It's a Nano-World

Since I have gotten back into reading journals again, or at least perusing their table of contents for papers in which I might be interested, I have noticed a large increase in the number of papers dealing with nano-materials. Perhaps they have been there all along for the past 10 years and I just haven’t been paying attention, but lately it seems that every journal I read has at least one article relating to either carbon nanotubes or nano-titania, if not both. In one week I found reports covering nano-magnets, nano-gold wire, nano-silver, nano-fibers, and nano DNA particles.

The last time I paid any attention to an article about nano-somethings was about 15 years ago, when the authors were proclaiming the advantage of some newly developed alumina nano-powders for use as substrates in automotive catalytic converters. Smaller particles typically have higher surface areas, and high substrate surface areas are often the Holy Grail when it comes to creating highly dispersed Pt or Rh metal catalysts. Unfortunately, it doesn’t matter what the surface area is when you make these catalysts, what matters is the surface area after the catalytic converter has seen 600^oC for many, many miles while experiencing alternating lean and rich environments. Not surprisingly, the alumina nano-powders lost most all their surface area under these conditions, eventually looking very similar to the regular old alumina powders prepared by traditional methods.

Nevertheless, nano-materials sound like an exciting field, but I wonder how often these materials are really novel and how often it is just sexy to use the term “nano.” Samsung has developed a washing machine with supposedly antibacterial properties. Using a silver plate and some electrolysis, apparently 1 trillion silver ions are released into the wash water, supposedly killing bacteria and possibly bonding to the clothes for further antibacterial action over the next 30 days. The general idea is not particularly new, of course. An entire industry has built up around the concept of using very minute amounts of silver as an antibacterial agent, including (very expensive) soaps and food storage containers. What caught my interest was Samsung’s reference to silver ions as nanoparticles. Now it would not surprise me if those 1 trillion silver ions get reduced to metal (nano?) particles with time, but Samsung is specifically applying the word “nanoparticles” to silver ions, which seems, at least to me, to be an incorrect use of the word. Of course Samsung’s marketing department is hardly alone in this. For example, according to Invision International, promoter of Opti-Silver, "’Nano silver’ is the sexy new term for ionic silver." Hmmm… water molecules are less than a nanometer in length (water clusters would be on the order of a few nanometers), I wonder when some bottled water company is going to start calling their product NanoWater (Note to self: trademark the term “NanoWater”). Air molecules are pretty small also – perhaps another marketing opportunity?

Btw, while searching the net for information on alchemical information, I have come across several discussions concerning the benefit of drinking water containing gold nanoparticles. Supposedly, it cures a variety of aliments. Of course, companies have sprung up to meet this important demand.