Characterization of planar concentration gradients in a sequential-injection system for cell-perfusion studies

Abstract

This paper describes the characterization of a perfusion chamber that is coupled with a sequential-injection system and is being designed for live-cell perfusion. The apparatus consists of a multi-port valve, a peristaltic pump, a perfusion chamber and an epifluorescence microscope. The entire system is computer controlled and temperature regulated. The parameters discussed are the concentration–time profiles with regard to the volume of reagent used and the position of the cell in the perfusion chamber. Other parameters discussed include the stopped-flow compliance, reproducibility and symmetry of the concentration gradients formed. The system is shown to be suitable for two modes of perfusion; the first in which all cells are exposed to the same concentration of reagent, and the second in which cells are exposed to a gradient of concentrations. All characterization is performed with use of bulk fluorescein as a tracer, and a correlation is made between the bulk flow and the response within the cellular environment by using 5-[N-(octadecanoyl)amino]fluorescein.