Development of Versatile Luminescent Sensors

Abstract

Lanthanide based probes and sensors have been widely utilised over the past few decades, particularly in the study of biological processes. The favourable photoluminescent properties of the lanthanide ions and the use of functionalised macrocyclic ligands that permit tuneable excitation means there is now a plethora of examples, across the scientific literature.
An azaxanthone-based chromophore has been incorporated into a cyclen ligand, and the ability of this complex to bind to proteins has been studied further, examining the possibility of personalised medicine. The complex competes with selectively chosen pharmaceutical compound in binding to the acute phase serum protein α1-AGP. This complex is one of the first examples which uses CPL to monitor a binding event.
The same chromophore, as well as the azathioxanthone analogue, have been utilised further in cyclen based complexes, with the aim of binding the controversial herbicide, glyphosate. Selectivity for glyphosate against other potential competitors has been studied, testing the ability of a series of structurally related complexes to operate in a variety of media.
The final chapter looks at a new family of compounds, which bear an extended chromophore and a tripicolylamine based arm. Again, these were tested for their ability to bind glyphosate selectively, in a range of media. Time-gated methodology was used to allow any unwanted organic auto-fluorescence to be removed, particularly in samples which may contain a lot of biological compounds. Following these studies, one complex was selected, testing whether the complex can be used to calculate the concentration of glyphosate in extract from spiked wheat and oat grains. This complex was able to be used over the range 0.5 to 60 micromolar of glyphosate with a limit of around 4 micromolar.