Carbohydrate−Protein Interactions by “Clicked” Carbohydrate Self-Assembled Monolayers

Abstract

A Huisgen 1,3-dipolar cycloaddition "click chemistry" was employed to immobilize azido sugars (mannose, lactose, alpha-Gal) to fabricate carbohydrate self-assembled monolayers (SAMs) on gold. This fabrication was based on preformed SAM templates incorporated with alkyne terminal groups, which could further anchor the azido sugars to form well-packed, stable, and rigid sugar SAMs. The clicked mannose, lactose, and alpha-Gal trisaccharide SAMs were used in the analysis of specific carbohydrate-protein interactions (i.e., mannose-Con A; ECL-lactose, alpha-Gal-anti-Gal). The apparent affinity constant of Con A binding to mannose was (8.7 +/- 2.8) x 10(5) and (3.9 +/- 0.2) x 10(6) M(-1) measured by QCM and SPR, respectively. The apparent affinity constants of lactose binding with ECL and alpha-Gal binding with polyclonal anti-Gal antibody were determined to be (4.6 +/- 2.4) x 10(6) and (6.7 +/- 3.3) x 10(6) M(-1), respectively by QCM. SPR, QCM, AFM, and electrochemistry studies confirmed that the carbohydrate SAM sensors maintained the specificity to their corresponding lectins and nonspecific adsorption on the clicked carbohydrate surface was negligible. This study showed that the clicked carbohydrate SAMs in concert with nonlabel QCM or SPR offered a potent platform for high-throughput characterization of carbohydrate-protein interactions. Such a combination should complement other methods such as ITC and ELISA in a favorable manner and provide insightful knowledge for the corresponding complex glycobiological processes.

Surface Reactions On Demand: Electrochemical Control of SAM‐Based Reactions

“…Instead of activating surface-bound reactants, such as HQ, Chidsey, Collman, and co-workers electrochemically activated a catalyst for copper(I)-catalyzed Huisgen 1,3-dipolar cycloaddition (Sharpless "click" chemistry) (Figure 2). [10] The click chemistry between azido and acetylenyl groups, leading to the formation of 1,2,3-triazoles, [11] has been applied to SAM-based reactions [12] because the reaction is fast and proceeds under mild aqueous conditions. To demonstrate individual addressability, they brought an electrode in contact with a solution containing copper(II) species, and biased the electrode at À300 mV versus a Ag/AgCl/ saturated NaCl reference electrode (roughly 300 mV negative of the copper-(II/I) standard potential).…”

Click Chemistry: Versatility and Control in the Hands of Materials Scientists

“…2). [31] It was found that these carbohydrate-based sensors maintained their specificity towards the corresponding proteins, which could lead to potential applications in high-throughput characterization of carbohydrate-protein interactions. In a very elegant approach reported by Mrksich's group, hydroquinone groups in SAMs were electrochemically oxidized into quinone groups that, in turn, underwent Diels-Alder reaction.…”

1,3‐Dipolare Cycloaddition von Aziden und Alkinen: eine universelle Ligationsmethode in den Polymer‐ und Materialwissenschaften

“…B. in der molekularen Elektronik, der Katalyse oder in Biosensoren geebnet. [83,84,[87][88][89][90] Außer zur Funktionalisierung von SAMs wurde die Huisgen-Cycloaddition von Alkinen und Aziden auch zum Aufbau Polymer-modifizierter Oberflächen genutzt. Caruso und Mitarbeiter entwickelten z.…”