Photo- and Electrochemical Dual-Responsive Iridium Probe for Saccharide Detection.

Andrew J Carrod,Louise Male,Zubair Ahmed,Mohamed Elsherif,Francesco Graglia,Haider Butt,Cécile Le Duff,Guang‐Xi Xu,Kenneth Kam‐Wing Lo,Peter Simpson,Paolo Bertoncello,Zoe Pikramenou

doi:10.1002/chem.202103541

Abstract

Dual detection systems are of interest for rapid, accurate data collection in sensing systems and in vitro testing. We introduce an IrIII complex with a boronic acid receptor site attached to the 2‐phenylpyridine ligand as an ideal probe with photo‐ and electrochemical signals that is sensitive to monosaccharide binding in aqueous solution. The complex displays orange luminescence at 618 nm, which is reduced by 70 and 40 % upon binding of fructose and glucose, respectively. The electro‐chemiluminescent signal of the complex also shows a direct response to monosaccharide binding. The IrIII complex shows the same response upon incorporation into hydrogel matrices as in solution, thus demonstrating the potential of its integration into a device, as a nontoxic, simple‐to‐use tool to observe sugar binding over physiologically relevant pH ranges and saccharide concentrations. Moreover, the complex's luminescence is responsive to monosaccharide presence in cancer cells.

Highlights

Dual-modality sensing by optical and electrochemical techniques is a popular detection strategy for analytes, for the high sensitivity and as an approach to eliminate false positives due to the differing signal transduction pathways in each detection method.[1]
An aqueous solution of the complex displays an emission band centred at 618 nm
We examined the binding of glucose and fructose to Ir-4BOH by titrations in aqueous solutions

Summary

Introduction

Transition metal complexes offer dualmode electrochemical and photoluminescence signals.[6] The design of polypyridine luminescent transition metal complexes with boronic acid recognition groups has been limited to the boronic acid connected either via a long aliphatic linker to the oligopyridine unit, or via phenyl linker In these cases either weak or no luminescent signal response was observed upon saccharide binding; alternatively conditions of high pH beyond physiological range were necessary to illicit a response. The studies were based on a single detection method.[7] We chose an iridium(III) photoactive core based on the sensitivity of the luminescence properties to local environmental changes, and for electrochemical properties.[8] we report an iridium(III) complex, Ir-4-BOH, with two boronic acid recognition sites grafted on the phenylpyridine ligand to bring the recognition site spatially closer to the metal centre. The versatility in the design of iridium(III) complexes as sensors can overcome challenges from solubility, working pH range, detection in different areas of the spectrum whilst providing a framework to build a recognition site

Results and Discussion

Conclusion

Conflict of Interest