Label-Free Imaging of Cell Apoptosis by a Light-Addressable Electrochemical Sensor.

Label-free electrochemical visualization of cancer cell apoptosis is essential for cancer therapies. In this work, we proposed a noninvasive imaging method using a light-addressable electrochemical sensor (LAES) for label-free imaging of drug-induced tumor cell apoptosis. The dynamic AC photocurrent changes on MCF-7 human breast adenocarcinoma cells after inducing by tamoxifen were imaged. And the reasons for photocurrent changes on the cells were explored by monitoring the changes in the ζ potentials of cells and Faradic impedance. The results demonstrated that the AC photocurrent on apoptotic MCF-7 cells increased, and the apoptosis degree of each cell was heterogeneous. Moreover, the AC photocurrent increase was attributed to the increased cell membrane permeability and the increased gap between the cell basal surface and the substrate caused by cell apoptosis. This study provides a brand new approach for label-free visualizing cell apoptosis heterogeneity, which has great potential in apoptosis-associated drug screening or drug efficacy evaluation.