On-Chip Cell-Cell Interaction Monitoring at Single-Cell Level by Efficient Immobilization of Multiple Cells in Adjustable Quantities

In recent decades, cell immobilization using microfluidic chips has facilitated significant advancements in biological analyses at the single-cell level. However, the efficient capture of multiple cells as a cluster in adjustable quantities for cell-cell interaction has not been achieved. In this paper, aiming to monitor the cell-cell interaction at the single-cell level, we proposed a novel method for the efficient immobilization of adjustable quantities of cells on the basis of passive hydrodynamics so that different cell-cell interaction patterns could be generated. Experiments were conducted to characterize the key geometric parameters of the chip to optimize the efficiency of trapping different quantities of cells. In the microfluidic chips optimized for immobilizing one to five cells, the trapping success rates (TSRs) were up to 97%, 87%, 84%, 58%, and 54%, respectively. Furthermore, the throughput was over 200 cells min-1 with a minimum cell density of 350 cells mm-2. Finally, in the experiments of applying the proposed multicell immobilization chips to cell-cell interaction monitoring, calcein-AM transfer between multiple cells under different patterns has been studied through quantifying the local fluorescent intensity. The results demonstrated that the proposed method could be a promising opportunity in the widening field of biological research at the single-cell level.