Nanotechnology and Human Health

Nanotechnology at Work

Now that we have introduced topics concerning structure and properties of matter at the nanoscale we can discuss some of the ideas that are either being used currently in industry and also some of the theoretical work that is being done.

Medicine Uses: Practical and Theoretical

This section reviews ideas already in practice and theoretical research still being developed. Medical research in nanotechnology is a burgeoning field due to the major implications it could have on diseases such as cancer, cystic fibrosis, and genetic disorders. This technology is useful as it gives scientists the ability to create and generate medicines that are small enough to penetrate the cells where they are most needed (while not being detected by the body as foreign objects due to their small size) as opposed to being diluted throughout the body, or accumulating in the liver as a waste products. In order to develop these medicines, scientists must be concerned with the overall physical properties of the structure they are creating (what will it be attracted to, will it be absorbed, how well will it flow through the body). Although this section barely scratches the surface of nano applications in medicine it is enough to help understand the difficulties and benefits in working at this scale.

Medicine Creation in Nanoscale

A liposome for drug delivery is made from a lipid layer with the drug on the inside. The lipid layer is made from molecules similar to the phospholipids in the cell membrane. They are arranged with the hydrophilic head facing outwards and the hydrophobic tail facing inwards. This spherical lipid object now has a cavity into which a drug can be placed for drug delivery onto the body. The nature of the liposome prevents the drug from being diluted into the body prematurely and thus creates a stable platform for the delivery. "Liposomal drug delivery has achieved success in the past decade as Ambisome (lipid-based delivery of amphotreicin…) was approved for treatment in … meningitis and HIV infected patients". ¹⁵

Drugs can be encapsulated into polymers in a similar way. To begin with you take a container full of oil such as methyl chloride MeCl ₂ and in that you place a polymer that is oil soluble and also a medicine that is oil soluble. This solution should be mixed vigorously with the MeCl ₂ acting as the solvent for the solution. Then this gets emulsified by adding it to an agitated solution of water with a surfactant or stabilizer in it. This surfactant will be integral in the final stage of the process. As the new emulsified solution continues to be agitated the oil will quickly form very small "bubbles" in the water through properties of self assembly with bits of the polymer and medicine in it. In this state it has more surface area which helps the MeCl ₂ to evaporate out of the water. As it evaporates the polymer forms a hard shell encasing the medicine in it. Once all of the oil has evaporated the remaining substance can be filtered out it can be placed in a centrifuge and then lyophilized (freeze dried). In this state they are nanoparticles that would appear to the macroscale a very fine white powder. Under electron microscopy, the image would show many small spherical units each with medicine in it. Thanks to the surfactant that was in the solution there is now an ability to add a molecule to the surface of each of these. This molecule will also have hydrophobic and hydrophilic properties. The purpose of this is to act as a receptor site so that these nanoparticles can gain access to cells readily as they slowly dissolve in the body releasing a steady stream of medicine. This is far superior to traditional methods as the medicine is at such a small scale and can gain access to areas where it is most needed. This process is being used currently in labs and should have a promising future. For further clarification of this process see figure 4. ¹⁶

figure4

Plasmids and Viruses

A form of nanotechnology at work in research facilities, which holds future promise is the use of objects that are already occurring in nature and adapting them to our needs. The use of plasmids for the generation of insulin for diabetes patients has already been done for some time. The newest forms of this research is looking at placing the plasmid into cells for other forms of gene therapy. The process is as follows.

Plasmids are circular DNA that already naturally occurs in bacteria. The main difference is its size (it is very small compared to a full strand of human DNA) and its circular closed shape. One aspect of this plasmid that make it beneficial is the discovery of enzymes that work as a pair of scissors enabling scientists to cut a section of the DNA apart. Once this section of DNA is apart another section of DNA can be attached. This new section of DNA encodes for the production of a desired protein. The plasmid can be placed back inside a bacterium for reproduction and expression.

Viruses are fascinating objects that scientists are harvesting for use in gene therapy and research. A virus has the ability to penetrate a cells membrane due to its structure and properties. Once inside a cell, it is normally successful at implanting its DNA into the host cell, so when the host cell replicates the new viral DNA replicates with it. Now suppose, similar to the plasmids, that you replace DNA in a virus with signals to stop certain actions of a cell, or replace the DNA with a gene that correctes a certain disease. This is being researched, but one problem that scientists need to overcome is the bodies response to viral infections.

Design of Nanoscale Products for the Macroworld

The use nanoparticles is a growing phenomenon. As of July 2010 it was reported that there are three new products that come out for consumer use each week that use some form of nanoparticle. To design and utilize these particles scientists must still hurdle all of the previous physical properties of dealing with objects at this scale and then use the techniques of self assembly to make larger products.

Some of the products that are out now are fabrics that are stain resistant due to particles at the nanoscale that repel dirt and stains. It is hoped that this technology will continue growing so that one day in the future we may not need washing machines as we will be able to simply air clean our clothes (just imagine the water conservation from that). Another larger area of development is in the use of nano-silver for making water purification systems for the home and also on the industrial scale. These nanoparticles have the ability to prevent impurities from entering the water making the water that we drink much cleaner and healthier for us (chalk two up for nano in helping us with water).

Along with water purification there is also a lot of research and development into air purification systems using the same technology as the water systems.

Cosmetics and lotions are the third largest area of development in nanotechnology and also the one that is most scrutinized. Sunscreen lotions use nano zinc-oxide which has helped make sunscreen lotions that are now clear as opposed to the glaring white lotion of old. It has fantastic properties for deflecting the suns UV rays making it much better for our skin; on the downside, nano-sized particles of zinc oxide may be toxic to humans if ingested into the lungs. Cosmetics that have nano particles are falling under the same scrutiny for the same reasons. One result of this is the EPA decision in June of 2010 to rewrite their policies to include detection of nanoparticles and conduct studies for levels of toxicity for nanoparticles. The FDA is also interested in finding more information about the toxicity of certain particles before allowing them to be used for foods and drugs.

Large potential changes may occur in nanotechnology in the future. Consider the case of carbon nanotubes. Carbon nanotubes are only 2-3nm wide, but theoretically can be as long as you want. Think of a chicken wire rolled into a tube formation and this is the basic structure of a carbon nanotube. For its size and shape, these nanotubes are much stronger than steel. It is hoped that one day scientists will be able to make thousands of these at incredible lengths and twist them together like a rope or steel cable. The difference is this material will be lighter and stronger than steel. One implication of this is that humans might be able to build a suspension bridge over the strait of Gibraltar from Spain to Morocco. There is even greater hope that this technology will be able to be used to build a space elevator (search space elevator for more clarification) as a cheaper means of transport of both people and materials into space. Unfortunately the largest carbon nanotube created thus far is just a few centimeters long. Carbon nanotube research also centers on their ability to conduct electricity making it feasible that they can be used for nanowires in incredibly small and efficient circuitry for future computers and other electronic components. This research is just beginning but it presents an exciting new world for us to look forward to.