Forum for Science, Industry and Business

Sponsored by:     3M 
Search our Site:


'Premium Vectors' for the Life Sciences: Magnetic Nanoparticles

Positively charged star polymers containing a magnetic core are particularly suitable as DNA-delivery vectors.
They show extremely high gene transfer efficiency and afterwards enable the quick and simple separation of the transfected cells from the transfection pool. A research team from the University of Bayreuth reports this result in the current online edition of "Biomacromolecules".

Only five months ago a research team from the University of Bayreuth reported a discovery that was internationally acknowledged. The scientists led by Prof. Dr. Ruth Freitag (Process Biotechnology) and Prof. Dr. Axel Müller (Macromolecular Chemistry II) developed large star-shaped polymers that are promising vectors in genetic engineering. Most importantly, the new polymers were capable of introducing genes into a large variety of living cells, including non-dividing and differentiated cells, i.e. cells that up to now typically require viruses for efficient genetic modification. In chemical terms, these molecules can be described as PDMAEMA stars.

Now the Bayreuth team reports a related discovery in the current online edition of "Biomacromolecules". As the team specifies, similar PDMAEMA stars can be constructed with a magnetic core and then combine the ability for efficient transfection with the potential for easy separation of the transfected from the non-transfected cells. This research success stems from an intensive interdisciplinary cooperation of long standing. The magnetic PDMAEMA stars were produced in the Bayreuth polymer chemistry laboratories. Tests in the Biotechnology group then demonstrated that the novel agents may very well constitute 'premium vectors' for the genetic modification of cells.

Biotechnological advantages: high transfection efficiency,
quick and simple isolation of transfected cells

Like the PDMAEMA stars previously tested, the magnetic PDMAEMA stars are also capable of efficiently introducing genetic information, i.e. DNA molecules, into living cells, a process called transfection. "When we transfected cells of a cell line originating from the Chinese hamster (CHO cells), we consistently observed transfection efficiencies that largely exceed those we previously obtained using poly(ethylenimine) (PEI)", explains Prof. Dr. Ruth Freitag. Linear PEI has until now been regarded as the 'gold standard' in cell transfection and is therefore used in genetic engineering processes worldwide.

The new vectors have another advantage in addition to their unusual efficiency. The PDMAEMA stars retain their magnetic properties when they are within the cells. For this reason, the transfected cells can be separated from all other cells in a very simple manner: a standard strong magnet is sufficient to extract specifically the cells that have taken up the DNA from those that have not. This makes the magnetic PDMAEMA stars the ideal tool to extract successfully transfected cells from the general transfection pool, and thereby prepare in pure form, a genetically modified cell population, be it to introduce a new gene, compensate for a missing gene, to substitute a defect genes or to ameliorate the consequences of such aberrations.

Star-shaped giant molecules containing a magnetic core,
synthesis using modern polymer chemistry techniques

How are the magnetic PDMAEMA stars produced? Spherical nanoparticles are the starting point of this process. They belong to the class of iron oxides and have magnetic qualities. Initiator molecules are attached to the surface of such a particle, forming the starting points for the star-shaped structure. Each initiator starts the polymerisation of a long PDMAEMA chain, an 'arm'. This process (called "grafting from") makes the spherical nanoparticle the centre of a large star-shaped molecule. When it is finished, the star-shaped molecule has on average 46 of these chain-like arms. Each arm contains nearly 600 repeating molecule groups.

Patent registration

On account of the high application potential for the life sciences, the magnetic PDMAEMA stars have been registered as a patent in the name of the University of Bayreuth by the Bavarian Patent Alliance (BayPAT, the central patent and marketing agency of the Bavarian universities). The Innovation Advisory Service of Bayreuth University, in particular Dr. Andreas Kokott und Dr. Heinz-Walter Ludwigs, made a major contribution to the preparation for the patent registration.


Alexander P. Majewski, Anja Schallon, Valérie Jérôme, Ruth Freitag, Axel H. E. Müller, and Holger Schmalz,
Dual-Responsive Magnetic Core-Shell Nanoparticles for Non-Viral Gene Delivery and Cell Separation,
in: Biomacromolecules, Publication Date (Web): Feb 1, 2012
DOI: 10.1021/bm2017756
For suitability of PDMAEMA stars in genetic therapy see also:
Contact for further information:
Prof. Dr. Ruth Freitag
Department of Process Biotechnology
University of Bayreuth
95440 Bayreuth, Germany
Tel.: +49 (0)921 55-7371
Prof. Dr. Axel Müller
Department of Macromolecular Chemistry II
University of Bayreuth
95440 Bayreuth, Germany
Tel.: +49 (0)921 55-3399

Christian Wißler | Universität Bayreuth
Further information:

More articles from Life Sciences:

nachricht First time-lapse footage of cell activity during limb regeneration
25.10.2016 | eLife

nachricht Phenotype at the push of a button
25.10.2016 | Institut für Pflanzenbiochemie

All articles from Life Sciences >>>

The most recent press releases about innovation >>>

Die letzten 5 Focus-News des innovations-reports im Überblick:

Im Focus: Etching Microstructures with Lasers

Ultrafast lasers have introduced new possibilities in engraving ultrafine structures, and scientists are now also investigating how to use them to etch microstructures into thin glass. There are possible applications in analytics (lab on a chip) and especially in electronics and the consumer sector, where great interest has been shown.

This new method was born of a surprising phenomenon: irradiating glass in a particular way with an ultrafast laser has the effect of making the glass up to a...

Im Focus: Light-driven atomic rotations excite magnetic waves

Terahertz excitation of selected crystal vibrations leads to an effective magnetic field that drives coherent spin motion

Controlling functional properties by light is one of the grand goals in modern condensed matter physics and materials science. A new study now demonstrates how...

Im Focus: New 3-D wiring technique brings scalable quantum computers closer to reality

Researchers from the Institute for Quantum Computing (IQC) at the University of Waterloo led the development of a new extensible wiring technique capable of controlling superconducting quantum bits, representing a significant step towards to the realization of a scalable quantum computer.

"The quantum socket is a wiring method that uses three-dimensional wires based on spring-loaded pins to address individual qubits," said Jeremy Béjanin, a PhD...

Im Focus: Scientists develop a semiconductor nanocomposite material that moves in response to light

In a paper in Scientific Reports, a research team at Worcester Polytechnic Institute describes a novel light-activated phenomenon that could become the basis for applications as diverse as microscopic robotic grippers and more efficient solar cells.

A research team at Worcester Polytechnic Institute (WPI) has developed a revolutionary, light-activated semiconductor nanocomposite material that can be used...

Im Focus: Diamonds aren't forever: Sandia, Harvard team create first quantum computer bridge

By forcefully embedding two silicon atoms in a diamond matrix, Sandia researchers have demonstrated for the first time on a single chip all the components needed to create a quantum bridge to link quantum computers together.

"People have already built small quantum computers," says Sandia researcher Ryan Camacho. "Maybe the first useful one won't be a single giant quantum computer...

All Focus news of the innovation-report >>>



Event News

#IC2S2: When Social Science meets Computer Science - GESIS will host the IC2S2 conference 2017

14.10.2016 | Event News

Agricultural Trade Developments and Potentials in Central Asia and the South Caucasus

14.10.2016 | Event News

World Health Summit – Day Three: A Call to Action

12.10.2016 | Event News

Latest News

Ice shelf vibrations cause unusual waves in Antarctic atmosphere

25.10.2016 | Earth Sciences

Fluorescent holography: Upending the world of biological imaging

25.10.2016 | Power and Electrical Engineering

Etching Microstructures with Lasers

25.10.2016 | Process Engineering

More VideoLinks >>>