Microfabricated Flow System for Magnetic Cell and Particle Separation

Abstract

A new microchannel-based system for continuous separation of magnetizable particles is presented, with possible applications in cell and particle separation, immunoassays, receptor assays or affinity purification. The presented system offers the novel possibility to handle, entrap and sort small volumes of cell samples in a continuous or stopped-flow regime. By using a microfabricated flow chip with integrated permanent or electromagnets, magnetizable particles can be sorted in a one-step procedure. The magnetic field does not have to be removed and no washing steps are necessary. The microchannels of the flow chip are etched into silicon and covered with a transparent glass plate, allowing external optical observation and detection of the liquids inside the microchannels using a microscope. In that respect the optomagnetic flow cytometry system combines both optical characterization of cells or particles and magnetic separation. An apparatus for magnetic separation including a system of valves, syringe pumps and the flow chip has been designed and used for initial experiments. The simply equipped and portable sorting system has been automated for magnetic particle separation. The suitability of the flow chip was demonstrated by the separation of paramagnetic particles and living cells. Enrichment rates of more than 300-fold can be achieved.