Microfluidic Impedance-Metric Biosensor for Monitoring Carbon Nanotube-Induced Epithelial Permeability

Z. Huang, N. Wu, Y. Rojanasakul, Y. Liu
West Virginia University, US

Keywords: microfluidics, impedance, biosensing, nanotoxicity

Summary:

We have developed a microfluidic impedance-metric biosensor for investigation of multi-walled CNTs (MWCNTs) effects on the cultured monolayer of human lung epithelial cells. The biosensor consists of a transparent porous polyester cell-culture membrane embedded with a double-layer poly(dimethylsiloxane) (PDMS) microfluidic channels. Two electrodes can be easily inserted to the biosensors for impedance measurements. Experimental results showed that human lung epithelial cells can form a monolayer within 10 days culture inside the device. Immunofluorescence staining characterization confirmed the formation of tight junction proteins in the monolayer, indicating that an in vitro model of human lung epithelium was successfully created in the biosensor. During the formation of the tight epithelial monolayer, the electrical impedance spectra were obtained by applying an alternating current at frequencies scanning from 0.1 Hz to 1 MHz. The normalized transepithelial electrical resistance (TEER) values showed that the resistance increased with days of culture until a relative constant value was observed, which matched with the Calu-3 TEER results obtained from conventional Transwell system. The biosensor is potable, low cost, no chemical targeting required and capable of real-time and accurate monitoring compared to previous models for studying epithelial permeability.