An innovative rotational magnetic system to enhance cell transfection with magnetic nanoparticles

Abstract

The use of nanoparticles combined with magnetic fields has gained in importance in medical diagnosis and therapy over the last years. It has also contributed to the improvement of pharmaceutical research and biological methods [6]. In fact, researchers are not only able to target cells with active agents bound to magnetic nanoparticles that are controlled and guided by external magnetic fields, but they also can enhance reproducibly the rate of cell transfection by coating magnetically activated nanoparticles with DNA and pulling the resulting complex through the cell membrane to the inner parts of different kinds of cells. This technique is used to produce proteins for clinical or research applications, to add genetic markers to cell lines and more generally to study DNA replication, recombination and mutation. For this application, mainly static magnetic fields have been used, whereas new experiments suggest the use of pulsing fields, with a certain amplitude and a certain frequency, to best improve the transfection rate. Using fields that change over time necessitates strong electromagnets that are specially conceived for the transient application and really demand a sophisticated design and a strict temperature control due to the emerging eddy currents [3]. These cause a heating of the system that not only leads to instabilities in the resulting magnetic field and the overall experimental parameters but also represents a disturbing factor for the activity of the treated cells and even a danger for their viability. We developed a new system that delivers the needed field characteristics without using electromagnets and therefore excludes their drawbacks and limitations. As a matter of fact, we conceived a new rotational permanent magnet system based on a brush-less motor that assures the exposure of the magnetic nanoparticles to well defined pulses, which should enhance the efficiency of cell transfection independently of electromagnets' considerations. Moreover, not only adherent cell cultures can be targeted by the elaborated system, also cells in suspension are easily exposed to the necessary magnetic pulses in the designed setup. © 2009 Springer-Verlag.