Microfluidic-based measurements of cytochrome P450 enzyme activity of primary mammalian hepatocytes.

A microfluidic-based system was developed for the in situ monitoring of the 7-ethoxyresorufin O-dealkylation (EROD) activity of primary rat hepatocytes by measuring the fluorescent intensity of both cells and their surrounding media. The microfluidic chip was designed to allow the cell suspension and test reagent to be introduced in a layer-by-layer flow format, thereby resulting in a short mixing time by diffusion. A good linear relationship was obtained between the resorufin concentration up to 30 microM and fluorescent intensity over the chip's circular chamber area. The EROD activity was determined with 3-methylcholanthrene (3-MC)-induced hepatocytes. The inhibition effect of alpha-naphthoflavone was also examined on EROD activity resulting in an IC(50) value of 12.98 microM.