Nanoelectrochemical Techniques for Single Cell and Spheroid Metabolomics and Pharmacokinetics

Purdue University, West Lafayette IN

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Abstract

Tissue is extraordinarily complex, and new measurement tools are necessary to elucidate cellular function and composition at never-before-observed levels. The long-term goal of this research program is to develop nanoelectrochemical technologies for single cell and spheroid function and composition. The main focus will be on metabolomics (quantifying several metabolites simultaneously) and pharmacokinetics (quantifying analyte concentrations with time). We endeavor to make the most accurate measurements of cellular metabolites with sub- micrometer resolution while minimally perturbing cellular homeostasis. These measurements have the potential to open the door to unrealized sensitivity in sub-cellular metabolite quantification. Electrochemistry at nanoelectrodes has been used to interrogate cellular processes and quantify reactive species within cells. However, the amount of charge required to make an electrochemical determination can be detrimental to a cell, which comprises a rather small volume, within 100 milliseconds. Therefore, novel techniques must be developed to minimize the perturbation to cellular homeostasis to ensure accurate measurements of natural cellular processes. To achieve low-charge electroanalysis, our group has innovated novel potentiometric and aptamer-based sensing modalities. Over the next five years, metabolite- specific sensors will be miniaturized to the sub-micrometer scale for single cell and spheroid analyses. Multibarrel nanoelectrodes will be developed and optimized to quantify several metabolites in single cells and spheroids with high spatiotemporal resolution. These sensors will be deployed into single cells and spheroids for metabolomics and pharmacokinetics studies. Findings will be validated with microscopy and mass spectrometry. Finally, the sensing modalities will be extended to build onto a new bioimaging platform: the Hyperspectral-Assisted Scanning Electrochemical Microscope, a low-cost alternative to white light laser confocal microscopy. The overarching goal of this research program is to create the foundation for generalized metabolomics studies with nanoelectrode sensors, where the library of metabolites of interest depends only on the availability of an enzyme or a carefully designed aptamer.