In Situ Partial Treatment of Single Cells by Laminar Flow in the "Open Space"

Regional difference of a single cell is nonignorable, which means it is not precise to investigate the single cell as a homogeneous object. A convenient method to investigate cellular response to the treatment at the subcellular level is still needed. In this work, we developed a microfluidic approach for manipulating a partial region of a single adherent cell by generating a stable distribution of microenvironments. By controlling flow rates and the gap between the probe and substrate, the diffusion effect can be adjusted as needed. Distribution of the solute was revealed by fluorescein, demonstrating the stability of the interface between two miscible fluids. Partial lysis of single cells (Caco-2, MCF-7, U87 cells) was successfully performed, and partial staining (Mito-Tracker Green FM, Mito-Tracker Red CMXRos, ER-Tracker Green) of a single cell (U87) was explored. Self-healing and regeneration of a single U87 cell after partial lysis was also observed. All of those results demonstrated the feasibility and significance of our idea. The method would be a promising tool for further single-cell analysis and subcellular research.