Synthesis of calixarene derivatives active towards proteic targets involved in tumor pathologies

2014 - 2015Over the last 30 years a growing interest has been direct toward the biomolecular recognition of calixarene derivatives and more in particular to the interaction with druggable target(s).1,2 The aim of this PhD thesis was the synthesis and the study of calixarenes that were able to interact with biomolecules involved in tumor pathologies. One of the main topic of this work was the synthesis of calix[4]arene conjugates bearing pyrenylisoxazolidine moieties at the exo rim which could act as potential DNA intercalators. The in vitro cytotoxic activity against different human tumor cell lines was also tested. Moreover, the biomolecular recognition abilities of designed calixarenes was studied through a chemical proteomics approach. As calix[n]arene scaffolds are particularly suitable for the synthesis of multivalent ligands,3 the attention was also focused on the synthesis of multivalent iminosugar-calix[8]arene conjugates for the inhibition of glycosidases. The synthesis, characterization and all the biomolecular recognition studies were herein described. [edited by author]XIV n.s

Precise generation of selective surface-confined glycoprotein recognition sites

Since glycoproteins have become increasingly recognized as key players in a wide variety of disease processes, there is an increasing need for advanced affinity materials for highly selective glycoprotein binding. Herein, for the first time, a surface-initiated controlled radical polymerization is integrated with supramolecular templating and molecular imprinting to yield highly reproducible synthetic recognition sites on surfaces with dissociation constants (KDs) in the low micromolar range for target glycoproteins and minimal binding to non-target glycoproteins. Importantly, it is shown that the synthetic strategy has remarkable ability to distinguish the glycosylated and non-glycosylated forms of the same glycoprotein, with >5-fold difference in binding affinity. The precise control over the polymer film thickness and positioning of multiple carbohydrate receptors plays a crucial role in achieving enhanced affinity and selectivity. The generated functional materials of unprecedented glycoprotein recognition performance open up a wealth of opportunities in the biotechnological and biomedical fields

Reversible, High-Affinity Surface Capturing of Proteins Directed by Supramolecular Assembly

The ability to design surfaces with reversible, high-affinity protein binding sites represents a significant step forward in the advancement of analytical methods for diverse biochemical and biomedical applications. Herein, we report a dynamic supramolecular strategy to directly assemble proteins on surfaces based on multivalent host–guest interactions. The host–guest interactions are achieved by one-step nanofabrication of a well-oriented β-cyclodextrin host-derived self-assembled monolayer on gold (β-CD-SAM) that forms specific inclusion complexes with hydrophobic amino acids located on the surface of the protein. Cytochrome c, insulin, α-chymotrypsin, and RNase A are used as model guest proteins. Surface plasmon resonance and static time-of-flight secondary ion mass spectrometry studies demonstrate that all four proteins interact with the β-CD-SAM in a specific manner via the hydrophobic amino acids on the surface of the protein. The β-CD-SAMs bind the proteins with high nanomolar to single-digit micromolar dissociation constants (KD). Importantly, while the proteins can be captured with high affinity, their release from the surface can be achieved under very mild conditions. Our results expose the great advantages of using a supramolecular approach for controlling protein immobilization, in which the strategy described herein provides unprecedented opportunities to create advanced bioanalytic and biosensor technologies

On-demand electrical switching of antibody-antigen binding on surfaces

The development of stimuli-responsive interfaces between synthetic materials and biological systems is providing the unprecedented ability to modulate biomolecular interactions for a diverse range of biotechnological and biomedical applications. Antibody–antigen binding interactions are at the heart of many biosensing platforms, but no attempts have been made yet to control antibody–antigen binding in an on-demand fashion. Herein, a molecular surface was designed and developed that utilizes an electric potential to drive a conformational change in surface bound peptide moiety, to give on-demand control over antigen–antibody interactions on sensor chips. The molecularly engineered surfaces allow for propagation of conformational changes from the molecular switching unit to a distal progesterone antigen, resulting in promotion (ON state) or inhibition (OFF state) of progesterone antibody binding. The approach presented here can be generally applicable to other antigen–antibody systems and meets the technological needs for in situ long-term assessment of biological processes and disease monitoring on-demand

A Click Ligation Based on SuFEx for the Metal-Free Synthesis of Sugar and Iminosugar Clusters

International audienceAlthough the preparation of anomeric glycosyl-sulfonyl fluoride was unsuccessful, a tetra-O-acetylatedC-gluc-osylpropanesulfonyl fluoride was synthesized starting from thecorresponding thioacetate via sulfonate formation as the keyintermediate. This sulfonyl fluoride was a bench-stable productthat reacted promptly with primary and secondary alkylaminesat 80 °C to give the corresponding sulfonamides in good yield.On the other hand, the same fluoridewas inert toward aryl-amines whereas its precursor, the sulfonyl chloride, showedgood reactivity. Another limitation of the acetylated sugar sulf-onyl fluoride was its lack of reactivity with a multivalentaminated calixarene, this being due to acetyl transfer from thecarbohydrate moiety to the aminogroups of the scaffold. Fortu-nately, the tetra-O-benzylatedC-glucosylpropanesulfonyl fluor-ide, prepared by the same reaction sequence employed for the synthesis of the acetylated analogue, reacted with the tetra-aminopropyl-calix[4]arene to afford the corresponding sulfon-amide-linked sugar cluster in high isolated yield. A similar ap-proach to the synthesis of calixarene-based iminosugar clusterswas unsuccessful because 1-deoxynojirimycin sulfonyl fluoridederivatives could not be generated. However, a tetra-propyl-sulfonyl fluoride calixarene, obtained from the free-OH calix-[4]arene through a three-step reaction sequence, underwentclean coupling with bothC-glucosylpropylamine andN-amino-pentyl-1-deoxy-deoxynojirimycin derivatives to give the corre-sponding tetravalent sugarand iminosugar clusters. This metal-free click reaction may constitute a valuable tool in the arsenalof ligation tools for the synthesis of multivalent carbohydratearchitecture