Switchable Cell Trapping Using Superparamagnetic Beads

Abstract

Abstract-Ni81Fe19 microwires are investigated as the basis of a switchable template for positioning magnetically-labeled neural Schwann cells. Magnetic transmission X-ray microscopy and micromagnetic modeling show that magnetic domain walls can be created or removed in zigzagged structures by an applied magnetic field. Schwann cells containing superparamagnetic beads are trapped by the field emanating from the domain walls. The design allows Schwann cells to be organized on a surface to form a connected network and then released from the surface if required. As aligned Schwann cells can guide nerve regeneration, this technique is of value for developing glial-neuronal co-culture models in the future treatment of peripheral nerve injuries.

Integrated capture, transport, and magneto-mechanical resonant sensing of superparamagnetic microbeads using magnetic domain walls

“…Recent work has shown that, owing to their highly localized stray fields, magnetic domain walls (DWs) in magnetic nanotracks can be used to shuttle individual SPM microbeads and magnetically tagged entities across the surface of a substrate. [17][18][19][20][21][22][23]26 By integrating a single-bead detection mechanism into such DW-based transport structures, microscale sorting and sensing of single cells or biomolecules could be simultaneously achieved in magnetic lab-on-a-chip devices. Magnetoresistive sensors, which exhibit a perturbed response to applied excitation fields due to the presence of beads at the sensor surface, [1][2][3][13][14][15][16][17] form the basis for most SPM bead sensing platforms.…”

“…However, sensitivity at the level of individual microbeads has not yet been demonstrated using such a mechanism. Domain walls in nanotracks can be used to reversibly capture and transport SPM microbeads, [17][18][19][20][21][22][23]26 and it was recently shown that DWs can also be used to sense the presence of individual beads. 13,17,26 Llandro et al 13 demonstrated the detection of individual beads by measuring the effect of their stray field on DW-mediated magnetization switching in pseudo-spin-valves.…”

The effect of trapping superparamagnetic beads on domain wall motion

“…Superparamagnetic beads are widely used within bioscience to separate, organize and manipulate biomolecules and cells, [1][2][3][4][5][6] and have promising clinical applications as they can be used as MRI contrast agents and in magnetic hyperthermia for the treatment of cancer. 7,8 Typically, they consist of iron oxide (Fe 2 O 3 or Fe 3 O 4 ) nanoparticles embedded in a polymer matrix, which may have an outer coating functionalized for a particular biological application.…”

“…This has recently been exploited by devices that manipulate beads using stray fields from localized field sources such as closure domains of patterned elements 4,10,11 or domain walls in nanowires. 5,6,12,13 If the beads are attached to cells, the use of nanostructures enables the alignment or pattering of cells, 6 providing a fundamental control over cellular organization, which could generate future tissue engineering applications. In addition, domain walls may be propagated using applied magnetic fields or spin-polarized currents, so biological material attached to the beads can be translated over a pre-defined path.…”

Microfluidics cell sample preparation for analysis: Advances in efficient cell enrichment and precise single cell capture

“…Recently, the use of domain walls (DWs) in magnetic conduits patterned on a chip has been proven viable to achieve highly controllable motion of single micro and nanoparticles. 125 DWs in magnetic nanostructures provide localized sources of a strong magnetic field gradient used to trap and externally manipulate individual cells. 126 (Fig.…”