterizing the mixed ligand distributions and the impact of these distributions on biological applications are then discussed. Where possible, molecular-level interpretations are provided for the structures that give rise to the functional ligand and molecular weight distributions present in the polymer scaffolds. Lastly, recent strategies employed for overcoming or minimizing the presence of ligand distributions are discussed. This review focuses on multivalent polymer scaffolds where average stoichiometry and/or the distribution of products have been characterized by at least one experimental technique. Key illustrative examples are provided for scaffolds that have been carried forward to in vitro and in vivo testing with significant biological results.

Self-assembly of maltoheptaose-block-polystyrene into micellar nanoparticles and encapsulation of gold nanoparticles

The present paper discusses the controlled self-assembly of sugar-containing block copolymer, maltoheptaose-block-polystyrene (MH(1.2k)-b-PS(4.5k)), into micellar nanoparticles of ca. 30 nm radius in aqueous media and their possibility of gold encapsulation. Micellar association of MH(1.2k)-b-PS(4.5k) into nanoparticles was demonstrated by mixing a large amount of water (MH-selective solvent) with a solution of MH(1.2k)-b-PS(4.5k) in a mixture of tetrahydrofuran (THF) (PS-selective solvent) and water with a certain weight fraction [4:1 (w/w) THF/water], where MH(1.2k)-b-PS(4.5k) exists as well-swollen single chains, followed by evaporation of THF. The mean hydrodynamic radii (Rh) of the nanoparticles were determined by dynamic light scattering (DLS) to be ca. 30 and 80 nm depending upon the method of preparation. The resulting nanoparticles were clearly visualized by transmission electron microscopy (TEM), atomic force microscopy (AFM), and field emission gun-scanning electron microscopy (FEG-SEM) imaging and complemented by nanoparticle tracking analysis (NTA) using a NanoSight instrument. The preliminary study of the self-assembly of MH(1.2k)-b-PS(4.5k) in the presence of gold nanoparticles functionalized with PS chains grafted on their surface indicated potential possibilities of encapsulation of gold nanoparticles into the block copolymer nanoparticles in aqueous media.