tectosquares

I am writing this blog as I procrastinate writing the final exam for my BioNano class this fall. During the class, student picked current peer reviewed journal articles and presented them in a short Pecha Kucha format. This means presenting 20 PPT with 20 sec per slide. Topics ranged from applications of gold nanoparticles for lung cancer detection, the effects of feeding Buckyballs to mice, and antimicrobial properties of nanosilver. Students in the class were required to read the papers chosen by their classmates and write up a list of questions (collected for a grade). I thought the format worked out well. Very short presentations followed by fairly animated dialogue (for a 9:30 AM class).

Since the students chose the articles, some were very familiar to me but some were quite unexpected. One of the more interesting topics that I learned about was making tectosquares that are RNA sequences that self assemble into ladder-like nanostructures. In the paper listed below, they used nanogold particles to quantify the spacing. Very Elegant.
Controlled Spacing of Cationic Gold Nanoparticles by Nanocrown RNA
Alexey Y. Koyfman,§,† Gary Braun,§ Sergei Magonov,‡ Arkadiusz Chworos,§ Norbert O. Reich,§,† and Luc Jaeger*,§,† J. AM. CHEM. SOC. 2005, 127, 11886-11887

ice and water

The phase transitions between frozen and liquid H2O are so critical to human survivial that we have developed words - Ice and water - To describe these important but not so different events.
Normally phase changes are described by simple subscripts but water is different because it is so vital. How is ice different from liquid water?
Look at these simulations
http://iclcs.illinois.edu/index.php/chemistry-simulations

Why is water so unique?

A year or two ago, I was involved in a debate with some smart people about water. This wasnt a debate over water purity or the future scarceness of water, both of which are important and compelling topics, but something more fundamental. What is water? How are snowflakes formed? What do we call H2O structures? Does it fall under the category of "self assembly"?

One person on this committee didnt think that water fell into the category of nanotechnology, and it lacked the size dependent properties that we use to define nanotechnology. It was deemed too simple and not as compelling as some of the other topics we were thinking about (nanoelectronics, gold nanoshells, quantum dots). However, we don't really understand water and probing the interactions between water molecules is necessary before we can understand complicated structures and biological systems like transport through cell membranes.

However, if we think of the important characteristics of water like hydrogen bonding, solvation, and how it serves as the basis of life (along with some carbon and nitrogen), then we must realize that understanding the chemistry of water is essential to understanding the future of science. Research on water is not a trivial exploration and this study exemplifies some of the complexity of the substance we take for granted http://pubs.acs.org/doi/abs/10.1021%2Fjp1060792

proton size?

I woke up this morning feeling maybe smaller, maybe less energized. In fact, a new study in Nature calculates that the proton is 4% smaller than previously thought or as this Scientific American headline reads "proton shrinks in size" http://www.scientificamerican.com/article.cfm?id=proton-shrinks-in-size. So perhaps my jeans really do fit better today because my protons are smaller than they were last week.

What do these studies imply? Does this mean that we don't understand the basic structure of the atom as well as we thought? Does a 4% difference matter? Perhaps there was a calculation error and this newest technology that was used in this experiment is just off somewhat. Since now the Rydberg constant would now be different, does this through a glitch into the whole concept of quantum theory? Should we care? While protons are measured in femtometers are a lot smaller than nanometers (1,000,000times), all matter is composed of protons, electrons and neutrons. So when someone says your protons are smaller than they thought, you should take note.

Opportunity to share your ideas about nanotech with the Office of the President

President's Council of Advisors on Science and Technology(PCAST) will be hosting a webcast on nano, bio and information technology. If you go to the OpenPCAST website, http://pcast.ideascale.com/ and submit your ideas. The webcast will be on Tuesday, June 22 from 10 am to 2:30 pm. See the PCAST site for more details. http://www.whitehouse.gov/blog/2010/06/15/polishing-technology-s-golden-triangle

Nanocomposites and everyday things

I just put some Saran wrap on leftovers. Was it Saran or some cheaper knock off? Does it matter? Probably not, since my family will eat it tomorrow regardless (they are not picky). However, if you were packing a product to be shipped around the world, like an expensive pharmaceutical product or even an inexpensive snack, you would care. Time is money - esp. when it is sitting on a store shelf.

How does this relate to the esoteric term, nanocomposites? The cause of most food spoilage is are either microbial or chemical- specifically oxidation. Microbes are relatively large (micron sized), so plastic films easily act as a barrier. A molecule of oxygen, however, is very small (more than 1000 times smaller than a microbe) and can be transported through plastics (also known as polymers) easily. This transport or permeability depends on the solubility of oxygen (or how well it dissolves) in the polymer and its ability to diffuse or move through the polymer.

Different polymers have vastly different gas transport properties and cheap polyethylene (Glad wrap) is much more permeable to gases than polyvinylidene chloride (Saran wrap). However, if you look at the packaging after you finish those chips from the vending machine, you will see that they have an additional layer of aluminum foil that really prevents gas transport.

Recently it has been found that when polymers are sequentially prepared into nanometer thick layer cakes, the barrier properties of the materials improve. Because polymers are glass-like structures, they tend to change or relax over time. This relaxation basically allows the polymer molecules to get closer together and this more compact structure blocks the transport of gas through the material. So controlling the nanostructure of polymer films could increase the shelf life of products and potentially eliminate the need for the expensive aluminum layer in packaging.

More specifically, a composite in a combination of materials. A polymer with nanosized additives would be called a nanocomposite. Adding nanosized particles to polymers can increase its strength, decrease its weight and improve its barrier properties (or how well it blocks oxygen). The nanosized material could be relatively inert clay materials or potentially antioxidant or antimicrobial particles.

While many people think of packaging as either something for marketing or something that is waste issue, and indeed both are true, good packaging prevents food spoilage and protects the activity of pharmaceutical products. Every day we pack a lunch, save leftovers, open a container from the store. Whether we like it or not, packaging is a part of our everyday lives.

Nanotechnology lectures freely available from CHEM 570 Nanotechnology for Teachers

Dr. John Hutchinson and I taught Nanotechnology for Teachers out of Rice University and The University of Colorado at Boulder in the Spring of 2009 using distance learning software. All of the course content, including cutting edge research presentations from Rice Faculty, Post-Docs and Graduate students are freely available at http://webcast.rice.edu/webcast.php?action=details&event=1724

Fun Nano labs

Synthesizing ferrofluids and liquid crystals are laboratory activities that can be conducted in a 75 minute lab. At Rice University we have incorporated these labs in our freshmen chemistry course and have taught it to teachers in our Nanotechnology for Teachers course. An outline of the protocol is described by Dr. Mary McHale at http://cnx.org/content/m15768/latest/

Stellar Nanotubes

In 2008, carbon nanostructures that looked like long carbon nanotubes were
identified in three meteorites. This was surprising because on earth, the temperatures and pressures associated with making carbon fullerene structures were/are very energy intensive and involve very toxic and/or expensive catalysts. However, scientists are now looking at ways to mimic interstellar reactions to create carbon fullerine structures. http://www.sciencedaily.com/releases/2010/02/100224214434.htm

Which is appropriate because the first carbon fullerene structures that were identified by Kroto, Curl and Smalley at Rice University, were bucky balls or soccerball shaped structures of carbon. The discovery of the buckyball came out of investigations of carbon structures in interstellar space.