Convergent Synthesis of Glycodendropeptides by Click Chemistry Approaches

Thiol-Ene Click-Inspired Late-Stage Modification of Long-Chain Polyurethane Dendrimers

The construction of well-defined polyurethane dendrimers is challenging due to the high reactivity of externally added or in situ formed isocyanates leading to the formation of side products. With a primary focus of dendrimer research being the interaction of the periphery and the core, we report the synthesis of a common polyurethane dendron, which allows for the late-stage variation of both the periphery and the core. The periphery can be varied simply by installing a clickable unit in the dendron and then attaching to the core and vice-versa. Thus, a common dendron allows for varying periphery and core in the final two steps. To accomplish this, a protecting group-free, one-pot multicomponent Curtius reaction was utilized to afford a robust and versatile AB2 type polyurethane dendron employing commercially available simple molecules: 5-hydroxyisophthalic acid, 11-bromoundecanol, and 4-penten-1-ol. Subsequent late-stage modifications of either dendrons or dendrimers via a thiol-ene click reaction gave surface-functionalized alternating aromatic-aliphatic polyurethane homodendrimers to generation-three (G3). The dendrons and the dendrimers were characterized by NMR, mass spectrometry, and FT-IR analysis. A bifunctional AB2 type dendritic monomer demonstrated this approach’s versatility that can either undergo a thiol-ene click or attachment to the core. This approach enables the incorporation of functionalities at the periphery and the core that may not withstand the dendrimer growth for the synthesis of polyurethane dendrimers and other dendritic macromolecules.

Peptide-Based Multiepitopic Vaccine Platforms via Click Reactions

Multimeric antigen display and high overall valency are increasingly regarded as strategic goals for potent and broadly efficacious synthetic vaccines with potential market prospects. Herein, a modular and versatile approach to multifunctional peptide-based vaccine platforms at multimilligram scale in reasonable yields is reported. Preparation of chemoselectively modified peptide building blocks of medium-to-large size, conjugation of these subunits, and final assembly were achieved by a combination of Michael-type thiol-ene addition and copper(I)-mediated alkyne-azide cycloaddition. The size and structural complexity of the building blocks required exploration of a further level of orthogonality, namely furan/maleimide Diels-Alder chemistry. After process optimization, a finely tuned, stepwise click approach has emerged as a workable, on-demand strategy to create macromolecular therapeutic vaccine assemblies.

Glycosylated nanostructures in sublingual immunotherapy induce long-lasting tolerance in LTP allergy mouse model

An effective specific immunotherapy should contain elements to generate specific recognition (T-cell peptides) and to modulate the immunological response towards a Th1/Treg pattern by enhancing dendritic cells (DCs). We propose a novel sublingual immunotherapy for peach allergy, using systems, that combine Prup3-T-cell peptides with mannose dendrons (D₁ManPrup3 and D₄ManPrup3). Peach anaphylactic mice were treated 1, 2 and 5 nM concentrations. Tolerance was assessed one/five weeks after finishing treatment by determining in vivo/in vitro parameters after challenge with Prup3. Only mice receiving D₁ManPrup3 at 2 nM were protected from anaphylaxis (no temperature changes, decrease in Prup3-sIgE and -sIgG1 antibody levels, and secreting cells) compared to PBS-treated mice. Moreover, an increase of Treg-cells and regulatory cytokines (IL-10⁺/IFN-γ⁺) in CD4⁺-T-cells and DCs were found. These changes were maintained at least five weeks after stopping treatment. D₁ManPrup3 is an effective new approach of immunotherapy inducing protection from anaphylaxis which persists after finishing treatment.

Analysis of carbohydrates and glycoconjugates by matrix-assisted laser desorption/ionization mass spectrometry: An update for 2011-2012

This review is the seventh update of the original article published in 1999 on the application of MALDI mass spectrometry to the analysis of carbohydrates and glycoconjugates and brings coverage of the literature to the end of 2012. General aspects such as theory of the MALDI process, matrices, derivatization, MALDI imaging, and fragmentation are covered in the first part of the review and applications to various structural types constitute the remainder. The main groups of compound are oligo- and poly-saccharides, glycoproteins, glycolipids, glycosides, and biopharmaceuticals. Much of this material is presented in tabular form. Also discussed are medical and industrial applications of the technique, studies of enzyme reactions, and applications to chemical synthesis. © 2015 Wiley Periodicals, Inc. Mass Spec Rev 36:255-422, 2017.

The modular synthesis of multivalent functionalised glycodendrons for the detection of lectins including DC-SIGN

A modular approach towards glycoconjugate probes allows for the versatile synthesis of dendrons with reporter groups and glycans of choice.

Peptide-based synthetic vaccines

Classically all vaccines were produced using live or attenuated microorganisms or parts of them. However, the use of whole organisms, their components or the biological process for vaccine production has several weaknesses. The presence of immunologically redundant biological components or biological impurities in such vaccines might cause major problems. All the disadvantageous of traditional vaccines might be overcome via the development of fully synthetic peptide-based vaccines. However, once minimal antigenic epitopes only are applied for immunisation, the immune responses are poor. The use of an adjuvant can overcome this obstacle; however, it may raise new glitches. Here we briefly summarise the current stand on peptide-based vaccines, discuss epitope and adjuvant design, and multi-epitope and nanoparticle-based vaccine approaches. This mini review discusses also the disadvantages and benefits associated with peptide-based vaccines. It proposes possible methods to overcome the weaknesses of the synthetic vaccine strategy and suggests future directions for its development.

Dendron-Mediated Engineering of Interparticle Separation and Self-Assembly in Dendronized Gold Nanoparticles Superlattices

Self-assembly of nanoparticles into designed structures with controlled interparticle separations is of crucial importance for the engineering of new materials with tunable functions and for the subsequent bottom-up fabrication of functional devices. In this study, a series of lipophilic, highly flexible, disulfide dendritic wedges (generations 0-4), based on 2,2-bis(hydroxymethyl)propionic acid, was designed to bind Au nanoparticles with a thiolate bond. By controlling the solvent evaporation rate, the corresponding dendron-capped Au hybrids were found to self-organize into hexagonal close-packed (hcp) superlattices. The interparticular spacing was progressively varied from 2.2 to 6.3 nm with increasing dendritic generation, covering a range that is intermediate between commercial ligands and DNA-based ligand shells. Dual mixtures made from some of these dendronized hybrids (i.e., same inner core size but different dendritic covering) yielded binary superlattice structures of unprecedented single inorganic components, which are isostructural with NaZn13 and CaCu5 crystals.

Recent advances in click chemistry applied to dendrimer synthesis

Dendrimers are monodisperse polymers grown in a fractal manner from a central point. They are poised to become the cornerstone of nanoscale devices in several fields, ranging from biomedicine to light-harvesting. Technical difficulties in obtaining these molecules has slowed their transfer from academia to industry. In 2001, the arrival of the "click chemistry" concept gave the field a major boost. The flagship reaction, a modified Hüisgen cycloaddition, allowed researchers greater freedom in designing and building dendrimers. In the last five years, advances in click chemistry saw a wider use of other click reactions and a notable increase in the complexity of the reported structures. This review covers key developments in the click chemistry field applied to dendrimer synthesis from 2010 to 2015. Even though this is an expert review, basic notions and references have been included to help newcomers to the field.

Glycodendropeptides stimulate dendritic cell maturation and T cell proliferation: a potential influenza A virus immunotherapy

A GDP displaying the NP_366–374 influenza A virus epitope induces an immunostimulatory effect, emerging as a potential flu vaccine.

(99m)Tc-Galacto-RGD2: a novel 99mTc-labeled cyclic RGD peptide dimer useful for tumor imaging

This study sought to evaluate [(99m)Tc(HYNIC-Galacto-RGD2)(tricine)(TPPTS)] ((99m)Tc-Galacto-RGD2: HYNIC = 6-hydrazinonicotinyl; Galacto-RGD2 = Glu[cyclo[Arg-Gly-Asp-D-Phe-Lys(SAA-PEG2-(1,2,3-triazole)-1-yl-4-methylamide)]]2 (SAA = 7-amino-L-glycero-L-galacto-2,6-anhydro-7-deoxyheptanamide, and PEG2 = 3,6-dioxaoctanoic acid); and TPPTS = trisodium triphenylphosphine-3,3',3″-trisulfonate) as a new radiotracer for tumor imaging. Galacto-RGD2 was prepared via the copper(I)-catalyzed 1,3-dipolar azide-alkyne Huisgen cycloaddition. HYNIC-Galacto-RGD2 was prepared by reacting Galacto-RGD2 with sodium succinimidyl 6-(2-(2-sulfonatobenzaldehyde)hydrazono)nicotinate (HYNIC-OSu) in the presence of diisopropylethylamine, and was evaluated for its integrin αvβ3 binding affinity against (125)I-echistatin bound to U87MG glioma cells. The IC50 value for HYNIC-Galacto-RGD2 was determined to be 20 ± 2 nM. (99m)Tc-Galacto-RGD2 was prepared in high specific activity (∼ 185 GBq/μmol) and high radiochemical purity (>95%), and was evaluated in athymic nude mice bearing U87MG glioma xenografts for its tumor-targeting capability and biodistribution. The tumor uptake of (99m)Tc-Galacto-RGD2 was 10.30 ± 1.67, 8.37 ± 2.13, 6.86 ± 1.33, and 5.61 ± 1.52%ID/g at 5, 30, 60, and 120 min p.i., respectively, which was in agreement with high integrin αvβ3 expression on glioma cells and neovasculature. Its lower uptake in intestines, lungs, and spleen suggests that (99m)Tc-Galacto-RGD2 has advantages over (99m)Tc-3P-RGD2 ([(99m)Tc(HYNIC-3P-RGD2)(tricine)(TPPTS)]: 3P-RGD2 = PEG4-E[PEG4-c(RGDfK)]2; PEG4 = 15-amino-4,7,10,13-tetraoxapentadecanoic acid) for imaging tumors in the chest and abdominal regions. U87MG tumors were readily detected by SPECT and the tumor uptake of (99m)Tc-Galacto-RGD2 was integrin αvβ3-specific. (99m)Tc-Galacto-RGD2 also had very high metabolic stability. On the basis of results from this study, it was concluded that (99m)Tc-Galacto-RGD2 is an excellent radiotracer for imaging integrin αvβ3-positive tumors and related metastases.