Anne Hultgren
Johns Hopkins University
Network
Latest external collaboration on country level. Dive into details by clicking on the dots.
Publication
Featured researches published by Anne Hultgren.
Journal of Applied Physics | 2002
Monica Tanase; D. M. Silevitch; Anne Hultgren; Laura Bauer; Peter C. Searson; Gerald J. Meyer; Daniel H. Reich
Magnetic nanowires suspended in fluid solutions can be assembled and ordered by taking advantage of their large shape anisotropy. Magnetic manipulation and assembly techniques are demonstrated, using electrodeposited Ni nanowires, with diameter 350 nm and length 12 μm. Orienting suspended nanowires in a small magnetic field H≈10 G promotes self-assembly of continuous chains that can extend over several hundred μm. The dynamics of this process can be described quantitatively in terms of the interplay of magnetic forces and fluid drag at low Reynolds number. In addition, a new technique of magnetic trapping is described, by which a single magnetic nanowire can be captured between lithographically patterned magnetic microelectrodes. The use of three-segment Pt–Ni–Pt nanowires yields low resistance, Ohmic electrical contacts between the nanowires and the electrodes. This technique has potential for use in the fabrication and measurement of nanoscale magnetic devices.
Journal of Applied Physics | 2003
Anne Hultgren; Monica Tanase; Christopher S. Chen; Gerald J. Meyer; Daniel H. Reich
The use of magnetic nanowires is demonstrated as a method for the application of force to mammalian cells. Magnetic separations were carried out on populations of NIH-3T3 mouse fibroblast cells using ferromagnetic Ni wires 350 nm in diameter and 35 μm long. Separation purities in excess of 90% and yields of 49% are obtained. The nanowires are shown to outperform magnetic beads of comparable volume.
Journal of Applied Physics | 2003
Daniel H. Reich; Monica Tanase; Anne Hultgren; Laura Bauer; Christopher S. Chen; Gerald J. Meyer
Magnetic particles that can be bound to cells and biomolecules have become an important tool for the application of force in biology and biotechnology. Multifunctional magnetic nanowires fabricated by electrochemical deposition in nanoporous templates are a type of magnetic carrier that offers significant potential advantages over commercially available magnetic particles. Recent experimental work aimed at developing these wires for this purpose is reviewed. Results on chemical functionalization of Au and Au/Ni wires and magnetic manipulation of wires in suspension are described. Fluorescence microscopy was used to demonstrate the covalent binding of thiol-terminated porphyrins to Au nanowires, and to optimize functionalization of two-segment gold–nickel nanowires for selectivity and stability of the nanowire–molecule linkages. Magnetic trapping is a technique where single nanowires are captured from fluid suspension using lithographically patterned micromagnets. The influence of an external magnetic fiel...
Biotechnology Progress | 2008
Anne Hultgren; Monica Tanase; Edward J. Felton; Kiran Bhadriraju; Aliasger K. Salem; Christopher S. Chen; Daniel H. Reich
Ferromagnetic nanowires are shown to perform both high yield and high purity single‐step cell separations on cultures of NIH‐3T3 mouse fibroblast cells. The nanowires are made by electrochemical deposition in nanoporous templates, permitting detailed control of their chemical and physical properties. When added to fibroblast cell cultures, the nanowires are internalized by the cells via the integrin‐mediated adhesion pathway. The effectiveness of magnetic cell separations using Ni nanowires 350 nm in diameter and 5–35 micrometers long in field gradients of 40 T/m was compared to commercially available superparamagnetic beads. The percent yield of the separated populations is found to be optimized when the length of the nanowire is matched to the diameter of the cells in the culture. Magnetic cell separations performed under these conditions achieve 80% purity and 85% yield, a 4‐fold increase over the beads. This effect is shown to be robust when the diameter of the cell is changed within the same cell line using mitomycin‐C.
IEEE Transactions on Magnetics | 2004
Anne Hultgren; Monica Tanase; Christopher S. Chen; Daniel H. Reich
Ferromagnetic nanowires are demonstrated as a new tool in performing high-yield, single step cell separations on cultures of mammalian cells. The nanowires are made by electrochemical deposition in nanoporous templates, and when added to cultures of 3T3 mouse fibroblast cells, the nanowires can readily bind to the cells. The effectiveness in cell separations of Ni nanowires 350 nm in diameter and 5-35 /spl mu/m long in field gradients of 40 T/m were compared to commercially available superparamagnetic beads. The percentage yield of the separated populations is found to be optimized when the length of the nanowire is matched to the diameter of the cells in the culture. Magnetic cell separations performed under these conditions achieve 80% purity and 85% yield, a four-fold increase over the beads.
Nano Letters | 2001
Monica Tanase; Laura Bauer; Anne Hultgren; D. M. Silevitch; Li Sun; Daniel H. Reich; Peter C. Searson, ,§ and; Gerald J. Meyer
Lab on a Chip | 2005
Monica Tanase; Edward J. Felton; Darren S. Gray; Anne Hultgren; Christopher S. Chen; Daniel H. Reich
Science | 2004
Clayton Lapointe; Anne Hultgren; D. M. Silevitch; Edward J. Felton; Daniel H. Reich; Robert L. Leheny
Archive | 2003
Daniel H. Reich; Monica Tanase; Anne Hultgren; Laura Bauer; Christopher S. Chen; Gerald J. Meyer
Journal of Magnetism and Magnetic Materials | 2002
C. L. Chien; Li Sun; Monica Tanase; Laura Bauer; Anne Hultgren; D. M. Silevitch; Gerald J. Meyer; Peter C. Searson; Daniel H. Reich