The project will adapt a novel nanosensor technology, based on ultrafine nanoelectrodes, to enable accurate in-situ measurement of diagnostic, small-molecule analytes in biological and electro-catalytic systems. As it stands, the current nanoelectrode sensing technology suffers from poor signal/noise ratio that makes small changes in analyte concentration unnoticeable. The project will develop functional, graphene nanomaterials that will be incorporated into the nanoelectrode sensors to dramatically improve their sensitivity. Further, chemical modification of the graphene-modified nanosensors with bimetallic nanoparticles and/or functionalised polymers will be explored to boost selectivity. The novel functional nanosensors will initially be assessed for intracellular oxygen sensing with in bovine embryos, an important model system in reproductive medicine. There is strong evidence that monitoring the metabolic activity of the embryo, including oxygen consumption, will help clinical practitioners to select the "best" embryos in reproductive therapy. Due to their ultrafine dimensions, our nanoelectrode sensors will allow accurate oxygen measurements on a single cellular level while substantially minimising the risk of critical embryo perturbance. In parallel, the functional nanoelectrodes will also be explored for the sensing of reactive intermediates in important electrochemical reaction systems. Nanoelectrodes modified with bi-metallic (i.e. electrocatalyst) nanoparticles will be investigated as sensitive electrochemical probes, e.g. for fundamental electrocatalytic studies of single catalyst nanoparticles or for in-situ probing in electro-chemical reactors. Such studies are highly important to advance fundamental understanding of electrocatalytic generation of renewable energy vectors, such as hydrogen and methane. The functional nanosensors will be integrated into a simple electrochemical reactor system and tested for in-situ sensing during electro-catalysis, including electrocatalytic CO2 reduction and hydrogen evolution reaction.