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.

  • [Show abstract] [Hide abstract]
    ABSTRACT: Rapid and efficient cell purification remains challenging. The use of ferromagnetic Ni nanowires for cell purification is considered superior over magnetic beads. In this study, we explored the opportunity to improve cell purification by using antibody-functionalized Ni nanowires. Antibody (anti-CD31) against mouse endothelial cells (MS-1) was conjugated to Ni nanowire surface by self-assembled monolayers (SAMs) and chemical covalent reaction. The antibody functionalized nanowires were used to purify the MS-1 from a mixture of MS-1 and mouse fibroblast cells (3T3). The nanowire-bound cells were magnetically separated to determine the separation yield of target cells. Furthermore, the proliferation of nanowire-bound cells was studied by MTT cell proliferation assay. This work demonstrates that antibody-functionalized Ni nanowires provide an effective mean to separate cells.
    SPIE Defense, Security, and Sensing; 05/2009
  • [Show abstract] [Hide abstract]
    ABSTRACT: Cobalt nanowires, 40 nm in diameter and several micrometers long, have been grown by controlled electrodeposition into ordered anodic alumina templates. The hcp crystal symmetry is tuned by a suitable choice of the electrolyte pH (between 3.5 and 6.0) during growth. Systematic high resolution transmission electron microscopy imaging and analysis of the electron diffraction patterns reveals a dependence of crystal orientation from electrolyte pH. The tailored modification of the crystalline signature results in the reorientation of the magnetocrystalline anisotropy and increasing experimental coercivity and squareness with decreasing polar angle of the 'c' growth axis. Micromagnetic modeling of the demagnetization process and its angular dependence is in agreement with the experiment and allows us to establish the change in the character of the magnetization reversal: from quasi-curling to vortex domain wall propagation modes when the crystal 'c' axis tilts more than 75° in respect to the nanowire axis.
    Nanotechnology 11/2014; 25(47):475702. DOI:10.1088/0957-4484/25/47/475702 · 3.67 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: The latest advances in mesocrystal formation and non-classical crystallization of pre-synthesised nanoparticles have been reviewed with the focus on providing a fuller description of a number of complex systems and their properties and applications through examination of the crystallisation mechanisms at work. Two main crystallization principles have been identified; classical crystallization and particle based aggregation modes of non-classical pathways. To understand the non-classical pathways classical crystallization and its basics are introduced before non-classical pathways, such as oriented attachment and mesocrystal formation, are examined. In particular, the various destabilization mechanisms as applied to the pre-synthesized building blocks in order to form mesocrystaline materials as well as the interparticular influences providing the driving forces are analyzed and compared to the mechanisms at work within classical crystallization. Furthermore, the new properties of the mesocrystalline materials that derive from the collective properties of the nanoparticular building units, and their applications potential are presented. It is shown that this new class of materials has the potential to impact in a number of important areas such as sensor applications, energy conversion, photonic crystals as well as for energy storage, optoelectronics and heterogeneous catalysis or photocatalysis.
    CrystEngComm 09/2014; 16(40). DOI:10.1039/C4CE00882K · 3.86 Impact Factor


Available from