Work packages 1 (WP1) and 4 (WP4) tie into key scientific objectives I above, where the Fellow made significant progress towards pushing the spatial resolution of SEPM techniques and increasing the density of information acquired. The Fellow developed a new and unique method to cross calibrate fabrication procedures which enables worldwide reproducibility of fabrication procedures and a more in-depth understanding of the fabrication parameters used. Details of this work will be submitted to publication soon, as a technical note, to Analytical Chemistry.
The Fellow also developed new ways to fabricate the smallest electrode, relying on electrochemical deposition and bipolar electrochemistry. This work was performed with a PhD students and the preliminar results obtained are described in a chapter of his thesis.
Following this work, the Fellow, working with the same PhD, developed a new SEPM technique, relying on local conductivity and SECM measurements for accessing topography, local conductivity and chemical activity of substrates with nanometre lateral spatial resolution, pushing the limits of spatial resolution and density of information acquired by SEPM techniques beyond the state-of-the-art.The technological development nature of this WP and key scientific objective required the Fellow to develop new tools and techniques to fabricate SEPM probes and to adapt existing instrumentation for new applications. Many of the new tools were developed using 3D printing The Fellow produced a feature article on the importance and application of 3D printing in research laboratories. the manuscript is currently under review. Finally, the progress made towards WP1 resulted in the publication of a review article about high-resolution SEPM techniques.
Work package 2 (WP2) ties into key scientific objectives II above, where the Fellow made significant progress in understanding the relation between surface charge and cellular function/structure. SICM was used to investigate the local charge environment around single bacterial cells and spores and finite element method (FEM) models were used to convert SICM currents to surface charge values. During the development of the project it became clear that the SICM tip could interact with the sample more than previously assumed and current FEM models were too simplistic to allow this interaction to be studied. Together with several PhD students, the Fellow developed a new and more comprehensive FEM model utilizing true biological descriptors of the cell. A manuscript describing the work is currently under review.
Work package 3 (WP3) ties into key scientific objectives III above, where the Fellow made significant advances in investigating cellular and tissue metabolism by probing the local consumption of molecular oxygen by living samples using SECM. The oxygen consumption rate (OCR) is a proxy for local metabolic function and was used to access tissue-specific metabolic activity in nematodes under basal conditions and when chemically and genetically challenged. The Fellow, developed a measuring protocol allowing high-throughput electrochemical measurements of biological samples and a comprehensive FEM model of the system, which allowed local OCRs to be calculated. This study is the first to report space-resolved local OCRs which are commonly accessed at the (large) sample-level. These conventional (traditional) measurements are blind to local – subtle- differences in metabolic activity. A manuscript, describing the findings and methods is currently under review.
