Cellular impedance sensing combined with LAPS as a new means for real-time monitoring cell growth and metabolism

• Cell growth and metabolism were continuously and synchronously monitored by cellular impedance sensing and LAPS based on the same sensor structure.
• Electrolyte-insulator-semiconductor (EIS) structure was used as the sensor structure.
• Equivalent circuit model for cellular impedance sensing was build.
• Cytotoxicity of heavy metal Cadmium (Cd) was evaluated.

Light-addressable potentiometric sensor (LAPS) can be used as a sensitive pH-meter with its electrolyte-insulator-semiconductor (EIS) structure. Previous LAPS practices in cell-based assays, which were limited to pH detection of extracellular microenvironment, seemed to be insufficient since the cell physiology is reflected by various parameters, such as energy metabolism and cell morphology. In this paper, the feasibility of monitoring cell growth status based on the same sensor structure of LAPS was investigated and testified. A novel real-time biosensor system was established, which could monitor the cell growth and metabolism synchronously. In the cellular experiment, the normal growth of mouse embryonic fibroblast 3T6 cells and their apoptosis in the presence of heavy metal cadmium (Cd) were investigated. The results showed that the normal growth of cells could lead to an increase of 2.65 in cell index (CI). And, CI decreased from 1.96 in normal growth condition to 0.64 24 h after the treatment of Cd and fell to 0.16 after 48 h. The extracellular acidification rate (ECAR) experienced a similar change to CI. The combination of cellular impedance sensing with LAPS will bring out new opportunities for LAPS to be more utility in cell-based assays, such as cytotoxicity detection and drug evaluation.