Assembly of multicellular constructs and microarrays of cells using magnetic nanowires

Department of Physics and Astronomy, Johns Hopkins University, Baltimore, Maryland, United States
Lab on a Chip (Impact Factor: 5.75). 07/2005; 5(6):598-605. DOI: 10.1039/b500243e
Source: PubMed

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.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A previously developed cell labelling methodology has been evaluated to assess its potential to precisely control the degree of magnetic labelling. The two-step method provides a quick way of labelling cells by first biotinylating the cell membrane proteins and then binding streptavidin paramagnetic particles onto the biotinylated proteins. Characterisation studies on biotinylated HeLa cells have revealed that the biotin concentration on the cell surface can be varied by changing the biotinylating reagent concentration. At the optimal concentration (750 microm), a substantial surface biotin density (approximately 10(8) biotin per cell) could be achieved within 30 min. The degree of magnetic labelling could be altered by adjusting the concentration of paramagnetic particles added to the cells and the binding of the particles onto the cell surface was not considerably affected by the biotin density on the cell surface. The magnetic moment of the labelled cells was measured and correlated well with the degree of magnetic labelling. Cell viability studies indicated that the magnetic labelling was not cytotoxic. Magnetically labelled cells were then successfully targeted and manipulated by magnetic fields to form three dimensional multicellular structures.
    Biomaterials 09/2009; 30(33):6548-55. DOI:10.1016/j.biomaterials.2009.08.023 · 8.31 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Principle, analysis, and experimental results of a novel onchip magnetic device are presented in this paper. It provides precise contactless trapping and arraying of diamagnetic microbeads without the supply of any external energy for contamination-free biochemical applications. The trapping force modeling and computation are presented and discussed. The results demonstrate accurate modeling of the device and successful experimental achievement of precise contactless trapping of diamagnetic microbeads within a buffered paramagnetic medium
    IEEE Transactions on Magnetics 05/2007; DOI:10.1109/TMAG.2006.892269 · 1.21 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Engineering functional tissues and organs in vitro is considered integral to regenerative medicine. Many recent cell patterning technique developments position cells at a pre-designated pattern to improve tissue engineering efficiency and quality and to facilitate 3-D cell-cell interaction exploration. Among these techniques, dielectrophoresis (DEP)-based cell patterning advantageously offers speed, ease of operation, low degree of cell damage, and precision. This article reviews recent advances in DEP-based patterning techniques, including electrode design, suitable buffer and hydrogel, effects of the electric current to cells, combination potential with other techniques, as well as efforts to generate 3-D tissues.
    Biotechnology Journal 09/2006; 1(9):949-57. DOI:10.1002/biot.200600112 · 3.71 Impact Factor


Available from