Nanotechnology in the Treatment of Cancer

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1 Page 1 of 11 Nanotechnology in the Treatment of Cancer What is Nanotechnology The term Nanotechnology originates from the Greek word meaning dwarf. The scale of nanotechnology puts into perspective how small or dwarf-like the technology is based on comparisons to the human scale. A nanometer (nm) is one-billionth of a meter, a micrometer a millionth of a meter. Nanotechnology refers to a world of atoms and nanostructures so small that cannot be seen unless using a specialized microscope. An atom has the diameter of 0.1nm, the diameter of a single human hair is hundred-thousandth of a nanometer, or micrometers, red blood cells are 6 micrometers and DNA molecules are nanometers. What is nanotechnology? (n.d.). Nanotechnology in nanomedicine is a complex subject that refers to the technology that is smaller than 100 to 200 nanometers. The goal of nanotechnology is to manipulate and control individual atoms from the building blocks of the universe such as carbon, hydrogen, oxygen, on the atomic or molecular scale to build microscopic devices (robots that will fight disease such as cancer. (Bonsor, Kevin, and Jonathan Strickland 25 October 2007.) Nanotechnology is based on the process of building things from the bottom-up with atomic precision. Traditionally, we build things from top-down meaning if we need to build a table we cut the tree then we go through the manufacturing process of building the table. Nature on the other hand builds things from the bottom up or self-assembly. Atoms join together to make molecules. Each molecule has a certain structure and when molecules come

2 Page 2 of 11 together they make cells to become a tree. (Nanotechnology Press Kit - History of Nanotechnology. 2008, Mar. 29). (Nanotechnology 2008). Today, scientists, engineers take control of atoms and molecules manipulate them and use them with great precision. Nanotechnology manipulates each atom to create a tiny structure or nanomachine copying nature. Nanotechnology is important because at the nanoscale properties of molecules change, and some materials have increased strength, decreased weight, greater electrical connectivity, different magnetic properties, reflect light better and the ability to change shape or color on demand by manipulating the atoms. By understanding individual molecules properties nanoscientists can build new materials. Nano scientists hope to replicate nature s ability to manipulate specific atoms which eventually selfassembly will occur into elaborate structures. (Nanotechnology 2008). Historical Background In 1959, physics professor Richard Feynman gave a lecture to the American Physical Society called There s Plenty Room at the Bottom. The focus of his speech was about the field of miniaturization and how he believed man would create increasingly smaller, powerful devices. He believed that the principles of physics allow man, to manipulate atom by atom. Microscopes at that time didn t exist that allowed scientists to see atoms. I want to build a billion tiny factories, models of each other, which are manufacturing simultaneously... The principles of physics, as far as I can see, do not speak against the possibility of maneuvering things atom by atom. It is not an attempt to violate any laws; it is

3 Page 3 of 11 something, in principle, that can be done; but in practice, it has not been done because we are too big. Richard Feynman, Nobel Prize winner in physics Feynman never mentioned the term nanotechnology however he was the first to predict the future of nanotechnology and to bring forward the idea to build nano-scale machines and have them build millions of factories. (Feynman, R. 1959, December 29). In 1974 Tokyo scientist Norio Taniguchi from Tokyo University, first defined nanotechnology and his statement was: "'Nano-technology' mainly consists of the processing of separation, consolidation, and deformation of materials by one atom or one molecule." History of Nanotechnology. (1986, Jan. 1). In 1986, K. Eric Drexler, a student of Feynman wrote Engines of Creation and popularized the word nanotechnology. The following year wrote Nanosystems: Molecular Machinery, Manufacturing and Computation. The books describe the principles and mechanisms of molecular nanotechnology. The manipulation of one atom at a time and control of the atom was described. Drexler believed that scientists could create nanobots which in turn would build on their own other nanobots. The term grey goo was introduced by Drexler which describes how self- replicating nanobots will take over earth. Today many nonscientists believe that Drexler s nanobot s theory is science fiction. (History of Nanotechnology. 1986, January 1)

4 Page 4 of 11 The Science of Nanotechnology Atoms are the building blocks for all matter in our universe. Everything around us is made from atoms. The elements that occur naturally on earth are hydrogen, oxygen, carbon, silicon, iron, copper and aluminum. All materials are made from these building blocks. Nanoscience requires researchers to assemble and rearrange and control atoms, trying to make useful products. Nanomaterials The study of Nanomaterials is how materials behave when they are reduced to the nanoscale. Nanomaterials include a wide range of materials such as, nanocrystalline materials, nanocomposites, nanoparticles, carbon nanotubes, and quantum dots. The common link between these materials is that on the nanoscale they have micro structural features. In other words the nanomaterials structures or how the atoms fit together can be seen using a specialized high powered microscope which shows the different physical, chemical, electrical and magnetic properties. It s important to look at engineered nanomaterials as a whole, more than individual parts and what happens when they are put together. Objects behave differently when they have been reduced from the larger scale materials to the nanoscale. Properties of materials change as materials are reduced to the nanoscale. An example could be seen in graphite and diamond which both are made from carbon atoms but both have very different properties. At the nanoscale, the rearrangement of the carbon atoms has different properties than the human scale. Another example is when gold is reduced to the nanoscale, it is red and in liquid form.

5 Page 5 of 11 Fullerenes Fullerenes are molecules composed entirely of carbon, in the form of a hollow sphere, ellipsoid, tube or plane. Fullerenes were named after Richard Buckminster Fuller an architect known for his geodesic domes, American pavilion in Montreal Expo 67. Spherical Fullerenes look like a soccer ball. Natural carbon exists in several forms, graphite and diamond. In 1985 Robert Curl (Rice University), Harold Kroto (University of Sussex) and Richard Smalley(Rice University) discovered a third type of carbon, C 60 known today as the buckyball. These 60 carbon atoms are arranged in a spherical cage-like or soccer ball like structure and were discovered in the byproducts of laser vaporization of graphite in which carbon atoms are arranged in sheets. The van der Waals diameter of C 60 molecule is about 1 nanometer (nm). Van der Waals explains the momentarily attraction of molecules. Researchers have found spherical fullerenes known as bucky balls and cylindrical, called carbon nanotubes or buckytubes. In 1996, Curl, Kroto, and Smalley won the Nobel Prize for their discovery. (Fullerene. 2008, April 24). Carbon Nanotubes Carbon nanotubes are a hexagonal lattice (looks like chicken wire) of carbon rolled into a cylinder which was discovered by S. Iijima in Nanotubes have a range of electrical, thermal and structural properties and are approximarely 2 nanometers in length. The smaller a particle, the greater the surface area to volume ratio. (Implications of nanotechnology. 2008, April 28). Nanotubes exhibit extraordinary strength and flexibility. There are different forms of nanotubes single walled or multiple walled cylinders.carbon nanotubes can be filled and capped which could be used as a drug delivery device. (Nanotechnology Glossary. n.d.).

6 Page 6 of 11 Instrumentation and Metrology Nanotechnology manipulates matter at the atomic level or nanometer scale. In order to manipulate atoms and replicate devices nanoscientists must have instrumentation and metrology, in other words a method to measure the properties of matter. Nanoscintists required not only to view atoms and manipulate but also to be able to collect data in a meaningful way. Once nanoscientists understand the science at the atomic level nanotechnology could be developed. Scanning Probe Microscope/Atomic Force Microscope At the nanoscale objects are so small you can t see them. In 1989, November 9, at IBM s Almaden Research Center in San Jose,a group of scientists shocked the world when they spelled I-B-M using 35 Xenon atoms in total. ( I-B-M Spelled in Xenon Atoms.n.d.) The moving around atoms was the beginning of how atoms can be manipulated one at a time. The manipulation of atoms was the prediction coming true of the pioneer of nanotechnology, Richard Feynman. A Scanning Probe Microscope isn t like a regular microscope. SPM allows nan0scientists to see, by using a small needle that conducts electricity which feels the surface of the atom. This special instrument uses a fine probe that is scanned over the surface of the material. A feedback mechanism is used to maintain the tip at a constant height over the sample and signals are sent back to the computer for data collection, processing and display. (Bonsor, K., & Strickland, J. 2007, Oct. 25).Scanning Probe Microscopy refers to various techniques that

7 Page 7 of 11 use a sharp scan probe to scan and measure atoms, other examples are STM (scanning tunneling microscopy), AFM (atomic force microscopy), NSOM (Near-Field Scanning Optical Microscopy) and anew type called STEM (scanning transmission electron microscope). (Steele, B. 2008, Feb. 21) What is Nanomedicine? Nanomedicine is the construction of nanometer medical devices such as nanomachines or nanorobots. With nanotechnology atoms and molecules could be manipulated then programmed for specific biological tasks. All disease could be traced at the cellular level. Nanomedicine involves the medical use of nanomaterials, nanoelectronic biosensors, nanomedical approaches to targeting molecules and drug delivery with precision, nanodevices programmed to detect, evaluate, treat and report to a doctor. These nanomedicine devices will affect all areas of medicine but will definitely change how cancer is treated. Imaging agents will allow doctors to detect cancer in its early stages. Society will benefit because nanotechnology will allow targeting disease without the adverse side effects. (Exploring Nanotechnology in Cancer. n.d.) Cancer and Nanotechnology Cancer refers to many types of diseases that have an abnormal growth of cells in the body. Cells are the building blocks of the human body. As cells grow and divide they perform different types of jobs. Cancer is formed when cells keep dividing and destroy normal body tissue, or healthy cells.

8 Page 8 of 11 Chemotherapy is a drug approach to treat cancer. As cancerous cells divide out of control, drug administration is used to control the cancer. The problem with chemotherapy is that the drugs kill cancerous as well as healthy cells, leaving the person with side effects like loss of hair, nausea, digestive problems; lack of energy and mouth ulcers. (Exploring Nanotechnology in Cancer. n.d.) Nanotechnology currently is used on mice and was approved as of January 2008 to treat cancer on humans. The difference between nanomedicine and chemotherapy is that nanomedicine only destroys the cancer cells. To treat cancer there are several nanodevices that are being used. Different types of cancers have different proteins on their surfaces that act as markers. First nanoparticles are injected inside the body with specialized antibodies attach on the cancerous protein markers. Another device tracks the nanoparticles and acts as contrast enhancing agent when the particle has attached to the cancer cell through a blood sample, and allows doctor to see the tumor at its earliest stages. Once particle is where it needs to be, signals are sent to destroy the cancerous cell. (Silverman, J. 2007, Aug. 3) An important aspect is that drugs need to be protected as they travel through the body in order for them to be effective. Once the drug arrives at its destination it goes through a process called encapsulation and needs to be released at an appropriate time so it can be effective. (Lauterwasser, C., Anthony, M., & Stevens, B. n.d.). Nanotechnology devices are used in cancer because they are 100 to times smaller than human cells. Since the nanodevices are so small they are able to circulate around the body, interact on the surface of cells and enter cells when needed. This ability allows nanoscientists to develop diagnostic and therapeutic nanodevices. (Exploring Nanotechnology in Cancer. n.d.)

9 Page 9 of 11 Nanoshells in the Treatment of Cancer Nanoshells are nanoparticles that have optical properties. Nanoshells are an effective form of cancer therapy on mice, developed at Rice University. Nanoshells are spheres, made from a compound called silica. Silica is found in nature as sand or quartz, and is the main component of hard substances such as glass and concrete. Nanoshells are hollow silica spheres surrounded by a shell of gold. Gold is a biocompatible compound which is important when creating nanoshells or biomedical materials. (Nanoshell. 2008, March 10). The inner core of the nanoshell is made out of glass. There are two methods that nanoshells could be used in the treatment of cancer. Nanoshells can be targeted to bond to cancerous cells by having antibodies or peptides joined to the surface of the nanoshells because you know exactly where they are in the body. At Rice University, Dr. Naomi Halas and Dr. West and their research team applied infrared laser that passes through the flesh without harming it. The nanoshells act like nanolenses. The nanoshell absorbs the heat and heats up the gold. The temperature of the cancerous cells rises by ten to twenty degrees, destroying the cancerous cells, and causing them to die. The incredible aspect of nanotechnology is that gold in its original state is an excellent conductor of heat and electricity but not of light. Nano-gold particles absorb light which turns to heat killing cancerous cells. By varying the thickness of the gold shell scientists could have the nanoshell respond to different light wavelengths. Nanoshells are basically photo thermal cancer treatment that is tuned to respond to near-infrared light. Once the nanoshells have completed their task they are eliminated from the body. (Halas, N. 2005, April 1).

10 Page 10 of 11 Quantum Dots in the Treatment of Cancer A quantum dot, another form of nanotechnology is used for medical imaging in the treatment of cancer. Self assembled quantum dos are typically nm in size. A quantum dot is a semi-conductor particle with electrons having different energy levels due to its band gap. (Band gap. 2008, April 1)In other words quantum dots give off light when energized and absorb light. The semiconductor particles are made from cadmium selenide (CdSe), UV-blue, cadmium sulfide (CdS), visible spectrum, or cadmium telluride(cdte) infra-red and a polymer coating that safeguards cells from the toxicity of cadmium. Meaning, that wavelength of light absorbed or emitted could be controlled. Quantum dots with the same materials but different sizes emit different colors. The core or the quantum dot depends on what s being targeted. The advantage of quantum dots in the treatment of cancer is that researchers could attach quantum dots to antibodies which will look for and attach to a cancer. (Nanotechnology Glossary. n.d.) Future Applications of Nanomedicine in the Treatment of Cancer In the future scientists hope to have nanomachines that are able to diagnose and cure cancer within minutes. This aspect isn t a reality yet, however nanotubes are being looked at as a diagnostic tool for cancer. In a matter of minutes nanowires made from nanotubes could be placed in the body to pick up genetic information which will be sent back to diagnose whether DNA mutations exist. Doctors will be able to detect cancer at its exact location and determine which the mutated genes are. (Bonsor, K., & Strickland, J. 2007, Oct. 25) Researchers at the University of Michigan have created dendrimers which is a tree like branch polymer. Since a dendrimer has many branches many other molecules attach to its

11 Page 11 of 11 surface. All at the same time researchers will be able to send a dendrimer that has five tools. One branch will bind to the cancer, a second will light genetic mutations, a third will x-ray the tumor, a fourth will release the drug to kill cancer cells and the fifth will signal that the cancer cells are dead. (NOVA sciencenow Cancer Nanotech (non-flash) PBS. (2005, April 1). The difference between dendrimers, nanoshells, nanotubes and quantum dots is that dendrimers will perform a variety of tasks and the other nanomachines perform one aspect of the process at a time. The future success of dendrimers will impact how cancer is diagnosed and cured. Drs. Freitas and Merkle are two theorist of nanomedicine and what is the potential of molecular nanotechnology. (Freitas, R. 2008, April 28; Freitas Jr., R. n.d.) Future predictions are that scientists will have the ability to send into the body a large number of nanobots curing cancer which man has been unsuccessful for the pass years and correct genetic mutations. NanoRisks Nanotechnology is a new field of science and to understand nanorisks scientists must understand the structure of nanotechnology. Nanoparticles can enter the human body by different ways inhalation or by the skin. The inhalation of the nanoparticles could cause damage to the lungs. (Lauterwasser, C., Anthony, M., & Stevens, B. n.d.). At the Nanoscale nanoparticles could cross the blood-brain barrier which is a membrane that protects the brain and researchers are unclear of the toxicity of nanoparticles. (Bonsor, Kevin, and Jonathan Strickland, 25 October 2007)Nanoshells are biodegradable but we don t know what the long term effects are on the patient. (Metal Nanoshells, Cure or Curse? n.d.). Since nanotechnology or more precisely nanomedicine is a relatively new branch of science it is hard to talk about toxicity if we don t know exposure or drug dosage.