| The rapid development of biomedical sciences requires a great amount of biological experiments on in vitro cell culture in which the cellular responses are the major subject to be studied. Among various parameters of cellular responses, cell adhesion is one of the most critical since it regulates multiple subsequent cell behaviors such as growth, death and proliferation. The monitoring of cell adhesion change is therefore expected to enable the detection of cellular responses. In the present work, a real-time, impedance-sensing method is developed that accurately monitors equivalent cell-substrate distance, which is a direct indicator of cell adhesion. This method has been employed to study cardiomyocyte culture and demonstrated the ability to detect cell death.;The planar impedance sensors have been created with microfabrication processes to measure the impedance of certain electrode/electrolyte interface. Cyclic spectrum measurements of working electrode impedance are carried out and automatically fit into the equivalent circuit model, which is established using electrochemical impedance spectroscopy (EIS). The data are displayed as the alteration of normalized cell-substrate distance and the essential parameters for manual calculation of absolute cell-substrate distance with electric cell-substrate impedance sensing (ECIS). The combination of these two results offers a time course of equivalent cell-substrate distance.;The as-described impedance-sensing method has been applied to detect cardiomyocyte death induced by tumor necrosis factor-alpha (TNF-alpha). The cell detachment is detected with our assay and proved related to cell death in the following experiments, indicating its advantage against the conventional assays, such as Trypan blue exclusion. Furthermore, considering cell detachment is an early morphological evidence of cell death, we remove TNF-alpha from the cardiomyocyte culture before the transition to achieve the intervention of cellular responses.;This work also includes development of transparent impedance sensors which enables the optical observation. It adds to the previously described impedance-sensing method to provide a complementary set of monitoring technologies for cellular responses. |
