Synthesis of glycopolymers via click reactions

Click Chemistry in Polymersome Technology

Polymersomes, self-assembled nanoparticles composed of amphiphilic block copolymers, have emerged as promising versatile nanovesicles with various applications, such as drug delivery, medical imaging, and diagnostics. The integration of click chemistry reactions, specifically the copper [I]-catalysed azide-alkyne cycloaddition (CuAAC), has greatly expanded the functionalisation and bioconjugation capabilities of polymersomes and new drugs, being this synergistic combination explored in this review. It also provides up-to-date examples of previous incorporations of click-compatible moieties (azide and alkyne functional groups) into polymer building blocks, enabling the "click" attachment of various functional groups and ligands, delving into the diverse range of click reactions that have been reported and employed for polymersome copolymer synthesis and the modification of polymersome surfaces, including ligand conjugation and surface modification. Overall, this review explores the current state-of-the-art of the combinatory usage, in recent years, of polymersomes with the click chemistry reaction, highlighting examples of studies of their synthesis and functionalisation strategies.

Recent Advances in Polymers Bearing Activated Esters for the Synthesis of Glycopolymers by Postpolymerization Modification

Glycopolymers are functional polymers with saccharide moieties on their side chains and are attractive candidates for biomaterials. Postpolymerization modification can be employed for the synthesis of glycopolymers. Activated esters are useful in various fields, including polymer chemistry and biochemistry, because of their high reactivity and ease of reaction. In particular, the formation of amide bonds caused by the reaction of activated esters with amino groups is of high synthetic chemical value owing to its high selectivity. It has been employed in the synthesis of various functional polymers, including glycopolymers. This paper reviews the recent advances in polymers bearing activated esters for the synthesis of glycopolymers by postpolymerization modification. The development of polymers bearing hydrophobic and hydrophilic activated esters is described. Although water-soluble activated esters are generally unstable and hydrolyzed in water, novel polymer backbones bearing water-soluble activated esters are stable and useful for postpolymerization modification for synthesizing glycopolymers in water. Dual postpolymerization modification can be employed to modify polymer side chains using two different molecules. Thiolactone and glycine propargyl esters on the polymer backbone are described as activated esters for dual postpolymerization modification.

Synthesis, characterization, thermokinetic analysis and biological application of novel allyl glucosamine based glycopolymers

The synthesis of glycopolymers by copolymerising an allyl glucosamine (AG) monomer with co-monomers methyl methacrylate (MMA), acrylonitrile (AN) and 2-hydroxyethyl methacrylate (HEMA) was investigated via free-radical polymerisation of 2,2-azobisisobutyronitrile (AIBN) in dimethylformamide (DMF). Three new copolymers, poly(AG-co-MMA), poly(AG-co-AN) and poly(AG-co-HEMA), were obtained. The chemical structures of the glycopolymers were analysed using 1H-NMR, 13C-NMR and FTIR. The thermal properties and degradation kinetics of the three glycopolymers were examined by thermogravimetric (TG) analysis at different heating rates. The effects of different co-monomers on the copolymerisation yield, thermal properties and biological activities of the resulting glycopolymers were investigated. The activation energies of the decomposition stages were calculated using the Flynn-Wall-Ozawa (FWO) and Kissinger methods. Furthermore, the biological activity of AG monomers and glycopolymers was studied and compared to chitosan. Poly(AG-co-HEMA) had the most significant effect on MCF-7 cell viability, and all glycopolymers have a low toxic effect profile on MCF-7 cell lines.

Hierarchy of Complex Glycomacromolecules: From Controlled Topologies to Biomedical Applications

Carbohydrates bearing a distinct complexity use a special code (Glycocode) to communicate with carbohydrate-binding proteins at a high precision to manipulate biological activities in complex biological environments. The level of complexity in carbohydrate-containing macromolecules controls the amount and specificity of information that can be stored in biomacromolecules. Therefore, a better understanding of the glycocode is crucial to open new areas of biomedical applications by controlling or manipulating the interaction between immune cells and pathogens in terms of trafficking and signaling, which would become a powerful tool to prevent infectious diseases. Even though a certain level of progress has been achieved over the past decade, synthetic glycomacromolecules are still lagging far behind naturally existing glycans in terms of complexity and precision because of insufficient and inefficient synthetic techniques. Currently, specific targeting at a cellular level using synthetic glycomacromolecules is still challenging. It is obvious that multidisciplinary collaborations are essential between different specialized disciplines to enhance the carbohydrate receptor-targeting paradigm for new biomedical applications. In this Perspective, recent developments in the synthesis of sophisticated glycomacromolecules are highlighted, and their biological and biomedical applications are also discussed in detail.

1,6-heptadiynes based cyclopolymerization functionalized with mannose by post polymer modification for protein interaction

Carbohydrate functionalized polymers or Glycopolymers have earned a great deal of interest in recent times for their potential biomedical applications. In the present study, a mannose containing glycopolymer was synthesized by cyclopolymerization of malonic acid derivative using second generation Hoveyda Grubbs' catalyst. Post-polymerization modification was done to install a propargyl moiety. Finally, functionalization of the propargylated polymer with 2-azidoethyl mannoside using azide-alkyne "click chemistry" furnished the target glycopolymer which was successfully characterized using NMR, FT-IR, mass spectroscopy and advanced polymer chromatography. The glycopolymer was found to self-assemble into capsule and spherical shape in water and DMSO respectively and these morphologies were observed through SEM and TEM. Upon interaction with Con A, the mannose containing glycopolymer showed an increment in aggregation induced fluorescence with increasing concentration of the lectin. In vitro cytotoxicity studies on MCF 7 cell line showed 90% cell viability up to glycopolymer concentration of 500 μg/mL.

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.

Synthetic linear glycopolymers and their biological applications

As typical affinities of carbohydrates with their receptors are modest, polymers of carbohydrates (glycopolymers) are exciting tools to probe the multifaceted biological activities of glycans. In this review, the linear glycopolymers and the multivalency effects are first introduced. This is followed by discussions of methods to synthesize these polymers. Subsequently, the interactions of glycopolymers with plant lectins and viral/bacterial carbohydrate binding proteins are discussed. In addition, applications of the glycopolymers in facilitating glycan microarray studies, mimicking cell surface glycans, modulation of the immune system, cryoprotection of protein, and electron-beam lithography are presented to stimulate further development of this fascinating technology.

Polymer-Based Drug-Free Therapeutics for Anticancer, Anti-Inflammatory, and Antibacterial Treatment

This paper summarizes the area of biomedicinal polymers, which serve as nanomedicines even though they do not contain any anticancer or antiinflammatory drugs. These polymer nanomedicines with unique design are in the literature highlighted as a novel class of therapeutics called "drug-free macromolecular therapeutics." Their therapeutic efficacy is based on the tailored multiple presentations of biologically active vectors, i.e., peptides, oligopeptides, or oligosaccharides. Thus, they enable, for example, to directly induce the apoptosis of malignant cells by the crosslinking of surface slowly internalizing receptors, or to deplete the efficacy of tumor-associated proteins. The precise biorecognition of natural binding motifs by multiple vectors on the polymer construct remains the crucial part in the designing of these drug-free nanomedicines. Here, the rationales, designs, synthetic approaches, and therapeutic potential of drug-free macromolecular therapeutics consisting of various active vectors are described in detail. Recent developments and achievements for namely B-cell lymphoma treatment, Gal-3-positive tumors, inflammative liver injury, and bacterial treatment are reviewed and highlighted. Finally, a possible future prospect within this highly exciting new field of nanomedicine research is presented.

Hyaluronan (HA)-inspired glycopolymers as molecular tools for studying HA functions

Hyaluronic acid (HA), the only non-sulphated glycosaminoglycan, serves numerous structural and biological functions in the human body, from providing viscoelasticity in tissues to creating hydrated environments for cell migration and proliferation. HA is also involved in the regulation of morphogenesis, inflammation and tumorigenesis through interactions with specific HA-binding proteins. Whilst the physicochemical and biological properties of HA have been widely studied for decades, the exact mechanisms by which HA exerts its multiple functions are not completely understood. Glycopolymers offer a simple and precise synthetic platform for the preparation of glycan analogues, being an alternative to the demanding synthetic chemical glycosylation. A library of homo, statistical and alternating HA glycopolymers were synthesised by reversible addition-fragmentation chain transfer polymerisation and post-modification utilising copper alkyne-azide cycloaddition to graft orthogonal pendant HA monosaccharides (N-acetyl glucosamine: GlcNAc and glucuronic acid: GlcA) onto the polymer. Using surface plasmon resonance, the binding of the glycopolymers to known HA-binding peptides and proteins (CD44, hyaluronidase) was assessed and compared to carbohydrate-binding proteins (lectins). These studies revealed potential structure-binding relationships between HA monosaccharides and HA receptors and novel HA binders, such as Dectin-1 and DEC-205 lectins. The inhibitory effect of HA glycopolymers on hyaluronidase (HAase) activity was also investigated suggesting GlcNAc- and GlcA-based glycopolymers as potential HAase inhibitors.

Carbohydrate–lectin recognition of well-defined heterogeneous dendronized glycopolymers: systematic studies on the heterogeneity in glycopolymer–lectin binding

A platform for achieving dendronized heteroglycopolymers via gradient CuAAC click reaction and PPM was developed. Further systematic studies revealed the synergistic effect of heterogeneity plays a crucial role in glycopolymer–lectin binding.

One-pot chemoenzymatic synthesis of glycopolymers from unprotected sugars via glycosidase-catalysed glycosylation using triazinyl glycosides

Glycopolymers were successfully synthesised from unprotected sugars in aqueous media via a one-pot chemoenzymatic process of three reactions; the direct synthesis of 4,6-dimethoxy-1,3,5-triazin-2-yl glycosides from unprotected sugars, a glycosidase-catalysed glycosylation using the triazinyl glycoside to afford glycomonomers and a radical polymerisation. The resulting glycopolymers exhibited specific interactions with the corresponding lectin as glycoclusters.

Functional Glycopolypeptides: Synthesis and Biomedical Applications

Employing natural-based renewable sugar and saccharide resources to construct functional biopolymer mimics is a promising research frontier for green chemistry and sustainable biotechnology. As the mimics/analogues of natural glycoproteins, synthetic glycopolypeptides attracted great attention in the field of biomaterials and nanobiotechnology. This review describes the synthetic strategies and methods of glycopolypeptides and their analogues, the functional self-assemblies of the synthesized glycopolypeptides, and their biological applications such as biomolecular recognition, drug/gene delivery, and cell adhesion and targeting, as well as cell culture and tissue engineering. Future outlook of the synthetic glycopolypeptides was also discussed.

Bottlebrush Glycopolymers from 2-Oxazolines and Acrylamides for Targeting Dendritic Cell-Specific Intercellular Adhesion Molecule-3-Grabbing Nonintegrin and Mannose-Binding Lectin

Lectins are omnipresent carbohydrate binding proteins that are involved in a multitude of biological processes. Unearthing their binding properties is a powerful tool toward the understanding and modification of their functions in biological applications. Herein, we present the synthesis of glycopolymers with a brush architecture via a "grafting from" methodology. The use of a versatile 2-oxazoline inimer was demonstrated to open avenues for a wide range of 2-oxazoline/acrylamide bottle brush polymers utilizing aqueous Cu-mediated reversible deactivation radical polymerization (Cu-RDRP). The polymers in the obtained library were assessed for their thermal properties in aqueous solution and their binding toward the C-type animal lectins dendritic cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN) and mannose-binding lectin (MBL) via surface plasmon resonance spectrometry. The encapsulation properties of a hydrophobic drug-mimicking compound demonstrated the potential use of glyco brush copolymers in biological applications.

Synthesis and Aggregation Behavior of Temperature- and pH-Responsive Glycopolymers as Sugar-Displaying Conjugates

Stimuli-responsive polymers have attracted significant interest in the fields of advanced materials and biomaterials. Herein, temperature- and pH-responsive glycopolymers, which are composed of N-isopropylacrylamide, methacrylic acid, and an acrylamide derivative bearing a lactose moiety, were synthesized via radical copolymerization. The series of resulting glycopolymers had different degrees of substitution of the lactose moieties, were responsive to temperatures between 26.6 °C and 47.6 °C, and formed aggregates above the lower critical solution temperature limit in mild acidic aqueous media (pH 4-6). The temperature-responsive behavior was dependent on the prevailing pH conditions, as no aggregation was observed in neutral and basic aqueous media (pH > 7). The aggregates had saccharide moieties on the surface in aqueous media. The number of saccharide moieties on the surface depended on the saccharide-containing unit ratio in the glycopolymer. The ratio was determined via enzymatic hydrolysis of the lactose moieties using β-galactosidase and the subsequent detection of the released galactose.

Probing the glycopolymer–ion interaction via specific ion effects

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

Controlled polymerization for the development of bioconjugate polymers and materials

Conjugates of various biopolymers with synthetic polymers were preparedvialiving radical polymerization. The conjugates have precise structures and potential for novel biofunctional materials.

Glyco-nanoparticles: New drug delivery systems in cancer therapy

Cancer is known as one of the most common diseases that are associated with high mobility and mortality in the world. Despite several efforts, current cancer treatment modalities often are highly toxic and lack efficacy and specificity. However, the application of nanotechnology has led to the development of effective nanosized drug delivery systems which are highly selective for tumors and allow a slow release of active anticancer agents. Different Nanoparticles (NPs) such as the silicon-based nano-materials, polymers, liposomes and metal NPs have been designed to deliver anti-cancer drugs to tumor sites. Among different drug delivery systems, carbohydrate-functionalized nanomaterials, specially based on their multi-valent binding capacities and desirable bio-compatibility, have attracted considerable attention as an excellent candidate for controlled release of therapeutic agents. In addition, these carbohydrate functionalized nano-carriers are more compatible with construction of the intracellular delivery platforms like the carbohydrate-modified metal NPs, quantum dots, and magnetic nano-materials. In this review, we discuss recent research in the field of multifunctional glycol-nanoparticles (GNPs) intended for cancer drug delivery applications.

Polyester-based ink platform with tunable bioactivity for 3D printing of tissue engineering scaffolds

In this work, we synthesized a novel polymeric biomaterial platform with tunable functionalizability for extrusion-based 3D printing. Biodegradable polymers were synthesized using 4-hydroxyphenethyl 2-(4-hydroxyphenyl)acetate (HTy), which is derived from Tyrosol and 2-(4-hydroxyphenyl)acetic acid. p-Phenylenediacetic acid (PDA) was introduced to enhance crystallinity. To enable functionalizability without deteriorating printability, glutamic acid derivatives were introduced into the polymer design, forming copolymers including poly(HTy-co-45%PDA-co-5%Gluhexenamide ester) (HP5GH), poly(HTy-co-45%PDA-co-5%Glupentynamide ester) (HP5GP), and poly(HTy-co-45%PDA-co-5%BocGlu ester) (HP5BG). The resulting polymers have: two melting temperatures (125-131 °C and 141-147 °C), Young's moduli of 1.9-2.4 GPa, and print temperatures of 170-190 °C. The molecular weight (Mw) loss due to hydrolytic degradation was gradual with ∼30% Mw retained after 25 weeks for HP5BG, whereas it was much faster for HP5GP and HP5GH with only 18% Mw retained after 8 weeks. HP5GH and HP5GP were successfully functionalized in solution (bulk) or on the surface using click-based chemistry. Finally, the utilization of this novel platform was demonstrated by studying osteogenic differentiation of human mesenchymal stem cells (hMSCs) using 3D printed scaffolds from HP5GP. Scaffolds were functionalized with azide-Heparin (az-Heparin) to bind and deliver bone morphogenetic protein 2 (BMP-2). This sample group significantly enhanced osteogenic differentiation of hMSCs as compared to unfunctionalized scaffolds incubated directly with az-Heparin or BMP-2 prior to cell culture. This novel polymer platform with tunable functionalizability could be utilized for additive manufacturing of biodegradable devices and scaffolds with tailored mechanical and bioactive properties for a wide range of medical applications including bone fixation devices and scaffolds for bone regeneration.

Polydimethylsiloxane-Based Giant Glycosylated Polymersomes with Tunable Bacterial Affinity

A synthetic cell mimic in the form of giant glycosylated polymersomes (GGPs) comprised of a novel amphiphilic diblock copolymer is reported. A synthetic approach involving a poly(dimethylsiloxane) (PDMS) macro-chain transfer agent (macroCTA) and postpolymerization modification was used to marry the hydrophobic and highly flexible properties of PDMS with the biological activity of glycopolymers. 2-Bromoethyl acrylate (BEA) was first polymerized using a PDMS macroCTA ( M_n,th ≈ 4900 g·mol^-1, Đ = 1.1) to prepare well-defined PDMS- b-pBEA diblock copolymers ( Đ = 1.1) that were then substituted with 1-thio-β-d-glucose or 1-thio-β-d-galactose under facile conditions to yield PDMS- b-glycopolymers. Compositions possessing ≈25% of the glycopolymer block (by mass) were able to adopt a vesicular morphology in aqueous solution (≈210 nm in diameter), as indicated by TEM and light scattering techniques. The resulting carbohydrate-decorated polymersomes exhibited selective binding with the lectin concanavalin A (Con A), as demonstrated by turbidimetric experiments. Self-assembly of the same diblock copolymer compositions using an electroformation method yielded GGPs (ranging from 2-20 μm in diameter). Interaction of these cell-sized polymersomes with fimH positive E. coli was then studied via confocal microscopy. The glucose-decorated GGPs were found to cluster upon addition of the bacteria, while galactose-decorated GGPs could successfully interact with (and possibly immobilize) the bacteria without the onset of clustering. This demonstrates an opportunity to modulate the response of these synthetic cell mimics (protocells) toward biological entities through exploitation of selective ligand-receptor interactions, which may be readily tuned through a considered choice of carbohydrate functionality.

Synthesis of Carbohydrate-Grafted Glycopolymers Using a Catalyst-Free, Perfluoroarylazide-Mediated Fast Staudinger Reaction

Glycopolymers have gained increasing importance in investigating glycan-lectin interactions, as drug delivery vehicles and in modulating interactions with proteins. The synthesis of these glycopolymers is still a challenging and rigorous exercise. In this regard, the highly efficient click reaction, copper (I)-catalyzed alkyne-azide cycloaddition, has been widely applied not only for its efficiency but also for its tolerance of the appended carbohydrate groups. However, a significant drawback of this method is the use of the heavy metal catalyst which is difficult to remove completely, and ultimately toxic to biological systems. In this work, we present the synthesis of carbohydrate-grafted glycopolymers utilizing a mild and catalyst-free perfluorophenyl azide (PFPA)-mediated Staudinger reaction. Using this strategy, mannose (Man) and maltoheptaose (MH) were grafted onto the biodegradable poly(lactic acid) (PLA) by stirring a PFAA-functionalized PLA with a phosphine-derivatized Man or MH in DMSO at room temperature within an hour. The glycopolymers were characterized by ¹H-NMR, 19F-NMR, 31P-NMR and FTIR.

Controlled synthesis of glycopolymers with pendant complex-type sialylglycopeptides and their binding affinity with a lectin and an influenza virus

Glycopolymers with pendant complex-type sialylglycopeptides (SGPs) were synthesized by a post-polymerization approach. The resulting glycopolymers strongly interacted with a lectin and an influenza virus.

Porous MnFe2O4@SiO2 magnetic glycopolymer: A multivalent nanostructure for efficient removal of bacteria from aqueous solution

The focuses of this research is to prepare an efficient magnetic glycopolymer for bacteria removal from aqueous solution. To perform this idea; porous MnFe₂O₄@SiO₂ was functionalized with glucose and or maltose as an anchors to adhere onto bacteria cell surface. Aminopropyltriethoxysilane was employed to link the saccharides on magnetic nanoparticle surface. The hybrid materials were characterized with XRD, VSM, FT-IR, FESEM, TEM, zeta potential measurement and elemental mapping. Microscopic image showed that MnFe₂O₄ is in cluster form composed from tiny nanoparticles. After saccharide functionalization hybrid composite generate hyper-crosslinked porous structure as a result of polysilicate formation due to hydrolysis of silica source. Escherichia coli and bacillus subtilis were selected as sample pathogens to evaluate the bacteria capturing ability of the magnetic glycopolymer. At the optimum conditions (pH = 6, time of 20 min, dosage of 15 mg) removal efficiency was more than 99% using both saccharide.

An Oxygen-Tolerant PET-RAFT Polymerization for Screening Structure-Activity Relationships

The complexity of polymer-protein interactions makes rational design of the best polymer architecture for any given biointerface extremely challenging, and the high throughput synthesis and screening of polymers has emerged as an attractive alternative. A porphyrin-catalysed photoinduced electron/energy transfer-reversible addition-fragmentation chain-transfer (PET-RAFT) polymerisation was adapted to enable high throughput synthesis of complex polymer architectures in dimethyl sulfoxide (DMSO) on low-volume well plates in the presence of air. The polymerisation system shows remarkable oxygen tolerance, and excellent control of functional 3- and 4-arm star polymers. We then apply this method to investigate the effect of polymer structure on protein binding, in this case to the lectin concanavalin A (ConA). Such an approach could be applied to screen the structure-activity relationships for any number of polymer-protein interactions.

The effect of linker length on ConA and DC-SIGN binding of S-glucosyl functionalized poly(2-oxazoline)s

A series of poly(2-oxazoline) based glycopolymers with different linkers were prepared via thiol–ene click reaction and cationic ring opening reaction. The binding of these polymers to lectins were studied.

Tailored Modification of Thioacrylates in a Versatile, Sequence-Defined Procedure

A strategy for the synthesis of sequence-defined oligomers using a selective side-group insertion approach making use of thiophenol-catalyzed amidation reactions is herein reported. In this context, a new thiolactone-based, multistep, iterative protocol is designed, utilizing thioacrylates in combination with solid-phase synthesis for step-by-step growth, resulting in sequence-defined oligomers. Sequence definition and structure variation are introduced by substituting the thioacrylate side groups with a wide variety of amines. The step-by-step growth of the oligomers is followed by liquid chromatography-mass spectrometry and high-resolution mass spectroscopy to determine both conversion and purity.

Specific and Differential Binding of N-Acetylgalactosamine Glycopolymers to the Human Macrophage Galactose Lectin and Asialoglycoprotein Receptor

A range of glycopolymers composed of N-acetylgalactosamine were prepared via sequential Cu(I)-mediated polymerization and alkyne-azide click (CuAAC). The resulting polymers were shown, via multichannel surface plasmon resonance, to interact specifically with human macrophage galactose lectin (MGL; CD301) with high affinity (K_D = 1.11 μM), but they did not bind to the mannose/fucose-selective human lectin dendritic-cell-specific intercellular adhesion molecule-3-grabbing nonintegrin (DC-SIGN; CD209). The effect of sugar ligand valency on the binding (so-called "glycoside cluster effect") of poly(N-acetylgalactosamine) to MGL was investigated by varying first the polymer chain length (DP: 100, 64, 40, 23, 12) and then the architecture (4- and 8-arm star glycopolymers). The chain length did not have a significant effect on the binding to MGL (K_D = 0.17-0.52 μM); however, when compared to a hepatic C-type lectin of a similar monosaccharide specificity, the asialoglycoprotein receptor (ASGPR), the binding affinity was more noticeably affected (K_D = 0.37- 6.65 μM). These data suggest that known differences in the specific configuration/orientation of the carbohydrate recognition domains of MGL and ASGPR are responsible for the differences in binding observed between the different polymers of varied chain length and architecture. In the future, this model has the potential to be employed for the development of tissue-selective delivery systems.

d-Fructose-Decorated Poly(ethylene imine) for Human Breast Cancer Cell Targeting

The high affinity of GLUT5 transporter for d-fructose in breast cancer cells has been discussed intensely. In this contribution, high molar mass linear poly(ethylene imine) (LPEI) is functionalized with d-fructose moieties to combine the selectivity for the GLUT5 transporter with the delivery potential of PEI for genetic material. The four-step synthesis of a thiol-group bearing d-fructose enables the decoration of a cationic polymer backbone with d-fructose via thiol-ene photoaddition. The functionalization of LPEI is confirmed by 2D NMR techniques, elemental analysis, and size exclusion chromatography. Importantly, a d-fructose decoration of 16% renders the polymers water-soluble and eliminates the cytotoxicity of PEI in noncancer L929 cells, accompanied by a reduced unspecific cellular uptake of the genetic material. In contrast, the cytotoxicity as well as the cell specific uptake is increased for triple negative MDA-MB-231 breast cancer cells. Therefore, the introduction of d-fructose shows superior potential for cell targeting, which can be assumed to be GLUT5 dependent.

Macromolecular Coupling in Seconds of Triazolinedione End-Functionalized Polymers Prepared by RAFT Polymerization

The ultrafast and additive-free triazolinedione-click reaction with electron rich (di)enes is a powerful method for the ultrafast ligation of polymer segments. A versatile method is described for the introduction of clickable TAD end groups in various polymer segments, using reversible addition-fragmentation chain transfer polymerization. These triazolinedione-functionalized prepolymers were subsequently used for macromolecular functionalization with a low molecular weight diene and block copolymer synthesis of different types within seconds, at ambient conditions, through the coupling with diene-functionalized polymers such as poly(ethylene glycol) and poly(isobornyl acrylate).