Reversible Lectin Binding to Glycan-Functionalized Graphene.

Tereza Koukalová,Ivan Jirka,Petr Kovaříček,Martin Kalbáč,Lukáš Navara,Marek Cebecauer,Valentino L P Guerra,Vladimír Křen,Vladimír Vrkoslav,Pavla Bojarová

doi:10.3390/ijms22136661

Abstract

The monolayer character of two-dimensional materials predestines them for application as active layers of sensors. However, their inherent high sensitivity is always accompanied by a low selectivity. Chemical functionalization of two-dimensional materials has emerged as a promising way to overcome the selectivity issues. Here, we demonstrate efficient graphene functionalization with carbohydrate ligands—chitooligomers, which bind proteins of the lectin family with high selectivity. Successful grafting of a chitooligomer library was thoroughly characterized, and glycan binding to wheat germ agglutinin was studied by a series of methods. The results demonstrate that the protein quaternary structure remains intact after binding to the functionalized graphene, and that the lectin can be liberated from the surface by the addition of a binding competitor. The chemoenzymatic assay with a horseradish peroxidase conjugate also confirmed the intact catalytic properties of the enzyme. The present approach thus paves the way towards graphene-based sensors for carbohydrate–lectin binding.

Highlights

Two-dimensional (2D) materials hold a great potential for application as the active layers of sensors due to their strict monolayer character
Lectins play diverse roles in biological systems; they participate in cellular signaling, are involved in biochemical pathways leading to various pathologies, and are essential in cell–cell recognition in infectious diseases such as AIDS [8,9], tuberculosis [10], and even the SARS-CoV-2 virus [11]
Chitooligomers of different lengths carrying an azidoethyl substituent at the anomeric carbon were attached to the graphene surface using the standard CuAAC click reaction protocol in water [31]

Summary

Introduction

Two-dimensional (2D) materials hold a great potential for application as the active layers of sensors due to their strict monolayer character. The epitomical example of a 2D family of materials, can achieve sensitivity down to single atoms under particular conditions [1]. The cornerstone of graphene-based sensor development is to achieve selective recognition of a given analyte [2,3]. Lectins have been shown to form complex quaternary structures, ranging from dimers to higher homo- or heterooligomers up to chimeric structures that can gradually interchange [12,13]. This challenge is further complicated by the agglutinating properties of lectins and the chemical resemblance of their carbohydrate ligands

Methods

Results

Conclusion