Interactions between glycans and proteins have tremendous impact in biomolecular interactions. They are important for cell–cell interactions, proliferation and much more. Here, we emphasize the glycan-mediated interactions between pathogens and host cells. Pseudomonas aeruginosa, responsible for a huge number of nosocomial infections, is especially the focus when it comes to glycan-derivatives as pathoblockers. We present a microwave assisted protecting group free synthesis of glycomonomers based on lactose, melibiose and fucose. The monomers were polymerized in a precipitation polymerization in the presence of NiPAm to form crosslinked glyco-nanogels. The influence of reaction parameters like crosslinker type or stabilizer amount was investigated. The gels were characterized in lectin binding studies using model lectins and showed size and composition-dependent inhibition of lectin binding. Due to multivalent presentation of glycans in the gel, the inhibition was clearly stronger than with unmodified saccharides, which was compared after determination of the glycan loading. First studies with Pseudomonas aeruginosa revealed a surprising influence on the secretion of virulence factors. Functional glycogels may be in the future potent alternatives or adjuvants for antibiotic treatment of infections based on glycan interactions between host and pathogen.
Despite the growing need for readily
available and inexpensive
catalysts for the half-reactions involved in water splitting, water
oxidation and reduction electrocatalysts are still traditionally based
on noble metals. One long-standing challenge has been the development
of an oxygen evolution reaction catalyzed by easily available, structurally
simple, and purely organic compounds. Herein, we first generalize
the performance of the known N-ethyl-flavinium ion
to a number of derivatives. Furthermore, we demonstrate an unprecedented
application of different pyridinium and related salts as very simple,
inexpensive water oxidation organocatalysts consisting of earth-abundant
elements (C, H, O, and N) exclusively. The results establish the prospects
of heterocyclic aromatics for further design of new organic electrocatalysts
for this challenging oxidation reaction.
Glycans carry a vast range of functions in nature. Utilizing their properties and functions in form of polymers, coatings or glycan derivatives for various applications makes the synthesis of modified glycans crucial. Since amines are easy to modify for subsequent reactions, we investigated regioselective amination conditions of different saccharides. Amination reactions were performed according to Kochetkov and Likhoshertov and accelerated by microwave irradiation. We optimized the synthesis of glycosylamines for N-acetyl-d-galactosamine, d-lactose, d-glucuronic acid and l-(−)-fucose using the design of experiments (DoE) approach. DoE enables efficient optimization with limited number of experimental data. A DoE software generated a set of experiments where reaction temperature, concentration of carbohydrate, nature of aminating agent and solvent were investigated. We found that the synthesis of glycosylamines significantly depends on the nature of the carbohydrate and on the reaction temperature. There is strong indication that high temperatures are favored for the amination reaction.
The base pairing property and the “melting” behavior of oligonucleotides can take advantage to develop new smart thermoresponsive and programmable materials.
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