Saccharide/glycoprotein recognition inside synthetic ion channels modified with boronic acid

Here, we demonstrate a novel sensing platform for the molecular recognition of monosaccharides (glucose and fructose) and glycoprotein (ovalbumin) using synthetic ion channels fabricated in polymeric membrane. To achieve this, receptor (3-aminophenylboronic acid) is covalently attached with carboxylic groups on the surface and inner walls of the channel. The detection principle rests on the reversible binding occurring between boronic acid and diols of saccharides or glycoprotein molecules, leading to a sensible change in the ionic flux across the nanochannel. In the presence of saccharides or glycoprotein at neutral pH, saccharide-boronic acid complex changes the channel surface from neutral to negative. The binding of ovalbumin onto the channel surface also leads to the reduction of the effective channel diameter, which in turn diminishes the channel conductance. Based on the experimental results, we believe that the presented sensing platform could also be applicable in the area of biomedical sciences for the recognition of cell-surface carbohydrate moieties. (C) 2011 Elsevier B.V. All rights reserved.