Real-time monitoring of cellular events using capacitance-based sensors

Abstract

We measured chemosensitivity of doxorubicin for 8-different cell lines using 16 well capacitance-based sensor arrays, and compared the results with MTT assay which is one of the widely used methods for chemosensitivity. The MTT assay uses the biochemical reaction of live cells, but the capacitance-based sensors use the electrical property which is sensitive to morphology and physiology of cells. For the direct comparison, the capacitance data was converted to similar form with MTT assay. This data show very similar behavior to MTT assay. To increase the electrode thickness, we made the capacitance sensor have 3-dimensional structure using 4 μm-long vertically aligned CNTs. These sensors detected the capacitance increment during cell doubling events and monitored the proliferation and death of Jurkat cells which cannot be observed using the gold capacitor. Finally, we monitored the internalization of Au nanoparticles with various concentration and different shapes. When the Au nanoparticles internalized in cells, the capacitance exhibited the dip. This capacitance dip appeared more clearly when the concentration of Au nanoparticles was higher and the shape of Au nanoparticle had lower aspect ratio. These results suggest that the Au nanoparticles with spherical shape have higher probability of cell internalization. The capacitance-based sensor will be promising cell-based biosensor because of their good properties such as low cost, simple procedure, real-time monitoring. It can be used for development of drugs and investigation of cellular events.