Engineered Nanomaterials for Medical Applications
Daniel S. Choi
Dr. Choi's research group:
http://www.webpages.uidaho.edu/~dchoi/GROUP_~1.HTM
My research group is dedicated to develop and produce nanowires of virtually any materials, ranging from metals and semiconductors to conductive polymers for device applications. In particular, two kinds of nanowires such as “nanowires suspended in variety of solvents and integrated nanowires grown on substrates” can be produced. Since growth of our nanowires is a template-based process, nanowire dimensions (diameter and length) can be precisely controlled.
Nanowire dimensions
Nanowire dimensions are made to the desired specifications within the following range:
· Diameter: 15 nm – 200 nm
· Length: 1 mm – 20mm
Nanowire materials
Available nanowire materials are as followings:
· Single component ® Au, Ni, Cu,
Ag, Pt, Sn, Pd, Co, CdTe, Fe-oxide, Zn-oxide, conductive
polymer, more
· Multi-layered ® Fe/Ni, Au/Fe/,
Au/Ni, Ni/Au/Ni, Co/Cu, more
Figure 1: Schematic illustration of fabricating nanowires suspended in a solution.
In addition, we’ve been developing a process of growing nanowires in the particular location of interest, so called “growth of addressable nanowires”. The SEM images below are showing Pt nanowires grown on the “Y” line (a), and a vertical array of nanowires grown on a SiO2/Si substrate (b).
(a) (b)
Figure 2: SEM image of a vertical array of Pt nanowires grown on the “Y” (addressable nanowires) (a), and a vertical/ordered array of nanowires grown on a SiO2/Si substrate
Prior work (Choi’s group) related to this proposed research “Embryonic effects of nanomaterials” is summarized as below:
- “Magnetic nanowire stimulation of inflammatory pathways in dissociated neuron cultures”
Neuron interaction with biochemical and patterned topographical cues is explored with rat CNS neurons. Suspended carbon nanotubes and Ni nanowires are functionalized with fluophores and biomolecules. Nanofabrication modalities enable revolutionary designs of precise biomolecule-functionalized arrays for single neuron manipulation and interaction, which can lead to construction of on-demand neural networks.
Figure 3: SEM image of neurons internalized by carbon nanotubes/Ni nanowires (a), and time-resolved fluorescent images of neurons with Ni nanowires.
- “Transport of living cells with magnetically assembled nanowires”
We’re developing a technique of transporting and positioning living cells internalized by Ni nanowires guided by magnetic field. Nanoscale magnetic nanowires are internalized by the Rat Neuroblastoma and the cells are transported and positioned by magnetic fields from the magnetic material existed electrodes. This technique may enable interfacing between neurons and electronic devices to empower investigations pertaining to non-invasive neuron probing as well as nanofabricated neural pharmacological technologies.
Figure 4: Images of neurons internalized by Ni nanowires (a), and schematic illustration of transport of living cells internalized by Ni nanowires using the magnetic positioning.
- “Hyperthermia with magnetic nanowires for inactivating living cells”
We describe a method to induce hyperthermia in cells, in-vitro, by remotely heating nickel (Ni) nanowires (NWs) with radio frequency (RF) electromagnetic fields. Ni NWs were internalized by human embryonic kidney cells (HEK-293). Only cells proximal to NWs or with internalized NWs changed shape on exposure to RF fields indicative of cell death. The cell death occurs as a result of hyperthermia, since the RF field remotely heats the NWs as a result of magnetic hysteresis. This is the first demonstration of hyperthermia induced by NWs; since the NWs have anisotropic and strong magnetic moments, our experiments suggest the possibility of performing hyperthermia at lower field strengths in order to minimize damage to untargeted cells in applications such as the treatment of cancer.
Figure 5: Schematic illustration of hyperthermia process using magnetic nanowire (left), and the cell shape changed with RF inductive heating. (a) HEK-293 human kidney cells after 4 days of culture, (b) after 13 hour incubation with nanowires, (c) nanowires kept for 4 min, (d) HEK cells before RF inductive heating process, (e) nanowires attached to the cells and heated by RF inductive coupling for 2 min, (f) nanowires heated by RF inductive coupling for 4 min. Arrows indicate the dead cells floating around in (e) and (f).
