Nanotechnology in the Fight Against Cancer

The use of tiny machines to treat medical problems has been the topic of science fiction novels for as long as machines have been in existence. However, these miniscule machines aren't just the figment of an overactive imagination. For years now, scientists and engineers have teamed up to create molecule-sized machines for which there are varying purposes, depending on construction, of course. One particular area of nanotechnology currently showing a great deal of promise resides in the area of biology and medicine. Better still, is the promise it is showing in the area of cancer treatment. Perhaps nanotechnology is the path to a cancer cure, an end to one of the deadliest and most devastating diseases to plague the world today.

What is Nanotechnology?

Before one can fully understand the benefits of nanotechnology, one must understand what exactly nanotechnology is, and isn't. According to the National Nanotechnology Initiative (N.d) "Nanotechnology is the way discoveries made at the nanoscale are put to work." Using our topic of study, this means creating materials of nanoscale to fight cancerous cells within the body. These nano-creations must be small enough to fit inside the body, and smaller still in order to fit inside a human cell. As such, nanotechnology constructs and employs materials and devices that fit within nanoscale dimensions, which as Lexi Krock from PBS's NOVA Science Now program (2005) states "a nanometer is 1/80, 000^th the width of human hair." Using this sort of scale, it is easier to understand just how small nanotechnology is, and thus why it is so important in medicine and biology today.

Why Cancer?

Cancer is one of the most prevalent and hard to treat diseases in the world today due to the way in which it affects and infects the body. Cancer is derived from a mutated cell in the body, which then multiplies, forming a mass of similarly mutated cells. As these cells grow and multiply, they form what is commonly referred to as a malignant tumor. From this primary tumor chucks or single cells break away and gain access to other systems, thus spreading throughout of the body. This metastasis is what makes cancer so difficult to treat. Secondary tumors may form as a result of these breakaways, thus making the cancer more serious, and even harder to overcome.

Keeping this in mind, scientists and medical professionals have turned to nanodevices for aid in overcoming this devastating illness. It is hoped that these devices can achieve what other forms of medicine have failed to do. While such treatments as chemotherapy work to kill cancer cells, they also kill healthy body cells, thus rendering the body weak. Other side effects of the radiation include pain, nausea, and hair loss, which greatly affect the patient's quality of life.

Applying Nanotechnology to the Battle Against Cancer

Since nanotechnology was aimed at conquering cancer, a great deal of progress has been made. Not only have scientists formulated theories as to how different nano-creations would fight in the body against cancerous cells, they've actually created a number of them. Nanotubes, nanowire, nanocantilevers, nanoshells, nanoparticles, liposomes, fullerenes, and dendrimer, are all inventions that nanotechnology engineers are working on and researching in hopes of using them in the future to treat cancer (NOVA, 2005). Each of the aforementioned also make up the two areas in which nanotechnology is being applied to cancer. These two areas are cancer treatment, and cancer detection.

Detecting any illness early is one of the best and most promising methods of fighting disease, and cancer is no different. Early detection of cancer allows physicians to target cancerous cells and/or masses before they are able to spread into other parts of the body, thus making the survivor rate significantly higher. In contrast, the survivor rate for those with late detection cancer is much lower. With this in mind, scientists are working on diagnostic nanotechnology by which to detect cancerous cells within the body at an earlier rate, and much more accurately, than current detection methods. According to the National Cancer Institute (N.d), "Nanodevices can provide rapid and sensitive detection of cancer-related molecules by enabling scientists to detect molecular changes even when they occur only in a small percentage of cells."

Nanowires are just one of the nanodevices currently being researched for cancer detection possibilities. Although nanowire is five times smaller than a strand of human hair, it is also stronger than spider silk (NOVA, 2005)! This hefty little "wire" is constructed of carbon, silicon, and various other materials that monitor biological phenomenon and report the information back to medical care providers that monitor the nanowire (National Cancer Institute, N.d). A 2002 Harvard research team reported that their constructed nanowires were capable of detecting low levels of protein, more specifically PSA (prostrate-specific antigen), which is four times smaller than the levels that are able to be detected in the blood (Harvard University Gazette, 2002). This means that prostrate cancer can be detected sooner, thus increasing possible treatment options, and possibly even the survival rate of prostrate cancer patients. While the Harvard study did not look into other types of cancers, Professor Lieber did assert his belief that the concept used in prostrate cancer detection would also be able to be used in breast and ovarian cancers, as well as various other diseases (Harvard University Gazette, 2002).

Another promising piece of cancer detecting nanotechnology is the nanocantilever, a beam anchored on one end, and engineered to bind to molecules associated with cancer. Cancer associated molecules may be mutated DNA sequences or proteins that vary depending on cancer type; however, as these molecules bind to the nanocantilever, the cantilever bends, thus creating a situation in which professionals can monitor thecantilever and observe the bend, indicating that a cancerous molecule is present (National Institutes of Health, 2001).

While early detection is extremely helpful, researchers are also looking into nanodevices to treat cancer. A 2005 Stanford University study revealed huge success in the field of nanotechnology. Published by the Proceedings of the National Academy of Sciences, the study unveiled the use of nanotubes to kill cancerous cells in the body. Early research into carbon nanotubes found that, when passed under a near-infra red laser beam the solution containing the nanotubes heated up to a stunning 70C within a two minute time period (BBC News, 2005). This discovery spurned the idea of placing the nanotubes inside actual cancerous cells, with the idea that the heat generated by the combination of the nanotubes and the near-infra red laser beam would destroy the cell. In order to do this, the team coated the nanotubes with folate molecules, a vitamin draw into cancerous cells through receptors blanketing their surface. Thus, the folate coated nanotubes were taken in by cancerous cells, but left alone by the healthy cells without folate receptors. After being exposed to the aforementioned laser beam, the result was both clear and encouraging. The cancerous cells were killed off, while the healthy cells remained in tact. Although this breakthrough is but an early step, it displays great promise in the search for cancer treatment. It has opened up a new avenue of research, and given scientists an area in which to refine for possible future use in human cancer cells, as opposed to the Petri dish cells which have thus far been tested on.

Nanoshells are another innovation of nanotechnology focused at treating cancerous cells. Nanoshells are hollow spheres covered with gold that are able to absorb near-infrared light. Similar to the previous nanodevice, the nanotubes, this heat is capable of killing cancer cells. However, this isn't the principle that is most sought after by researchers. Instead, researchers are linking nanoshells to antibodies capable of recognizing cancer cells so that these nanoshells seek out cancerous targets. Once the cancerous targets have been reached, scientists can apply the infrared light, and thus kill the cancerous cells (National Institute of Health, 2001). Furthermore, PBS's NOVA (2005) notes that the heat generated by the nanoshells can be controlled through the thickness of the gold that coats it, in conjunction with the size of the laser used during the "destruction" phase.

The pluses of the nanoshell don's stop there. In addition to having the ability to target and destroy cancer cells, nanoshells are being predicted to one day be used as drug releasing agents. As the shells are heated, they would release a controlled amount of a chosen drug. This use is another area in which cancer treatment has gone in recent years. According to Arruebo, et al (2007) the benefits of nano based drug delivery systems is their "...ability to target specific locations in the body; the reduction of the quantity of drug needed to attain a particular concentration in the vicinity of the target; and the reduction of the concentration of the drug at non-target sites," thus minimizing severe side effects (22 - 32). Nanoshells aren't the first nanodevice to be looked into for this purpose. In fact, Liposomes, a nanodevice mentioned earlier in this paper, was the first nanodevice to be used for drug delivery. Liposomes served to eliminate such cancer drug side-effects as hair loss and nausea. However, eliminating side effects isn't the only aim of drug-delivering nanodevices. Like chemotherapy, cancer treatment dugs can affect healthy cells along with the cancerous one. Liposomes were also created as a means of delivering effective drugs, but in a manner which protects healthy cells. NOVA (2005) notes that "During cancer treatment they (liposomes) encapsulate drugs, shielding healthy cells from their toxicity, and prevent their concentration in vulnerable tissues such as those of a patient's kidney and liver." It is this goal that current nanodevices are created to meet, as well as the former goal of drug delivery.

Fullerene, a nanodevice first looked into in the mid 1980s, has far greater implications than the early liposome; as does its counterpart the dendrimer. The first of these, the fullerene, is a particle of crystalline construction, arranged in a soccer ball like fashion (NOVA, 2005). These odd crystalline molecules are unique in drug delivery because they don't dissolve or break apart in the body. Instead, these nanodevices excrete their medication, which helps to preserve healthy cells from harm. NOVA (2005) describes an interesting use of fullerenes, explaining that filling the particles with radioactive atoms "would allow for the complete removal of radiation from the body following treatment."

The second of these dendrimers, are highly complex branched polymers that were developed as another means of drug delivery. However, they also double as an imagining agent. Dendrimers are the latest nanodevice to be created and the scientific and medical swell around them is great. The NCI Alliance for Nanotechnology in Cancer (2006) reports that efforts are being made to "create a 'working proof-of-principle example' of a single dendrimer containing targeting, imaging, and therapeutic functions." The amazing construction of these nanoparticles opens up a great deal of promise for it in the treatment of cancer. Since the dendrimer contains a vast number of branches which have sticky points at the end, the dendrimer is perfectly fitted for attaching a number of different agents to aid in the fight against cancer. The National Dendrimer and Nanotechnology Center (N.d) notes that "By adjusting chemical properties of the core, the shells, and especially the surface layer, dendrimers can be tailored to fit the needs of specific applications." In essence, the dendrimer can become a smart nanoparticle, fit for seeking and attacking cancerous cells, while preserving healthy ones.

In fact, the University of Michigan has succeeded in constructing a dendrimer with five specialized branches for cancer fighting; the first of these is a molecule for binding to cancer cells, the second for locating gene mutations, the third for assisting in the imaging of tumors, the fourth a release-on-demand drug delivery system, and the fifth a signal to indicate the decease of cancer cells (as a monitor of progress) (NOVA, 2005). While these amazing nanoparticles are still being researched in laboratory Petri dishes, they are set to begin experiments in animals soon. Hopefully this promising step will soon find dendrimer's as a real and highly effective method in treating cancer.

While cancer fighting nanotechnology is still in its early stages, the promises thus far shown are enough to make doctors and scientists alike anxious. At this point there are a number of different nanodevices being researched, and implemented in the fight against cancer. The devices listed above are only some of the developments that have thus far been made. The NCI National Alliance for Nanotechnology in Cancer lists numerous other beginnings and developments in nanotechnology as it pertains to the treatment of cancer. Will cancer always be as deadly and devastating a disease as it currently is? Perhaps it is too early to tell as of yet, but if there is a cure to be found it seems that nanotechnology is the avenue by which to seek it.

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