Simultaneous Magnetic Manipulation and Fluorescent Tracking of Multiple Individual Hybrid Nanostructures

Abstract

Controlled transport of multiple individual nanostructures is crucial for nanoassembly and nanodelivery but is challenging because of small particle size. Although atomic force microscopy and optical and magnetic tweezers can control single particles, it is extremely difficult to scale these technologies for multiple structures. Here, we demonstrate a "nano-conveyer-belt" technology that permits simultaneous transport and tracking of multiple individual nanospecies in a selected direction. The technology consists of two components: nanocontainers, which encapsulate the nanomaterials transported, and nanoconveyer arrays, which use magnetic force to manipulate individual or aggregate nanocontainers. This technology is extremely versatile. For example, nanocontainers encapsulate quantum dots or rods and superparamagnetic iron oxide nanoparticles in <100 nm nanocontainers, the smallest magnetic composites to have been simultaneously moved and optically tracked. Similarly, the nanoconveyers consist of patterned microdisks or zigzag nanowires, whose dimensions can be controlled through micropatterning. The nanoconveyer belt technology could impact multiple fields, including nanoassembly, biomechanics, nanomedicine, and nanofluidics.

Transport dynamics of superparamagnetic microbeads trapped by mobile magnetic domain walls

“…Once the bead is trapped in the potential well of the DW, the DW can be used to manipulate individual beads. Indeed, bead transport has been realized by either stepping a bead from one DW trap site to the next 19,[21][22][23][24]27 or moving it continuously with a propagating DW 20,22,25,26 . Continuous transport is limited, however, by the maximum interaction force, or binding force , between the bead and DW, which must overcome the hydrodynamic drag force on the bead as it is pulled through the host fluid 20 .…”

Angular-dependent magnetization reversal processes in artificial spin ice

“…Localised magnetic charges can be supported at the interconnections and the ability to manipulate magnetic charges in the form of magnetic domain walls (DWs) provides the basis for novel technological devices including information processing 1 and through the manipulation of bio-or chemically-functionalised magnetic nanoparticles. [2][3][4][5][6] Additionally, the patterning of 'artificial spin ice' geometries can give rise to a large number of energetically equivalent states which has been explored in both dipolar coupled systems 7,8 and interconnected networks. 9 Such structures have been suggested for macroscopic studies of fundamental frustrated phenomena and their associated emergent behavior showing strong links to the thermodynamics of the system.…”

Suppression of Walker breakdown in magnetic domain wall propagation through structural control of spin wave emission

“…This opens up a channel for energy dissipation via spin wave emission, allowing a domain wall to maintain its spin structure during propagation. Magnetic domain wall (DW) motion is significant in wide ranging applications, from spintronic technologies for data storage, 1 processing, 2 and sensing applications 3 to the manipulation of atoms 4 and nanoparticles 5 for nanoassembly or nanodelivery. Typically, DW velocity increases linearly with field 3,6 up to the Walker field, where periodic transformations of the DW spin structure results in a dramatic reduction in time-averaged DW velocity, known as Walker breakdown.…”