02-02-2013, 03:57 PM
CANCER THERAPY USING NANOTECHNOLOGY
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INTRODUCTION
Cancer is the uncontrolled growth of abnormal cells in the body. Cancerous cells are also called malignant cells. Cells are the building blocks of living things.
Cancer grows out of normal cells in the body. Normal cells multiply when the body needs them, and die when the body doesn't need them. Cancer appears to occur when the growth of cells in the body is out of control and cells divide too quickly. It can also occur when cells forget how to die. There are many causes of cancers, including:
1) Benzene and other chemicals
2) Drinking excess alcohol
3) Environmental toxins, such as certain poisonous mushrooms and a type of poison that can grow on peanut plants (aflatoxins)
4) Excessive sunlight exposure
5) Genetic problems
6) Obesity
7) Radiation
8) Viruses
However, the cause of many cancers remains unknown. The most common cause of cancer-related death is lung cancer.
Cancer is the leading cause of death worldwide. Deaths from cancer is projected to continue rising. It is estimated to have 13.1 million deaths in 2030.
Nanotechnology enables rapid and sensitive detection of cancer. It also provides therapies that aim directly and selectively at the cancerous cells. Shortcomings of the present cancer therapies such as risk damage to normal tissues and incomplete eradication of cancer are eliminated.
NANOTECHNOLOGY
Nanotechnology—science and engineering of manipulating matter at the molecular scale to create devices with novel chemical, physical and biological properties—has the potential to radically change how we diagnose and treat cancer. Although we have only recently developed the ability to manipulate technologies on this scale, there has been great progress in moving nano-based cancer therapies into the clinic and many more are in development.
MANUFACTURING NANO DEVICES
Nanoscale devices are one hundred to ten thousand times smaller than human cells. They are similar in size to large biological molecules ("bio molecules") such as enzymes and receptors. As an example, haemoglobin, the molecule that carries oxygen in red blood cells, is approximately 5 nanometres in diameter. Nanoscale devices smaller than 50 nanometres can easily enter most cells, while those smaller than 20 nanometres can move out of blood vessels as they circulate through the body.
CANTILEVERS
One nanodevice that can improve cancer detection and diagnosis is the cantilever. These tiny levers, which are anchored at one end, can be engineered to bind to molecules that represent some of the changes associated with cancer. They may bind to altered DNA sequences or proteins that are present in certain types of cancer. When these molecules bind to the cantilevers, surface tension changes, causing the cantilevers to bend. By monitoring the bending of the cantilevers, scientists can tell whether molecules are present. Scientists hope this property will prove effective when cancer-associated molecules are present--even in very low concentrations--making cantilevers a potential tool for detecting cancer in its early stages.
NANOPORES
Nanopores have cancer research and treatment applications. Engineered into particles, they are holes that are so tiny that DNA molecules can pass through them one strand at a time, allowing for highly precise and efficient DNA sequencing. As a DNA strand moves through a nanopore, scientists can monitor each "letter" on it, deciphering coded information, including mutations associated with cancer. By engineering nanopores into the surface of a drug capsule that are only slightly larger than the medicine's molecular structure, drug manufacturers can also use nanopores to control the rate of a drug's diffusion in the body.
QUANTUM DOTS
Quantum dots are miniscule semiconductor particles that can serve as signposts of certain types of cells or molecules in the body. They can do this because they emit different wavelengths of radiation depending on the type of cadmium used in their cores: cadmium sulphide for ultraviolet to blue, cadmium selenide (seen here) for most of the visible spectrum, and cadmium telluride for the far red and near-infrared. (A dot's size determines its precise colour within each range.) A polymer coating enables researchers to attach molecules such as antibodies that will seek out and attach to tumours and other targeted cells. The coating also shields nearby cells from the cadmium's toxicity. The different colours of quantum dots provide a powerful tool for labelling and monitoring multiple cells and molecules simultaneously.