In Tak Jeon

Magnetically driven spinning nanowires as effective materials for eradicating living cells

We present a method to inflame cells, in vitro, by applying an alternating current (ac) magnetic field to ferromagnetic nanowires (NWs) internalized by living cells. Nickel (Ni) NWs were internalized by human embryonic kidney cells (HEK-293). The application of ac magnetic field to the cells induced spinning of the cells via the motion of internalized NWs. This resulted in cell death by physically causing damage. A study of the response of cytokine to cells with spinning NWs shows increased interleukin-6 effects when compared with responses from non-spinning cells. The spinning effect of cells caused by the application of magnetic field can be used to target and inflame the cells. Such experiments suggest the possibility of inflaming cells for the treatment of cancer.

Radio frequency-mediated local thermotherapy for destruction of pancreatic tumors using Ni–Au core–shell nanowires

We present a novel method of radio frequency (RF)-mediated thermotherapy in tumors by remotely heating nickel (Ni)-gold (Au) core-shell nanowires (CSNWs). Ectopic pancreatic tumors were developed in nude mice to evaluate the thermotherapeutic effects on tumor progression. Tumor ablation was produced by RF-mediated thermotherapy via activation of the paramagnetic properties of the Ni-Au CSNWs. Histopathology demonstrated that heat generated by RF irradiation caused significant cellular death with pyknotic nuclei and nuclear fragmentation dispersed throughout the tumors. These preliminary results suggest that thermotherapy ablation induced via RF activation of nanowires provides a potential alternative therapy for cancer treatment.

Ultrahigh Tensile Strength Nanowires with a Ni/Ni-Au Multilayer Nanocrystalline Structure

Superior mechanical properties of nanolayered structures have attracted great interest recently. However, previously fabricated multilayer metallic nanostructures have high strength under compressive load but never reached such high strength under tensile loads. Here, we report that our microalloying-based electrodeposition method creates a strong and stable Ni/Ni-Au multilayer nanocrystalline structure by incorporating Au atoms that makes nickel nanowires (NWs) strongest ever under tensile loads even with diameters exceeding 200 nm. When the layer thickness is reduced to 10 nm, the tensile strength reaches the unprecedentedly high 7.4 GPa, approximately 10 times that of metal NWs with similar diameters, and exceeding that of most metal nanostructures previously reported at any scale.

Compositional Dependence of Magnetic Properties in CoFe/Au Nanobarcodes

Nanobarcodes consisting of multicomponents and multisegments have gained attention lately because they can offer multiple functionalities. Here, we report the structure, composition, and magnetic properties of CoFe/Au nanobarcodes fabricated by a pulsed electrodeposition method in one solution bath. The nanobarcodes with three different compositions in magnetic segments including Co68Fe32 (Co-rich), Co50Fe50 (equiatomic), and Co35Fe65 (Fe-rich) exhibit different magnetic characteristics as a result of compositional variation. The highest saturation magnetization value of 1739 emu/cm3 was observed in the Fe-rich case.

Magnetic NiFe/Au barcode nanowires with self-powered motion

NiFe/Au barcode nanowires were synthesized by pulsed electrodeposition using anodic aluminum oxide nanotemplate, comprising magnetic, catalytic, and optical segments, respectively. The self-powered motion of the BNWs due to the catalytic reaction was observed in aqueous H2O2. The approach demonstrates how sophistication in barcode nanoarchitecture can be used to synthesize a wide range of hybrid materials.

Dimensional Dependence of Magnetic Properties in Arrays of CoFe/Au Barcode Nanowire

We report the synthesis method and dimension-dependent magnetic properties of CoFe/Au barcode nanowire arrays. Well-separated multisegment nanowire arrays are synthesized by a pulsed electrodeposition process in a single bath. Samples with four different aspect ratios defined as the CoFe thicknesses to the nanowire diameter are prepared to investigate dimensional effects on the magnetic properties. It is evident except for very low aspect ratio case that each hysteresis loop shows a soft magnetic characteristic with an easy axis parallel to the nanowire axis. Magnetic reversal in most samples is primarily dominated by a transverse domain wall mode.

Synthesis and magnetic properties of multifunctional CoPtAu nanoparticles

We present the synthesis and magnetic properties of multifunctional CoPtAu alloy nanoparticles of three compositions, Co0.33Pt0.33Au0.33, Co0.2Pt0.2Au0.6, and Co0.4Pt0.4Au0.2, by a modified polyol process. The x-ray diffraction and transmission electron microscopy analyses confirm the formation of the alloy nanostructure comprising Au-rich and Pt-rich nanophases, with a narrow distribution of particle sizes and provides the detailed structural arrangements. The magnetic study shows the composition dependence of the magnetic properties of the nanoparticles, from superparamagnetic for both Co0.33Pt0.33Au0.33 and Co0.4Pt0.4Au0.2 to soft ferromagnetic for Co0.2Pt0.2Au0.6.

Dynamic Microcontainers as Microvacuums for Collecting Nanomaterials After Clinical Treatments

We present a feasible method to collect ferromagnetic nanomaterials(FNMs) after clinical utilization by employing ferromagnetic microcontainers (MCs). The cubic MCs with dimensions of 200 micrometers have gold-coated nickel frames and were tethered such a way that they are able to remove FNMs from cells with the use of an external magnetic field. The study has been conducted in two parts: 1) enhancement of the motion of MCs in glass-based microfluidic channels filled with viscous fluids by magnetically-driven spinning MCs, i.e., “dynamic MCs”; 2)sweeping FNMs from the cells using magnetic attractive forces between FNMs and MCs through a “microvacuum”process. Our study shows that spinning MCs can transport better than nonspinning MCs through viscous fluids. We found that approximately 70% of FNMs internalized with human embryonic cells (HEK-293) were removed from the cells by the spinning MCs. Such in-vitro experiments suggest the possibility of resolving the issue of removing FNMs used for clinical treatments from human body after treatments.