Fibre optics, electrodes, fluorescent dyes - all have been used to monitor dynamic changes in oxygen concentration in biological systems. This is incredibly important - oxygen is a critical molecule for all aerobic organisms (and can be harmful to anaerobes), and deviations from homeostatis can tell us about metabolism, viability, cellular stress, and also the presence of cancers and other diseases. Indeed, Gabe wrote a review on this right here!
In this study, Gabe was able to create organosilica core-shell nanoparticles, which are labelled with an oxygen-sensitive dye in the porous shell, and an insensitive dye in the core, to produce ratiometric sensors that have very little "thermal drift" in comparison to the free oxygen dye. We characterised the material and sensor properties, ad then investigated their use for 1D (microwell) and 2D (microscope slides) bacterial cultures, showing that spatiotemporal monitoring is possible by visualising and tracking the ratiometric signals from many individual particles. Our recently confirmed student, Salma Sultana Tunny leant her expertise to this project, designing the Matlab scripts and related experiments that allowed us to process the data from the 2D experiments.