chemical biology

Taking a dinosaur’s name in vain.

This is my first post here so imagine my excitement when I came across this attention grabbing title from the JACS press room “Could “advanced” dinosaurs rule other planets?”. Something cool to write about on my first day! Excellent.

So of I trotted to look at the paper that was the bases of the press release. It has the more mundane title “Evidence for the Likely Origin of Homochirality in Amino Acids, Sugars, and Nucleosides on Prebiotic Earth”.

What’s this got to do with dinosaurs I thought? Best delve a little deeper into the paper.

The paper describes how the homochirality of sugars and amino acids in life on Earth may have originated from a small excess of L-amino acids and D-sugars in meteorites.  These then seeded early life, leading to their near total dominance in life as we know it.

Sorry, still no idea what this has to do with dinosaurs. The paper is pretty interesting in it self, but I still don’t get the press release. I’d best read a little further .

Ahh, it turns out that astronomers think that neutron stars may act like cyclotrons and produce circularly polarized light. And if this light has enough energy it could account for the deracemization of amino acids on asteroids.

Still no dinosaurs.

OK, maybe the link with dinos will be clearer in the conclusions.

“An implication from this work is that elsewhere in the universe there could be life forms based on D amino acids and L sugars depending on the chirality of circular polarized light in that sector of the universe …”

Wow, that’s pretty cool (no Dinosaurs though), but it goes on..

“ Such life forms could well be advanced versions of dinosaurs, if mammals did not have the good fortune to have the dinosaurs wiped out by an asteroidal collision, as on Earth”.

WHAT! THAT’S IT! Can somebody please explain to me how we get from homochirality of life to that!

Is it just me or does this smack of blatantly sticking an irrelevant reference to dinosaurs in the conclusion in an attempt to get some press coverage?

Maybe we could all try it. Here goes, the new conclusion from my last paper.

“In contrast, conventional NMR spectroscopy would require several months to collect the same quantity and quality of data. This massive boast in NMR signals could one day mean that we will be able to collect NMR spectra of scarce dinosaur proteins”

By April 11, 2012 11 comments chemical biology, opinion, science news

Eating Carbon Nanotubes


Fathi Moussa

Lon Wilson

Last year I covered Khodakovskaya et al.’s paper regarding the benefits of growing tomatoes in carbon nanotubes (CNT).[CB] At the time I was concerned with the potential health risks associated from eating carbon nanotubes, but today in ACS Nano my concerns are alleviated. A paper from Lon Wilson’s and Fathi Moussa’s research groups discusses the effects from administering oral doses of carbon nanotubes (concentrations as high as 1g of CNT per kg body weight) to Swiss mice.[ACS Nano] The authors summarize their work the best.

CNT materials did not induce any abnormalities in the pathological examination. Thus, under these conditions, the lowest lethal dose (LDLo) is greater than 1000 mg/kg b.w. in Swiss mice.


So feel free to eat all the CNTs you want in lab, assuming they are not functionalized, you do it only once, and you limit yourself to single walled carbon nanotubes. I think partly because the results of the oral administration of CNTs went without any interesting side effects to present, the authors also looked into what happens when you inject CNTs into the peritoneal cavity of mice.

The image on the left is the control while the image on the right is 14 days after injecting mice with CNTs at a concentration of 1g CNT per kg of mouse. Although it looks sickly, the mice injected with the high concentration of CNTs did not die. Well…, not from the CNTs anyways.

Link to paper: In Vivo Behavior of Large Doses of Ultrashort and Full-Length Single-Walled Carbon Nanotubes after Oral and Intraperitoneal Administration to Swiss Mice (ACS Nano)

Mitch

By February 23, 2010 9 comments chemical biology, materials chemistry

The Birth of NanoAgriculture


Mariya Khodakovskaya
alex-biris-thumb
Alexandru Biris

Update (5/30/13, azmanam): The paper referenced in this article was retracted in August 2012 for “unacceptable redundant inclusion of text and graphics from two works previously published in other journals.”

http://pubs.acs.org/doi/abs/10.1021/nn302965w

http://retractionwatch.wordpress.com/2012/09/26/reused-figures-lead-to-two-chemistry-retractions-one-correction

There has been a lot of concern over the health effects arising from the burgeoning field of nanotechnology, David Barden covered one such paper focusing on nanotube production in Highlights in Chemical Science earlier this month.[HCS] What hasn’t been as discussed are the potential health benefits of carbon nanotubes (CNTs). In a paper released yesterday in ACS Nano, Mariya Khodakovskaya & Alexandru Biris (+coauthors) found that tomato seeds grown in a medium of carbon nanotubes germinated and grew more efficiently than their control group brethren.[ACS Nano] This result is spectacularly seen from the image below.


After 27 days of growth.

The tomatoes grown in carbon nanotubes weighed more, grew longer stems, and matured faster. The authors reason this is due to the carbon nanotubes facilitating water intake, however the evidence provided doesn’t prove this beyond a reasonable doubt. Although I wouldn’t recommend eating these tomatoes just yet, one could still use the increase in plant biomass and efficiency for biofuels and related projects.

Link to paper: Carbon Nanotubes Are Able To Penetrate Plant Seed Coat and Dramatically Affect Seed Germination and Plant Growth

Mitch

By September 23, 2009 7 comments chemical biology, materials chemistry

Teen Chemist and Splenda

For as long as artificial sweeteners have been used, there has been a varying level of controversy over the safety of their use; both for humans and the environment in general. Saccharin and Aspartame have been plagued by health concerns raised by researchers for decades. Most studies have shown that only in very high concentrations are they dangerous, however few long term (>10 years) studies have been completed, so lower dose, chronic exposure has yet to be rigorously  investigated. Currently, most diet sodas use aspartame and saccharin, including my favorite, Coke Zero. Another very popular sugar substitute, sucralose has begun to steal the spotlight away from aspartame in recent years, taking over popular drinks like Crystal Light, Tim Horton’s and Starbucks coffee.

The chlorinated sugar substitute called sucralose 200px-sucralose2svg(commercially marketed as Splenda (TM)) was first synthesized in 1976, as part of a collaboration between Queen Elizabeth College in London and the Tate and Lyle Chemical Company. It is manufactured by the selective chlorination of sucrose, in which three of the hydroxyl groups are replaced with chlorine atoms. Supposedly the graduate student, Shashikant Phadnis, working on the synthesis misunderstood his professor’s request to test the chemical as a request to taste the chemical. Just goes to show, sometimes to make a lucrative discovery, a chemist must take the ultimate test!

Whatever happened, it has been found that Sucralose is approximately 600 times sweeter than sucrose, and since being introduced in the USA in 1998, has become one of the leading sweeteners on the market. One of the main reasons for this is that studies have shown that sucralose is highly stable; it doesn’t break down easily due to heat so cooking with it is safe. It also doesn’t dechlorinate over time, photo degrade under visible light, or biodegrade with common bacteria. It is also very insoluble in fat cells, so all of us Americans don’t have to worry about getting a heart attack on the treadmill (at least not from sucralose!). In fact, sucralose is so darn stable, it doesn’t even get broken down in waste treatment plants.

Meet Smitha Ramakrishna, a senior at Corona del Sol High School in Chandler, Arizona, who has been doing research at Arizona State University about sucralose’s inability to be broken down and how this make affect the environment. At only 17 years of age, she has been researching sucralose for nearly 2 years, as part of her greater goal of trying to help with global water issues. She also founded an organization named AWAKE, which is dedicated to increasing her community’s awareness about water-related issues.

She has found that after subjecting sucralose to treatments similar to those used by waste water treatment plants, the sweetener resisted bacterial digestion. Only after a long time and under UV irradiation in the presence of high concentrations of titanium oxide (TiO2) did the sugar break down. Considering that few plants use these methods, the majority of sucralose in wastewater enters the ecosystem. She doesn’t say for sure what effect this will have, but says that preliminary studies suggest high concentrations of sucralose may poison fish.

See more here: That Splenda you’re drinking will be in our water supply for a while

Personally, I think people should use xylitol more. First studied in the 1970’s, almost no negative effects have been found due to ingestion of even 400+ grams a day (imagine 400+ grams of sugar! BLECH!) and many positive health effects have been proven ranging from plaque-reducing effects to boosting your immune system. It is about as sweet as sucrose, and has 2/3 the caloric content.

That said, I am still gonna go get me a coke zero.