Patterning of magnetic nanobeads on surfaces by poly(dimethylsiloxane) stamps

Poly(dimethylsiloxane) (PDMS) stamps are widely used in soft lithographic methods. They are powerful tools for obtaining structures of soft material in the micrometer to nanometer range by printing techniques. In this contribution, a new application of h-PDMS stamps for nanobead deposition is introduced. Magnetite-polysaccharide particles of an average diameter of 150 nm are used. They can be biologically functionalized by attaching various molecular groups. Deposition of these particles on a carrier substrate results in well-reproducible structures. This is achieved by means of PDMS stamps with different patterns using a microfluidic approach on one hand and a printing approach on the other hand. Furthermore, magnetic substrates with particular domain structures have been used. The beads can then be arranged in rather complicated but well-defined geometrical structures along the domain walls. The magnetic interaction considerably increases the adhesion of the beads to the carrier substrate. All involved materials are biocompatible. Thus the setup can be used in cell culture experiments in order to investigate influences of different particle-bound proteins and particle patterns on cell growth and vitality.