Application of a nanotip array-based electrochemical sensing platform for detection of indole derivatives as key indicators of gut microbiota health

Abstract

The human gut microbiota plays a vital role in health and disease. Indole derivatives like indole, tryptamine and indoxyl sulfate represent important microbiota-associated metabolites and biomarkers of gut function. However, current techniques for analysis of these metabolites like mass spectrometry and HPLC suffer from limitations including high cost, complex sample preparation procedures, and long analysis times. In contrast, electrochemical sensing offers a rapid, simple and low-cost alternative with potential for point-of-care applications. We report a nanotip array-based electrochemical sensing platform for rapid, simple and sensitive quantification of indole derivatives. Silicon nanotip arrays were fabricated with controlled sub-micron morphology and coated with gold to form nanotip electrodes. Further modification with silver nanoparticles (AgNPs) led to significantly enhanced electrochemical signal. Using differential pulse voltammetry (DPV), distinct oxidation peaks were observed for indole, tryptamine and indoxyl sulfate, enabling sensitive detection down to nM levels. A broad linear dynamic range of 7 orders of magnitude demonstrated excellent quantitative capabilities. The sensor showed high reproducibility (<5 % RSD) and selectivity for the metabolites in the presence of potential interferents. Importantly, accurate detection of spiked indole derivatives was achieved in complex biological samples like serum and fecal extracts. The capacity to rapidly quantify indole derivatives in minimally processed samples highlights the potential of this nanotip electrochemical sensing strategy for point-of-care analysis of microbiota function. Overall, this work provides a robust nanotechnology-enabled platform for metabolite profiling to elucidate microbiota health and disease.