Measurement of Tryptophan in Cell Cultures Using Fast Scan Cyclic Voltammetry at Carbon Fiber Microelectrodes with Improved Sensitivity and Selectivity

Establishing a sensitive and selective method to measure tryptophan in situ with good spatiotemporal resolution is invaluable to understanding its biological role and activity in nutrition, health, brain disorders, and the gut-brain axis. Here, we report on a sensitive and selective method to measure tryptophan over its main interfering species tyrosine. Specifically, we achieve this using fast scan cyclic voltammetry at carbon fiber microelectrodes via the application of an optimized multi-scan rate sawhorse waveform. We report over four-fold increase in sensitivity over previously reported methods and a six-fold selectivity of tryptophan quantitation over that of tyrosine. We demonstrate the utility of our method via measuring extracellular Trp in cultured PC-12 cells and PC-12 cells with overexpressed tryptophan hydroxylase 2.