Page 165 - Bio Engineering Approaches to Cancer Diagnosis and Treatment

7.4 Electromagnetic fields application in drug delivery 163

7.4.1 Magnetic nanocarriers for controlled drug delivery
Chemotherapy using special drugs is one of the most famous methods for treating
cancer. The main task of the special drugs is to eliminate the cancer cells without
damaging adjacent tissues. The goal of chemotherapy is to inject a high concentra-
tion of drug into the body. The cancer cells are more susceptible to chemotherapy
drugs due to their much faster growth than the healthy cells [17].
Scientists are still studying the unique properties of cancer cells in order to increase
the accuracy of targeting. During the chemotherapy process, in addition to cancer
cells, other cells such as hair cells and intestinal cells, which have a high growth rate,
are also attacked and their growth stops. This disrupts the patient’s affairs. The most
important weakness of the chemotherapy is that it is relatively nonselective toward
healthy and unhealthy tissue [2]. The side effects associated with chemotherapy are
the decrease in production of the blood cells, including immune system cells, painful
inflammation, and ulceration of mucous membranes of the digestive system, loss of
body hair, and dry skin. One way to reduce the amount of drug release in healthy tis-
sues is to control the delivery of the drug. The controlled delivery enables the release
of drug to the targeted tissue and avoid the spread of them throughout the patient’s
body. It also reduces the use of the required drug [2].
The macromolecular drug carriers are one of the best ways to deliver the drug
because they target only the tumors and make no poisoning to the healthy tissues.
One difficulty is to insert them into the cancerous tumors. The macromolecular drug
carrier does not easily penetrate deep enough into the tumor and tend to integrate
near the surface of the veins due to the high internal pressure of the tumor and their
small penetration coefficient [18,19]. Bayern et al. provided a comparison between
the results of conventional treatment and treatment in a controlled drug delivery.
They showed a much more effective drug delivery in a controlled manner [20].
A method of controlling drug delivery is the use of magnetic nanocarriers along
with a magnetic or an electromagnetic field. The nanocarriers is guided to the desired
place by the magnetic/electromagnetic field. In this method, the drug and magnetic
nanocarriers, which are usually made of iron, nickel, cobalt or their oxides, are
injected into the upstream of the flow of the designated tissue [5]. The nanocarriers
move along the bloodstream close to the magnetic field. Then they are accumulated
near the designated tissue wall due to the inserted force by the electromagnetic field
[5]. Then the drug is transmitted through the wall into the tissue. The schematic of
the controlled drug delivery by magnetic field is shown in Fig. 7.4.

7.4.2 Magnetic field for controlled drug delivery
In drug delivery, the magnetic field must impose high power gradient to the tar-
geted tissue. The magnetic field required is created by permanent or electrical
magnet. The magnets that are placed outside the body adjacent to the target tis-
sue collect the MNPs in the targeted area. The magnetic field gradient sharply
decreases as it moves away from the targeted tissue and therefore it does not