Cell based biosensors are analytical measurement devices which use mammalian cells as the sensing element. The response of the cells provides an understanding of the effects of the analyte at a physiological level. Electric Cell-substrate Impedance Sensing provides an emerging powerful method to perform real time cell monitoring without the use of radioactive tracers, or biological markers.
It has long been acknowledged that the phospholipid bilayer of the plasma membrane possesses dielectric properties. Culturing cells over electrode contacts and measuring changes in the effective electrode impedance offers a non-invasive assay to determine the adhesion, spreading, and motility of a cultured cell line. Impedance measurements are centered on the fact that whole live cells, at low signal frequencies, are excellent electrical insulators. Cell growth and migration leading to increased coverage of an electrode surface result in increased electrode impedance.
Upon exposure to a substance which adversely affects their health, adherent cells will detach from the electrode surface. A change in impedance value is therefore seen to be directly related to attachment and spreading of cells on the surface of the electrodes. These changes in impedance values can be used to explain cell behaviour and to test for new drug substances.
Monitoring cytotoxicity with high sensitivity, rapidly, in parallel with a multi-sensing function, at low cost and in the field, is of great interest in the fields of clinical diagnostics, environmental monitoring, food safety and security. This is important because there is a demand for a higher standard of validated in vitro cytotoxicity test assays and technologies based on the need for greater accuracy and reliability from both a regulatory and industrial perspective. There is an existing gap in the market between animal and validated in vitro assays due to new regulations for the testing and approval of chemicals.
There is also considerable demand from pharmaceutical, cosmetics and chemical companies for new more reliable validated in vitro test methods and technologies. Companies are also committed to introducing in vitro toxicity testing earlier in their discovery and development processes to contain costs and to reduce the attrition rates of pre-clinical and clinical testing due to toxicity concerns.