Electrochemical (bio-)sensors operating in human physiological fluids

Sammanfattning: This thesis is focused on developing electrochemical (bio-)sensors specifically designed to detect biomolecules and bacteria in human physiological fluids. A more comprehensive understanding of their performance can be obtained by exposing the sensors to real human physiological fluids. Thus, four biosensors were designed and tested in saliva, plasma, blood, and urine. Specifically, a voltammetric electronic tongue, integrating six different electrode materials, was developed to qualitatively assess SARS-CoV-2 in saliva samples using principal component analysis. A tubular enzyme-based sensor utilizing incorporated cellobiose dehydrogenase in an Os(bpy)PVI redox polymer was employed for continuous glucose sensing in human plasma and undiluted whole blood under homeostatic conditions. Two different sensing concepts were developed for the label-free detection of bacteria (Escherichia coli, Enterococcus faecalis, and Klebsiella pneumoniae) in artificial urine and human urine based on metabolic activity due to bacterial growth. The first sensor enabled continuous bacterial detection by reducing Prussian Blue deposited on screen-printed electrodes with wireless data transfer. The second bacterial-sensitive sensor utilized electrochemical characterization to identify three bacteria types based on artificial urine metabolic changes. For a qualitative investigation of the metabolic changes, nuclear magnetic resonance was utilized, and flow cytometry was used to quantify and correlate bacterial growth with electrochemistry. Multivariate statistical data analysis was applied to distinguish bacteria-free and bacteria-infected artificial urine. Finally, an overview of the recent advances in the field of non-invasive electrochemical biosensors operating in secreted human physiological fluids, viz., tears, sweat, saliva, and urine, was give