Quartz crystal microbalance and electrochemical cytosensing on a chitosan/multiwalled carbon nanotubes/Au electrode

The piezoelectric quartz crystal microbalance (QCM) was used to monitor the adhesion of mammalian cells on a chitosan (CS)/multiwalled carbon nanotubes (MWCNTs) composite modified gold electrode. The morphology and chemical properties of the CS/MWCNTs film were characterized with scanning electron microscopy (SEM) and Fourier transform infrared (FT-IR) spectroscopy. The human breast cancer cells (MCF-7) were adhered to and grown on the CS/MWCNTs film modified gold surface or a net CS film modified gold surface, and the process of which was continuously monitored and displayed by changes of the resonant frequency (Δf0) and the motional resistance (ΔR1) of the QCM. The attachment/spreading process of the MCF-7 cells on the QCM Au electrode decreased the Δf0 and increased the ΔR1 simultaneously, implying rather complicated effects (simultaneous mass, viscoelasticity and probable surface-stress load) on the sensor surface. The attachment rate and viability of the cells when proliferating on the two surfaces were detected by the MTT assay. The presence and state of cells on the electrode surface were confirmed by the fluorescent microscopy. Cyclic voltammetry and electrochemical impedance spectroscopy of the ferricyanide/ferrocyanide couple were examined before and after the cell adhesion. All data showed that the cell adhesion and proliferation processes were more efficient on the biocompatiable nanocomposite surfaces. The cell-based biosensor has potential for identification and screening of biologically active drugs and other biomolecules affecting cellular shape and attachment.