Sensitive Detection of Single-Cell Secreted H₂O₂ by Integrating a Microfluidic Droplet Sensor and Au Nanoclusters

Abstract

As an important signaling molecule, hydrogen peroxide (H₂O₂) secreted externally by the cells influences cell migration, immunity generation, and cellular communications. Herein, we have developed a microfluidic approach with droplets in combination with Au nanoclusters for the sensitive detection of H₂O₂ secreted by a single cell. Isolated in the ultrasmall volume (4.2 nL) of a microdroplet, single-cell secreted H₂O₂ can initiate dramatic fluorescence changes of horseradish peroxidase-Au nanoclusters. We have demonstrated an ultrahigh sensitivity (200-400 attomole H₂O₂ directly measured from a single cell) with good specificity. It offers a useful research tool to study the cell-to-cell differences of H₂O₂ secretion at the single-cell level.