Comparison of photo- and Cu(i)-catalyzed “click” chemistries for the formation of carbohydrate SPR interfaces

Abstract

Understanding interactions of glycans with proteins in key biological events has seen the development of various analytical methods such as microarray techniques. Label-free approaches, such as surface plasmon resonance (SPR) techniques are particularly attractive and we explore here the potential of a novel interface composed of lamellar Ti/Au/silicon dioxide derivatized with sugars to probe lectin-sugar interactions by SPR. Two parallel surface functionalization strategies have been developed: one in which azide-functionalized surfaces are linked via a Cu(I) "click" method to alkynyl-derivatized glycan partners and another wherein perfluorophenyl azide-functionalized surfaces are reacted through a C-H insertion photocoupling reaction with underivatized glycans. The effectiveness of the two interfaces is assessed for their lectin-recognition abilities in an SPR format.

Surface Plasmon Resonance (SPR) for the Evaluation of Shear-Force-Dependent Bacterial Adhesion

“…The C1 S core level spectrum of the Au-HM interface shows next to the peak at 285.0 eV (aliphatic carbon atoms) contributions at 286.2 eV and 288.1 eV, characteristic of C–O bands of the integrated glycans and the formed amide bond, respectively ( Figure 1 b). The degree of sugar loading was determined using the classical phenol-sulfuric acid method as described in several papers by us [ 30 , 33 ]. A loading of (8.5 ± 0.6) × 10 14 molecules·cm −2 was thus determined, in accordance with other reports on mannose-modified SPR surfaces [ 33 , 34 ].…”

“…The degree of sugar loading was determined using the classical phenol-sulfuric acid method as described in several papers by us [ 30 , 33 ]. A loading of (8.5 ± 0.6) × 10 14 molecules·cm −2 was thus determined, in accordance with other reports on mannose-modified SPR surfaces [ 33 , 34 ].…”

Antibacterial Applications of Nanodiamonds

“…The resulting highly reactive nitrene intermediates are believed to interact with glycans through C-H and/or N-H insertion reactions, creating highly robust covalent linkages. We have recently compared the effectiveness for lectin-recognition ability of mannose-modified surfaces formed photochemically or via Cu(I)-catalyzed “click” chemistry using surface plasmon resonance (SPR) [ 60 ]. Although photochemical surface conjugation did not give surface attachment specifically through anomeric center, this was seen not to have a bearing on the SPR behavior of the fabricated sugar interfaces, maintaining their expected binding affinity and specificity towards their partner lectins.…”

Affinity of Glycan‐Modified Nanodiamonds towards Lectins and Uropathogenic Escherichia Coli

“…The highly reactive nitrene intermediate formed is believed to interact with glycans through C−H and N−H insertion reactions, creating highly robust covalent linkages. We recently compared the effectiveness of mannose‐modified surfaces either formed photochemically or via Cu I “click” reactions for lectin recognition using surface plasmon resonance . Although photochemical surface conjugation did not give anomeric center‐specific surface attachment, this was seen not to have a bearing on lectin recognition, with preserved binding affinity and specificity.…”