A thiol-ene mediated approach for peptide bioconjugation using 'green' solvents under continuous flow

Flow chemistry has emerged as an integral process within the chemical sector permitting energy efficient synthetic scale-up while improving safety and minimising solvent usage. Herein, we report the first applications of the photoactivated, radical-mediated thiol-ene reaction for peptide bioconjugation under continuous flow. Bioconjugation reactions employing deep eutectic solvents, bio-based solvents and fully aqueous systems are reported here for a range of biologically relevant peptide substrates. The use of a water soluble photoinitiator, Irgacure 2959, permitted synthesis of glycosylated peptides in fully aqueous conditions, obviating the need for addition of organic solvents and enhancing the green credentials of these rapid, photoactivated, bioconjugation reactions.

Synthesis of Mannosylated Glycodendrimers and Evaluation against BC2L-A Lectin from Burkholderia Cenocepacia

Chronic colonization of lungs by opportunist bacteria is the major cause of mortality for cystic fibrosis patients. Among these pathogens, Burkholderia cenocepacia is responsible for cepacia syndrome, a deadly exacerbation of infection that is the main cause of poor outcomes of lung transplantation. This bacterium contains three soluble carbohydrate-binding proteins, including the B. cenocepacia lectin A (BC2L-A), which is proposed to bind to oligomannose-type N-glycan structures to adhere to host tissues. In this work, several mannosylated glycoclusters and glycodendrimers with valencies ranging from four to 24 were prepared and their interactions with BC2L-A were thermodynamically characterized by isothermal titration calorimetry. The results show that a 24-valent structure binds to BC2L-A at nanomolar concentration, which makes this compound the highest affinity monodisperse ligand for this lectin.

Tri- and tetravalent mannoclusters cross-link and aggregate BC2L-A lectin from Burkholderia cenocepacia

The opportunistic Gram-negative bacterium Burkholderia cenocepacia causes lethal infections in cystic fibrosis patients. Multivalent mannoside derivatives were prepared as potential inhibitors of lectin BC2L-A, one of the virulence factors deployed by B. cenocepacia in the infection process. An (α1→2)-thio-linked mannobioside mimic bearing an azide functionalized aglycon was conjugated to different multivalent scaffolds such as propargylated calix[4]arenes, methyl gallate and pentaerythritol by azide-alkyne 1,3-dipolar cycloaddition. The interaction between the glycoclusters and the mannose binding BC2L-A lectin from B. cenocepacia was examined by isothermal microcalorimetry, surface plasmon resonance, inhibition of yeast agglutination and analytical ultracentrifugation.

Preparation of glyco-silica materials via thiol-ene click chemistry for adsorption and separation

A saccharide bonding method based on thiol-ene chemistry was developed and the resulting glyco-silica materials demonstrated great potential in separation science.