Assembly of multicellular constructs and microarrays of cells using magnetic nanowires

TLDR

The study presents a method to spatially organize mammalian cells using ferromagnetic nanowires and patterned micromagnet arrays. Nanowires are electrodeposited in nanoporous templates to achieve precise size and magnetic properties, and their high aspect ratio and remanent magnetization enable cell‑bound wires to be manipulated with low magnetic fields and trapped onto ellipsoidal permalloy micromagnets to form ordered patterns. The technique produced one‑ and two‑dimensional field‑tuned patterns of suspended 3T3 fibroblasts, forming self‑assembled one‑dimensional chains via dipolar interactions, and enabling control of cell positioning on arrays by adjusting micromagnet spacing, fluid flow, or external magnetic field direction.

Abstract

An approach is described for controlling the spatial organization of mammalian cells using ferromagnetic nanowires in conjunction with patterned micromagnet arrays. The nanowires are fabricated by electrodeposition in nanoporous templates, which allows for precise control of their size and magnetic properties. The high aspect ratio and large remanent magnetization of the nanowires enable suspensions of cells bound to Ni nanowires to be controlled with low magnetic fields. This was used to produce one- and two-dimensional field-tuned patterning of suspended 3T3 mouse fibroblasts. Self-assembled one-dimensional chains of cells were obtained through manipulation of the wires' dipolar interactions. Ordered patterns of individual cells in two dimensions were formed through trapping onto magnetic microarrays of ellipsoidal permalloy micromagnets. Cell chains were formed on the arrays by varying the spacing between the micromagnets or the strength of fluid flow over the arrays. The positioning of cells on the array was further controlled by varying the direction of an external magnetic field. These results demonstrate the possibility of using magnetic nanowires to organize cells.