Designed boronate ligands for glucose-selective holographic sensors.

In this study, 2-acrylamidophenylboronate (2-APB) was synthesised and its ability to bind with glucose was investigated both in solution and when integrated into a holographic sensor. Multiple forms of 2-APB, resulting from the neighbouring effect of the amido group with the boronic acid through an intramolecular B--O-coordinated interaction, were shown to exist in solution by using multinuclear NMR spectrometry. It was found that 2-APB predominantly adopts a zwitterionic tetrahedral form at physiological pH values. The complex formation of 2-APB with glucose and lactate was investigated in DMSO; 2-APB favours binding with glucose rather than lactate and generates a five-membered-ring complex. Furthermore, a 2-APB-based holographic sensor displayed a significant response to glucose with little interference from lactate, and with no dependence on pH in the physiological pH range. These features suggest that the new ligand 2-APB is a potential candidate for the development of glucose-selective sensors.