Semiconductor Transistor-Based Detection of Epithelial-Mesenchymal Transition via Weak Acid-Induced Proton Perturbation

Developing new detection methods for the epithelial-mesenchymal transition (EMT), where epithelial cells acquire mesenchymal traits, is crucial for understanding tissue development, cancer invasion, and metastasis. Conventional <i>in vitro</i> EMT evaluation methods like permeability measurements are time-consuming and low-throughput, while the transepithelial electrical resistance measurements struggle to differentiate between cell membrane damage and tight junction (TJ) loss and are affected by cell proliferation. In this study, we developed a pH perturbation method to detect TJ barrier disruption during epithelial EMT by sensing proton leakage induced by a weak acid using a pH-responsive semiconductor. Mardin-Darby canine kidney (MDCK) epithelial cell sheets cultured on an ion-sensitive field effect transistor's gate insulator were induced into EMT by exposure to the cytokine transforming growth factor-β1 (TGF-β). Our pH perturbation method successfully detected EMT in MDCK sheets at a TGF-β concentration one-tenth of that required for conventional methods. The high sensitivity and selectivity arise from using minimal protons as indicators of TJ barrier disruption. TGF-β-induced EMT detection results using our method align with EMT-related gene and protein expression data. In drug screening with EMT inhibitors, this novel method showed similar trends to conventional ones. The pH perturbation method enables highly sensitive, real-time EMT detection, contributing to elucidating biological phenomena and pharmaceutical development.