No 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.

DNA nanotechnology has enabled complex nanodevices, but the ability to directly manipulate systems with fast response times remains a key challenge. Current methods of actuation are relatively slow and only direct devices into one or two target configurations. Here we report an approach to control DNA origami assemblies via externally applied magnetic fields using a low-cost platform that enables actuation into many distinct configurations with sub-second response times. The nanodevices in these assemblies are manipulated via mechanically stiff micron-scale lever arms, which rigidly couple movement of a micron size magnetic bead to reconfiguration of the nanodevice while also enabling direct visualization of the conformation. We demonstrate control of three assemblies—a rod, rotor, and hinge—at frequencies up to several Hz and the ability to actuate into many conformations. This level of spatiotemporal control over DNA devices can serve as a foundation for real-time manipulation of molecular and atomic systems.

We present a multiplex method, based on microscopic programmable magnetic traps in zigzag wires patterned on a platform, to simultaneously apply directed forces on multiple fluid-borne cells or biologically inert magnetic micro-/nano-particles. The gentle tunable forces do not produce damage and retain cell viability. The technique is demonstrated with T-lymphocyte cells remotely manipulated (a la joystick) along desired trajectories on a silicon surface with average speeds up to 20 μm/s.

We report a novel, high throughput magnetic-tweezers based 3D microchannel electroporation system capable of transfecting 40,000 cells/cm2 on a single-chip for gene therapy, regenerative medicine and intracellular detection of target mRNA for screening cellular heterogeneity. A single cell or an ordered array of individual cells are remotely guided by programmable magnetic fields to poration sites with high (> 90%) cell alignment efficiency to enable various transfection reagents to be delivered simultaneously into the cells. The present technique, in contrast to the conventional vacuum based approach, is significantly gentler on the cellular membrane yielding > 90% cell viability and, moreover, allows transfected cells to be transported for further analysis. Illustrating the versatility of the system, the GATA2 molecular beacon was delivered into leukemia cells to detect the regulation level of the GATA2 gene that is associated with the initiation of leukemia. The uniform delivery and a sharp contrast of fluorescence intensity between GATA2 positive and negative cells demonstrate key aspects of the platform for gene transfer, screening and detection of targeted intracellular markers in living cells.