Nanoparticles: Uses and Applications

Nanoparticles have one dimension that measures 100 nanometers or less. The properties of many conventional materials change when formed from nanoparticles. This is typically because nanoparticles have a greater surface area per weight than larger particles which causes them to be more reactive to some other molecules.

Nanoparticles are used, or being evaluated for use, in many fields. The list below introduces several of the uses under development.

Nanoparticle Applications in Medicine

Reseachers have demonstrated a nanoparticle that kills lymphoma cancer cells. They use a nanoparticle which looks like HDL cholesterol, but with a gold nanoparicle at it's core. When this nanoparticle attaches to a lymphoma cell it blocks the cancer cell from attaching to real HLD cholesterol, starving the cancer cell.

Researchers have developed two types of nanobubbles, which form around gold nanoparticles. When the a nanobubble formed around a hollow nanoparticle is heated with a laser the nanobubble can destroy cancer cells. However when a nanobubble formed around a solid nanoparticle is heated with a laser the nanobubble opens a temporary hole in a cell wall and allows drugs to be injected. The researchers are planning this method to selectively destroy certain types of cells, and modify others.

Researchers have combined bee venom with nanoparticles to poke holes in the protective envelope around virus particles, which kills the virus. Currently this method is being evaluated in lab testing on the HIV virus, however researchers believe the method may be used to fight other viruses.

A method being developed to tackle autoimmune diseases uses nanoparticles to deliver antigens for a particular disease into the blood stream. The antigens reset the immune system, stopping white blood cells from attacking healthy cells. This method has been tested in the lab on mice with a disease similar to multiple sclerosis with promising results.

Researchers are investigating the use of bismuth nanoparticles to concentrate radiation used in radiation therapy to treat cancer tumors. Initial results indicate that the bismuth nanoparticles would increase the radiation dose to the tumor by 90 percent.

Researchers are developing a nanoparticle intended to make very early detection of cancer tumors easier. When the nanoparticles attach to a cancer tumors the nanoparticles release "biomarkers", molecules called peptides. The idea is that since each nanoparticle carries several peptides a high concentration of these biomarkers will occur even at very early stages of cancer, allowing early detection of the disease.

A method for early detection of a disease uses nanoparticles that form clumps when they attach to proteins or other molecules that indicate the disease being tested for. The test is designed to be inexpensive and simple to perform. The solution turns blue if the nanoparticles are clumped around a protein indicating the disease; if the protein is not present the solution turns red.

Polymer nanoparticles are being developed to carry a chemotherapy drug called docetaxel directly to cancer tumors. The nanoparticles are attracted to a protein present on many types of cancer tumors, resulting in a high rate of delivery of the chemotherapy drug to the tumors. The company developing this targeted chemotherapy method is called BIND Biosciences. For more details, read the article at this link.

A method being developed to fight skin cancer uses gold nanoparticles to which RNA molecules are attached. The nanoparticles are contained in an ointment that is applied to the skin. The nanoparticles penetrate the skin and the RNA molecules attach to a cancer related gene. This method stops the gene from generating proteins that are involved in the growth of skin cancer tumors.

A method is being developed to fight aging using mesoporous nanoparticles with a coating that releases the contents of the nanoparticle when an emzyme present in aging cells is detected.

Researchers have found that aluminosilicate nanoparticles can reduce bleeding in trauma patients who have external wounds by activating the blood clotting mechanism, causing blood in a wound to clot more quickly. Z-Medica is producing a medical gauze that uses aluminosilicate nanoparticles for use on external wounds. For trauma patients with internal bleeding, another approach to reducing blood loss is required. Researchers at Chase Western Reserve University are developing polymer nanoparticles that act as synthetic platelets. Lab tests have shown that injecting these synthetic platelets significantly reduces blood loss.

Nanoparticles composed of polyethylene glycol-hydrophilic carbon clusters (PEG-HCC) have been shown to absorb free radicals at a much higher rate than the proteins in our bodies can. This method may reduce the harm that is caused by the release of free radicals after a trauma such as a brain injury

Lab studies in mice have shown that using nanoparticles to target the delivery of the clot-busting drug tPA can reduce the dosage of tPA needed; this may reduce possible side affects such as internal bleeding. The clot-busting drug is attached to a cluster of nanoparticles that break apart in regions of turbulent blood flow, such as occurs in an area where blood flow is restricted by a clot.

Iron oxide nanoparticles can be used to improve Magnetic Resonance Imaging (MRI) of cancer tumors. The nanoparticle is coated with a peptide that binds to a cancer tumor. Once the nanoparticles are attached to the tumor, the magnetic property of the iron oxide enhances the images from the MRI scan.

Nanoparticles, when activated by x-rays, generate electrons that cause the destruction of cancer cells to which they are attached. This method is intended to be used in place of radiation therapy which can cause much greater damage to healthy tissue.

Nanoparticles coated with proteins can attach to damaged portions of arteries. This method could allow delivery of drugs to damaged regions of arteries to fight cardiovascular disease.

Magnetic nanoparticles can attach to cancer cells in the blood stream. These nanoparticles may allow doctors to remove cancer cells before they can establish new tumors.

Here are several other uses of nanoparticles in the field of healthcare:

Quantum Dots (crystalline nanoparticles) that identify the location of cancer cells in the body.
Nanoparticles that deliver chemotherapy drugs directly to cancer cells.
Gold nanoparticles that allow heat from infrared lasers to be targeted on cancer tumors.
Porous silica nanoparticles used to deliver chemotherapy drugs to cancer cells.
A nanoparticle cream that releases nitric oxide gas to fight staph infections.
Nanoparticles called micelles used to carry and deliver a chemotherapy drug called paclitaxel to bladder cancer cells.

Nanoparticle Applications in Manufacturing and Materials

A synthetic skin, that may be used in prosthetics, has been demonstrated with both self healing capability and the ability to sense pressure. The material is a composite of nickel nanoparticles and a polymer. If the material is held together after a cut it seals together in about 30 minutes giving it a self healing ability. Also the electrical resistance of the material changes with pressure, giving it a sense ability like touch.

Silicate nanoparticles can be used to provide a barrier to gasses (for example oxygen), or moisture in a plastic film used for packaging. This could slow down the process of spoiling or drying out in food.

Zinc oxide nanoparticles can be dispersed in industrial coatings to protect wood, plastic, and textiles from exposure to UV rays.

Silicon dioxide crystalline nanoparticles can be used to fill gaps between carbon fibers, thereby strengthening tennis racquets.

Silver nanoparticles in fabric are used to kill bacteria, making clothing odor-resistant.

Nanoparticle Applications and the Environment

Researchers are using gold nanoparticles embedded in a porous manganese oxide as a room temperature catalyst to breakdown volatile organic pollutants in air.

Iron nanoparticles are being used to clean up carbon tetrachloride pollution in ground water.

Iron oxide nanoparticles are being used to clean arsenic from water wells.

Nanoparticle Applications in Energy and Electronics

Researchers have used nanoparticles called nanotetrapods studded with nanoparticles of carbon to develop low cost electrodes for fuel cells. This electrode may be able to replace the expensive platinum needed for fuel cell catalysts.

Combining gold nanoparticles with organic molecules creates a transistor known as a NOMFET (Nanoparticle Organic Memory Field-Effect Transistor). This transistor is unusual in that it can function in a way similar to synapses in the nervous system.

A catalyst using platinum-cobalt nanoparticles is being developed for fuel cells that produces twelve times more catalytic activity than pure platinum. In order to achieve this performance, researchers anneal nanoparticles to form them into a crystalline lattice, reducing the spacing between platinum atoms on the surface and increasing their reactivity.

Researchers have demonstrated that sunlight, concentrated on nanoparticles, can produce steam with high energy efficiency. The "solar steam device" is intended to be used in areas of developing countries without electricity for applications such as purifying water or disinfecting dental instruments.

Silicon nanoparticles coating anodes of lithium-ion batteries can increase battery power and reduce recharge time.

Semiconductor nanoparticles are being applied in a low temperature printing process that enables the manufacture of low cost solar cells.

A layer of closely spaced palladium nanoparticles is being used in a hydrogen sensor. When hydrogen is absorbed, the palladium nanoparticles swell, causing shorts between nanoparticles. These shorts lower the resistance of the palladium layer.

Nanoparticle Company Directory

Company	Products
CytImmune	Gold nanoparticles for targeted delivery of drugs to tumors
Invitrogen	Qdots for medical imaging
Evident	Quantum Dots
American Elements	Nanoparticles and Quantum Dots
Applied Nanotech	Nanoparticles, carbon nanotube composites and nanoparticle based sensors.
Antaria	Zinc oxide nanoparticles used in coatings to reduce UV exposure
Nanoledge	Epoxy resins strengthened with nanoparticles

More Nanoparticle Companies

Compiled by Earl Boysen of Hawk's Perch Technical Writing, LLC and UnderstandingNano.com. You can find him on Google+.