Polymeric encapsulation
The problem with current drug formulations is that they aren't always soluble, and cannot be taken up by our bodies efficiently. Drugs have to pass over membranes and also be transported in the blood stream. Packing drugs into polymeric "packets" make them easier to absorb by the body. The polymers are hydrophilic on one side (water-loving) and hydrophobic on the other (orient themselves away from water) (see below). When the polymers are mixed with the drug particles, they organise themselves around the drug molecules so that the hydrophobic ends surround the drug on the inside, while the hydrophilic ends form the outside shell. This makes the molecule soluble and easier to transport in the blood stream.
These nanomolecules are often adapted with proteins or peptides on the surface in order to target them to the specific area in the body where the drug is supposed to take effect. One way that this is done is by adding antibodies to the shell of the nanomolecule (see below). These antibodies recognise receptors that are expressed specifially on the surface of tumors. This means that, once the nanomolecules have reached the tumor, they bind to the receptors and are taken into the tumor cells by a mechanism called endocytosis. In this way the often highly toxic cancer drugs do not affect other, healthy tissues in the body.
Magnetic nanoparticles
Metal-based nanoparticles can be used to target tumors without affecting other tissues, and without exposing the patient to harmful chemicals used to treat cancer. Magnetic nanoparticles are injected directly into the tumor (such as a brain tumor). The patient is then placed in a magnetic field that makes the magnetic poles of the nanoparticles alternate rapidly, causing an increase in heat. The increased heat causes the nanoparticles to be absorbed into the cancer cells. The magnetic field treatment is repeated, causing a further increase in heat. The particles also oscillate, which destroys the cells. The destroyed cells are excreted by the body. The 1-hour treatment is repeated 6 times, but the nanoparticles are only injected once, which makes this a good alternative to conventional chemotherapy.
