Magnetic nanostructures for on-chip manipulation of biological entities and biosensing

In this paper we present recent results obtained in the Nanobiotechnology and Spintronics group of  the LNEES research center of Politecnico di Milano, partially in cooperation with the nanoGUNE center in Spain, in the field of lab-on-chip devices based on magnetic nanostructures.

Manipulation of biological entities:

A few years ago the LNESS group discovered, in cooperation with nanoGUNE, that the controlled propagation of constrained magnetic domain walls (DWs)  in magnetic stripes can be used for finely manipulating magnetic particles in suspension over them. This approach relies on the precise control of the motion of DWs that can be achieved in ferromagnetic stripes (magnetic conduits) [1] and on the robust coupling between a DW and a magnetic particle in suspension over the conduits.[2] In this way the injection, displacement, and annihilation of a single DW in a ferromagnetic stripe results in the capture, displacement, and release of a particle. The method has been successfully applied to the manipulation of both biomolecules [3] attached to a magnetic carrier and of cells decorated with magnetic particles [4]. As an example, in figure 1 we show two frames from a video taken during the manipulation of a yeast cell via displacement of a DW between two adjacent corners in a square ring.

 R. Bertacco (1), D. Petti (1), M. Cantoni (1), A. Torti (1), E. Albisetti (1), M. Donolato (2), P. Vavassori (2) (1) LNESS and CNISM, Dipartimento di Fisica Politecnico di Milano, via Anzani 42,22100 Como (Italy)  (2) CIC nanoGUNE Consolider, Tolosa Hiribidea 76, San Sebastian, 20009, Spain