Contribution to the Royal Society & Royal Academy of Engineering Study on Nanotechnology

My interest in Nanotechnology is related to medical issues at the nanoscale, principally various possibilities in the field of drug delivery, so my response will largely be confined to the issues in this area.


What is Nanoscience and Nanotechnology?


Nanoscience and nanotechnology is usually defined as science and technology at a nanoscale, which is a fairly flexible definition, and could include materials up to the 1000nm scale, although it is more normally regarded as scales up to 10 or 100nm. Being technologies of scale, there are obviously a diverse range of technologies which could claim a place in nanotechnology. Many of these fields were active before the word nanotechnology became commonplace, and the cynical may say that this collection of ideas is more just a sexy term to attract publicity and funding than a branch of science and technology.

In general terms, this scale is the scale of molecules, particularly macromolecules, aggregates of molecules or small particles, or other structures at this scale. Consequently, nanoscience or nanotechnology will be the science and engineering relating to these scales of matter, which could be conceived of either as assembly into these types of structures (bottom up technologies), or grinding, etching or fabrication of materials or devices (top down technologies).


Applications of Nanotechnology


Drug delivery, the formulation of constructs to improve the effectiveness of drugs by delivering them to disease sites more efficiently, is a particular area of interest which comes under the nanotechnology umbrella. There are a number of technologies which are competing to improve drug delivery particularly in the areas of cancer and inflammatory diseases. In these disease sites, the vasculature can become leaky allowing materials in the nanosize range to exit from the vasculature and leak into these tissues, leading to a selective accumulation compared to normal non-diseased tissues. Conventional drug molecules, are designed to get everywhere in the body, and exert their effects by selective action on target molecules in diseased tissues. However, for many anti-cancer and anti-inflammatory drugs which have serious side effects mediated in normal tissues, these types of technologies offer a particular advantage. There are a range of technologies which could potentially deliver drugs in this size range including large macromolecules like antibodies, soluble polymers, micelles, liposomes and small particles. Additionally, gene therapy requires the delivery of plasmid sized chunks of DNA which also fall into this size range, so delivering pieces of DNA will naturally fall into this definition of nanotechnology. DNA delivery particles will require a range of functional properties or triggers incorporated to deliver the DNA to the nucleus of the cell for the DNA to do its job.

The downside to using particles for drug delivery is that the body has evolved sophisticated defences to attack particles, which would usually be invading microorganisms. This can be overcome by coating particles with very hydrophilic polymers like Poly(ethylene glycol) to prevent them being recognised. These coatings could also be said to be in the nanotechnology range, as the surface properties over about 10nm from the particle surface are important in imparting the correct properties to nanosized drug delivery systems. So for drug delivery, the importance is not only particles but also the structure, and incorporation of other materials into the particles in a controlled and structured manner. The key areas of science to be able to achieve these objectives will be an understanding of how collections of molecules and macromolecules can be assembled effectively. So an understanding of the interactions between different molecules, and in particular how these collections of molecules can be self assembled or condense together to form the desired structures in bulk.

 

Potential for Health, Safety and Environmental impacts

In general it is difficult to see how materials or constructs of a particular size constitute a particular health or environmental problem. As nanotechnology is not a single technology but a collection of technologies, there seems to be no overall principle by which we should expect these technologies as a collection to have a particular health, environmental or safety impact. If we compare nanotechnology with GM technologies and products, one can understand the concerns of the public where the possibilities of new and potentially deleterious life forms or pathogens could be created through manipulation of the controlling force for life. However, there is no such new generic danger apparent from Nanotechnology. The nature of different materials used in nanotechnology, or specific technologies within nanoscience may have individual risks, but these should be dealt with separately not collectively.



Social and ethical issues surrounding Nanotechnology

By analogy once more with GM products, many scientific issues have been raised against GM, but in many cases these are really substitutes for underlying social and economic issues. These issues are diverse such as access to the technologies, exploitation of genetic materials borrowed from other cultures, monopoly rights exploited by a few multinational companies, traditional existing alternative technologies being eliminated from the marketplace. I believe it is these areas that are most likely to cause problems with nanotechnologies. Many of the mainstream nanotechnologies relate to the semiconductor and IT industry. These industries already control and have monopolies over our computers and computer systems which have already caused some disquiet in certain circles (e.g. anti-trust investigations against microsoft). It is possible that in my area of work great things may be claimed for nanotechnology which are in essence a continuation of older work in colloid science. Will this be seen in a similar vein to the use of GM technologies instead of traditional breeding programmes?

 

Areas where additional regulation needs to be considered

It is possible to see from currently known science that are a few areas of particular danger which may merit attention. Materials as they become more finely divided, do acquire different properties, e.g. ability to penetrate into different tissues as seen in drug delivery systems. These may pose problems e.g. toxicity through skin absorption (most likely through existing cuts and abrasions), or inhalation and absorption through the lung. As materials become smaller, effects will be exacerbated, as finely divided materials dissolve most easily so may cause a more rapid spread of toxic finely divided particles. Also the increased fire hazards of finely divided particles are well appreciated. We have been dealing with materials of different sizes already for over a century. At the molecular scale chemistry has manipulated small molecules in bulk, so pushing around individual atoms at the molecular scale is unlikely to cause any new problems there. There are already many technologies at the micro scale (above 10-6m) e.g. powders, microparticles etc, and these also are not known to cause particular generic problems other than through inhalation and lung damage. Materials in the nanosize range have traditionally been referred to as colloids, and this scale of materials in the middle has not so far shown any particular problems. Overall therefore, it is difficult to conceive of what new problems nanotechnologies may cause, but it seems unlikely that nanotechnology poses greater dangers than other chemically based technologies, or that will require additional legislation to deal with.

Dr Martin Garnett
School of Pharmaceutical Sciences
University of Nottingham, UK