54 research outputs found
Switching between magnetotactic and aerotactic displacement controls to enhance the efficacy of MC-1 magneto-aerotactic bacteria as cancer-fighting nanorobots
The delivery of drug molecules to tumor hypoxic areas could yield optimal therapeutic outcomes. This suggests that effective cancer-fighting micro- or nanorobots would require more integrated functionalities than just the development of directional propelling constructs which have so far been the main general emphasis in medical micro- and nanorobotic research. Development of artificial agents that would be most effective in targeting hypoxic regions may prove to be a very challenging task considering present technological constraints. Self-propelled, sensory-based and directionally-controlled agents in the form of Magnetotactic Bacteria (MTB) of the MC-1 strain have been investigated as effective therapeutic nanorobots in cancer therapy. Following computer-based magnetotactic guidance to reach the tumor area, the microaerophilic response of drug-loaded MC-1 cells could be exploited in the tumoral interstitial fluid microenvironments. Accordingly, their swimming paths would be guided by a decreasing oxygen concentration towards the hypoxic regions. However, the implementation of such a targeting strategy calls for a method to switch from a computer-assisted magnetotactic displacement control to an autonomous aerotactic displacement control. In this way, the MC-1 cells will navigate to tumoral regions and, once there, target hypoxic areas through their microaerophilic behavior. Here we show not only how the magnitude of the magnetic field can be used for this purpose but how the findings could help determine the specifications of a future compatible interventional platform within known technological and medical constraints
Control of magnetotactic bacterium in a micro-fabricated maze
We demonstrate the closed-loop control of a magnetotactic bacterium (MTB), i.e., Magnetospirillum magnetotacticum, within a micro-fabricated maze using a magneticbased manipulation system. The effect of the channel wall on the motion of the MTB is experimentally analyzed. This analysis is done by comparing the characteristics of the transient- and steady-states of the controlled MTB inside and outside a microfabricated maze. In this analysis, the magnetic dipole moment of our MTB is characterized using a motile technique (the u-turn technique), then used in the realization of a closed-loop control system. This control system allows the MTB to reach reference positions within a micro-fabricated maze with a channel width of 10 μm, at a velocity of 8 μm/s. Further, the control system positions the MTB within a region-of-convergence of 10 μm in diameter. Due to the effect of the channel wall, we observe that the velocity and the positioning accuracy of the MTB are decreased and increased by 71% and 44%, respectively
An Electromagnetic Steering System for Magnetic Nanoparticle Drug Delivery
Targeted delivery of pharmaceutical agents to
the brain using magnetic nanoparticles (MNPs) is an
efficient technique to transport molecules to disease
locations. MNPs can cross the blood–brain barrier (BBB)
and can be concentrated at a specific location in the brain
using non-invasive electromagnetic forces. The proposed
EMA consists of two coil-core system. The cores are
added in the center of each coil to concentrate the flux in
the region of interest. The EMA can enhance the gradient
field 10 times compared to only coil system and generate
the maximum magnetic field of 160 mT and 5.6 T/m. A
12-kW direct-current power supply was used to generate
sufficient magnetic forces on the MNPs by regulating the
input currents of the coils. Effective guidance of MNPs is
demonstrated via simulations and experiments using
800-nm-diameter MNPs in a Y-shaped channel. The
developed EMA system has high potentials to increase
BBB crossing of MNPs for efficient drug targeting to
brain region
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