Multi-Analyte Biosensing with Enzymatic Electrochemical Sensors

<p>Researchers have integrated electrochemical biosensor arrays into microfluidic cell culture platforms for measuring metabolic markers, proteins, and nucleic acids. There is a gap for a multi-analyte electrochemical biosensor lab on a chip for simultaneous metabolic monitoring and functional sensing of neurotransmitters, such as glutamate and dopamine. This lab on a chip should also be compatible with optical sensing, such as recombinant fluorescent neurotransmitter and epigenetic biosensors. A microfluidic neuronal cell-culture platform with these capabilities would be a valuable tool for quantifying phenotype changes of patient-specific human induced pluripotent stem cells resulting from environmental chemical exposure. To this end, we leveraged methods of rapid prototyping and multiplexed biorecognition element (enzyme) immobilization to develop stable and selective arrays of enzymatic electrochemical sensors for multi-analyte biosensing of glucose, lactate, and glutamate.</p> <p><br></p> <p>Chapter 1 is an introduction, reviewing electrochemical sensing of neurotransmitters and microfluidic electrochemical systems for metabolic monitoring (microphysiometry). Chapter 2 describes the application of direct writing of conductive Pt-based inks to the fabrication of multi-analyte glucose/lactate/glutamate biosensor arrays on glass and flexible substrates. We demonstrated these biosensor arrays by measuring glucose/glutamate uptake and lactate release in situ from astrocyte cultures. Chapter 3 describes the translation of 2-aminophenol electropolymerization for multiplexed enzyme immobilization (glucose/lactate/L-glutamate oxidase) from stereo microwires to microelectrode arrays. Chapter 4 describes embedding a glutamate sensor array into a transparent microfluidic lab on a chip for neurotoxicity research. We validated this system by measuring changes to glutamate uptake by glutaminergic neurons following treatments with environmental chemical toxins methylmercury and manganese.</p> <p><br></p> <p>We have developed sensors using direct ink writing robotic printing and conventional thin film processing that can simultaneously measure neurotransmitters (glutamate) and metabolic biomarkers (glucose and lactate) together simultaneously in cell culture media. We have shown biocompatibility and stability of these sensors for days to over a week in neuronal cell culture. This work has brought us closer to a multimodal brain on a chip, incorporating extracellular electrochemical sensors and intracellular optical sensors. Future work will validate simultaneous multimodal sensing and then apply it to identifying susceptibility to neurodegenerative diseases from patient-derived stem cells.</p>