Selective sensing of saccharides using simple boronic acids and their aggregates

Xin Wu,Tony D James,Xuan-Xuan Chen,Yun-Bao Jiang,Zhao Li,John S Fossey

doi:10.1039/c3cs60148j

Abstract

The reversible boronic acid-diol interaction empowers boronic acid receptors' saccharide binding capacities, rendering them a class of lectin mimetic, termed "boronlectins". Boronic acids follow lectin functions not just in being able to bind saccharides, but in multivalent saccharide binding that enhances both affinity and selectivity. For almost a decade, efforts have been made to achieve and improve selectivity for given saccharide targets, most notably glucose, by using properly positioned boronic acids, offering multivalent interactions. Incorporation of several boronic acid groups into a covalent framework or non-covalent assembly of boronic acid are two general methods used to create such smart sensors, of which the latter resembles lectin oligomerisation that affords multivalent saccharide-binding architectures. In this review, we discuss supramolecular selective sensing of saccharides by using simple boronic acids in their aggregate forms, after a brief survey of the general aspects of boronic acid-based saccharide sensing.

Highlights

The effectiveness of boronic acids as receptors in chemosensors for a range of biologically important species is perhaps nowhere more evident than in the myriad of publications related to this area
While multivalency is probably absent in glucose sensing by 36, another aggregation-based glucose sensor 3877 we recently developed clearly manifests the multivalency effect, with higher apparent affinity to glucose than to fructose
Selectivity inversion from fructose to glucose has been achieved by boronic acids with surprisingly simple structures in their aggregated state that affords multivalent binding which is unlikely from simple boronic acids

Summary

Introduction

The effectiveness of boronic acids as receptors in chemosensors for a range of biologically important species is perhaps nowhere more evident than in the myriad of publications related to this area. Alternatives to these diboronic acids, are the boronic acidcontaining polymers (Fig. 1b), in which multiple boronic acid moieties are covalently attached to the polymer backbone and thereby allow more than one pendant boronic acid moieties to interact with a saccharide molecule Both approaches resemble the cluster glycoside effect by a single lectin polypeptide containing many binding sites.[11] It is of interest, from a biomimetic point of view, to question whether synthetic ‘‘boronlectins’’ can follow another approach; that taken by naturally occurring lectins, i.e. the non-covalent aggregation,[10] to achieve higher affinity and selectivity for a given saccharide species. Some modestly selective sensors are included in this review

Key issues for boronic acid-based saccharide sensor design

Self-assembly of simple boronic acids for selective glucose sensing

Findings

Conclusions and perspectives