Biomedical Engineering Reference
In-Depth Information
Figure 3.5 Magnetofection technique in cell culture.
superficial areas, but to deliver DNA to particular organs, surgery is required. To over-
come this problem and to enhance the introduction of gene vectors into cells [254] ,
the new means of physical gene delivery is magnetofection, which delivers DNA to
the target organ, using the magnetic field. Magnetofection basically involves attach-
ing DNA onto a magnetic nanoparticle coated with a cationic polymer like polyeth-
ylenimine (PEI) [254,255] . The magnetic nanoparticles are generally made up of a
biodegradable substance like iron oxide, and its coating onto the polymeric particle
is done by salt-induced colloidal aggregation. These prepared nanoparticles are then
localized in the target organ by the application of an external magnetic field, which
allows the delivery of attached DNA to the target organ, as shown in Figure 3.5 .
This method also increases the uptake of DNA into target cells as the contact time
between the target organ and magnetic nanoparticles increases. In addition, the mag-
netic field pulls the magnetic nanoparticles into the target cells, which also helps to
increase the uptake of DNA [256,257] . In addition, the standard transfection using
viral or nonviral vectors is also increased by the magnetofection.
The magnetofection has some drawbacks: a particle size below 50 nm renders
it not suitable for magnetic targeting and too large a particle size (more than 5 m)
retards the entry of magnetic nanoparticles inside the blood capillaries. The blood
flow rate also affects the transfection efficacy of this method; for example, the flow
rate of around 20 cm/s in the human aorta makes the transfection tricky. The external
magnetic flux density and gradient decreases at a distance from the magnetic pole,
which also affects the transfection efficacy.
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