Autoassemblage de colloïdes magnétiques sur un réseau de plots en nickel: Application a l'électrophorèse de longs ADN

When placed in a Hele-Shaw cell and submitted to a uniform magnetic field, a suspension of superparamagnetic particles self-organizes into a 2D array of columns with hexagonal order on short distances and glasslike order on long distances. Such arrays were usefully used for fast electrophoretic separation of long DNA molecules. Although self-assembled matrices have the advantages of simplicity and tunability, it is impossible to have the precisely controlled order and pore size obtainable in a microlithographic array. We address the latter challenge here. A magnetic nickel template is prepared on one cell surface by lift-off Under a uniform external field, the nickel dots create local magnetic field gradients that attracts the beads, imposing a predefined order. We demonstrate the ability to separate long DNA molecules with these matrices and achieve the first steps of studying the resolution of the DNA separation over a wide range of posts density.