Month: August 2007

Wound Healing and Super Cabbage

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This week in The ChemWeb Alchemist, I report how Illinois chemists have developed a novel catalytic approach that side-steps functional group modifications to streamline organic syntheses. The Alchemist also discovers that a serendipitous finding leads to a bright spot in observing electron transfer in single molecules under the scanning tunneling microscope. While mixed signals appear in C&EN regarding the safety of bisphenol A.

In Africa, extracts of the leaves of the so-called hemorrhage plant could provide medical science with a new approach to faster, cleaner wound healing. Finally this week, upping the glucosinolate content of an entirely different group of plants, brassica crops, might not only help cabbage, broccoli, and cauliflower ward off pests and so save on pesticide use, but could also boost the cancer-fighting powers of these foods for people who eat them.

Speedy synthesis – University of Illinois chemists hope to meet the efficiency challenge in organic chemistry by exploiting a newly developed class of carbon-hydrogen catalyst. Christina White and her colleagues are creating a new chemical toolbox of highly selective and reactive catalysts that are tolerant of other functionality. “By offering fewer steps, fewer functional group manipulations and higher yields, this toolbox will change the way chemists make molecules,” White claims. A palladium/sulfoxide catalyst provides the team with a selective method for directly inserting nitrogen functionality into relatively inert C-H bonds without having to manipulate functional groups. The team has reported streamlined syntheses of various compounds, including a peptidase inhibitor drug candidate, a nucleotide-sugar L-galactose, and the chemotherapeutic reagent acosamine. She and her colleagues are currently applying the technology to synthesizing the antibiotic erythromycin A.

Read this week’s Alchemist for summaries and direct links to all featured chemistry news

Short Chicken Wire Roll Up

Double wall chickens

In a past life I was deputy editor on the RSC journal Chemical Communications and recall the excitement and tension around the time we published Sir Harry Kroto’s pioneering fullerene paper. At the time, there were all kinds of imaginative plans emerging for what might be done with these odd all-carbon soccerball shaped molecules.

However, it was not the spherical, nor the spheroidal, fullerenes that became the darlings of materials scientists and nanotechnologists the world over. Instead it was their stretched cousins – the carbon nanotubes. Resembling a sub-microscopic roll of chicken wire, these long, hollow molecules have been touted as potential components for the future of microelectronics, as conducting connectors for nano devices, as catalysts and even as smart drug delivery agents.

Chemical scientists have developed various methods for synthesising nanotubes that are just a single atom thick, others that have a double wall, like two layers of rolled up chickenwire, all just a few nanometres in cross-sectional diameter. However, according to researchers writing in the International Journal of Nanotechnology (2007, 4, 618-633) there are no widely accepted techniques for producing useful quantities of short nanotubes of a specific length.

Simon Smart, G.Q. Lu, and D.J. Martin of the Australian Institute for Bioengineering and Nanotechnology, University of Queensland, Australia, and W.C. Ren and H.M. Cheng of Shenyang National Laboratory for Materials Science, of the Chinese Academy of Sciences, have now devised a production method for making shortened double-walled carbon nanotubes using by high-energy ball milling.

On the everyday scale of things, a ball mill is type of cylindrical grinder within which are loose balls (ceramic, steel, or flint pebbles, commonly) and to which is added the material to be milled. The ideal technique for shortening nanotubes has to have three characteristics, say the researchers. First, from a practical point of view, it should be able to produce gram quantities of individual samples. Secondly, it has to be able to shorten the nanotubes without significantly impacting on their purity of destroying the nanotubes entirely. Finally, the method has to be controllable so that it can shorten the nanotubes reproducibly and accurately.

Other researchers have attempted to shorten nanotubes using ultrasonic agitation, chemical cutting techniques, and ball milling. Ultrasound is not particularly controllable in terms of producing large quantities of nanotubes of a similar length while chemical methods are convoluted and can damage the nanotube walls. So, Smart and colleagues have focused on ball milling. This technique requires no chemical additives and can have a high throughput.

The team tested the shortened nanotubes using transmission electron microscopy (TEM), scanning electron microscopy (SEM), Raman spectroscopy, thermogravimetric analysis (TGA) and X-ray photoelectron spectroscopy (XPS).

The researchers now plan to use their ball-milled carbon nanotubes in novel polymer nanocomposite materials and to carry out toxicological studies. It should be possible to disperse these shorter nanotubes much more effectively in composite materials, explain the researchers, because they do not form bundles so readily as long nanotubes but would still endow the nanocomposite with novel strength and flexibility properties. “In fact, early results are showing that in polyurethane elastomers, the shorter nanotubes out perform the longer ones,” Smart told Sciencebase. He adds that, “These materials are most suited towards polymer nanocomposite materials. The presence of
carbonyl functional groups on the sidewalls does lend itself towards further chemistry and possible applications in drug delivery or sensing applications. However, at this stage of research, the ball milling process induces too many defects for use in applications that utilize the nanotubes
unique electronic properties.”

Giving good head line

Giving good head lineI was discussing press releases and headline writing recently with a technology writer friend. One thing that many first-time authors and the people they write about are blissfully unaware is that magazines and newspapers usually employ specific people, sub-editors and headline writers, to chop up any author’s glorious prose and to stick an entirely different title up-top and call it the headline. This is not a criticism, it’s just a fact of journalism.

However, it often comes as a shock to many new writers who may have imagined their witty strapline needed no tweaking or editing all. A shock, you say? Well, certainly. The headline is designed to both grab your attention and primarily make you want to buy the publication with the intention of reading the article. If it is left as a flat abstract or esoteric phrase who’s going to grab the paper?

Compare and contrast: “Member of royal household indulges in illicit substance by inhalation” with “Dopey Prince”

The former is obviously a ludicrously overblown working title that an author might cut down to something like “Royal admits to smoking cannabis”, but a subbie would prefer something even crisper, with a deliberate ambiguity about whom the article is talking. Is it the artist formerly known as Prince and now known as Prince again but giving it away for free? Or is it one of the Royal Family? If so, which one? Intrigued? You will be. Subeditors and headline writers are the royals of keyword use, they are now and always were, even before we were all worrying about link bait and search engine optimisation online.

Anyway, the upshot of this discussion was that I thought I would dig out some of my old cuttings from the The Grauniad and elsewhere and do a comparison of the titles I originally gave the article and the final headlines used by the paper…if there’s an online link to them, I’ll point to those too, so you can get to read what I had to say (assuming the headline grabs you). In fact, now that I think of it, maybe I should not say which one is which and simply link to the online article (where there is one) from both my title and the final headline. You can guess which you think it will be and find out when you make the click.

A blue light for change – Guardian – The butterfly effect

Be of good cheer – Guardian – Bread and stuffing chemistry

The Genome Chose Its Alphabet With Care – Science – Genetic alphabet soup

A cup of tea is no mug’s game – Guardian – Tea – best drink of the day for diabetics

Sweaty way to beat stress – Guardian – Sweaty stress busters

Shy Chemicals Offer a Solution – Science – Greening chemistry with non-stick molecules

The dating game – Guardian – A trunk call to be sniffed at

Finally, sometimes the sub-editor merely tweaks a title as in the case of my article in the July-August issue of StarDate magazine:

Cosmic Efforts Shed Light on Dark Universe – Cosmic Efforts Shed Light on Dark Energy

I’ll add a few more when the opportunity arises. I have dozens in the archives but will have to dig out backup discs to find the original pre-edited article and accompanying title.

Biomarkers Point to Earlier Treatment for Parkinsons

Medical diagnostics

Parkinson’s disease and Alzheimer’s disease are devastating illnesses. The former steals a person’s control of their body while the latter takes away their mind. There are no cures. But new research into biologic rhythms now underway could help the medical profession find diagnostic tools that spot the early stages of the disease sooner, rather than later.

“Both Parkinson’s disease (PD) and Alzheimer’s disease (AD) have a profound effect on biologic rhythms,” Otto Appenzeller told me, “Both diseases are recognized clinically only after a considerable loss of nerve cells, which might take years. For example, the clinical diagnosis of PD is only possible after about 70% of nerve cells disappear in a specific region of the brain at risk of complete devastation by the time the disease is easily diagnosed by physicians.”

Appenzeller and his colleagues at the New Mexico Health Enhancement and Marathon Clinics Research Foundation and the University of New Mexico in Albuquerque, USA, together with co-workers at the Universita degli Studi di Milano, in Italy, are using spectral analysis of stable isotope ratios to track changes in hair and tooth enamel that could lead to earlier diagnostics for neurodegenerative diseases such as Parkinson’s and Alzheimer’s disease.

Appenzeller points out that there is therefore a great urgency to find “biomarkers” that would betray the presence of these and other diseases before they are clinically diagnosed. Such biomarkers could allow treatments to be started sooner and potentially save nerve cells and so alter the course of the illness. “Since hair (and teeth) preserve a record of biologic rhythms spanning several years, disturbances in these rhythms attributed to PD or AD as gleaned from stable isotope ratios may provide an important hint of disease processes at work in a given subject,” he told me.

The Michael J Fox Foundation for research into PD has recently launched a “request for research proposals” entitled Biomarkers for Parkinson’s disease, for which the foundation has allocated US$1million (about £500k). “At present, there are no good drugs available that can save nerve cells from destruction but the pharmaceutical companies are working feverishly in this area,” Appenzeller said.

Wine and Health

It’s that time of the week again, time to crack open a bottle to share and time to wonder about the health effects or otherwise of wine. There have been hints for years that various antioxidant components of wine, and red wine in particular, could be protective against cardiovascular disease (heart attacks and stroke, basically). Although I’ve reported on some of those studies, I’ve always been rather skeptical of the claims they make because fundamentally imbibing large quantities of a volatile organic solvent (VOC) (ethanol) is not really a good idea (think brain and liver damage). More to the point, we need free radicals to help our immune systems ward off pathogens, so couldn’t stifling them cause more problems than they fix.

Anyway, toxicity is always about dose. However, anyone who has suffered the morning after the night before will know all about the toxic side effects and the downside of ingesting ethanol. the downside is far more well documented in fact than any of the purported benefits of the antioxidant congeners.

So well document in fact are the side-effects that governments are considering making health warnings on booze obligatory in the same way that they are for cigarettes in many places. It makes sense, even if some people cry: “Nanny state gone mad!”. At least those who are unaware of the serious risks associated with overindulging in flavoured ethanol solutions will hopefully get the message and make the right choice.

Now, where did I put that corkscrew..?

Copper Blues

Copper antioxidants

Lots of people take multivitamins, mineral supplements, and a vast range of antioxidants? But, do they improve your health and wellbeing above and beyond what you could achieve with a well-balanced diet, plenty of fresh air and exercise? In some instances, the jury is still out, although recent evidence suggests that deliberately taking super doses of vitamin C (ascorbic acid) will not, despite the proclamations of the late, great Linus Pauling, protect you from the ravages of the common cold.

There is also the issue of contraindications, not only are some fat-soluble vitamins and minerals toxic at high dose because they can accumulate in the body, there are some supplements and so-called natural tonics, that can interfere with prescription medicines. It is not a good idea, for instance to take the purported natural antidepressant St John’s wort with prescribes serotonin reuptake inhibitors (SSRIs) used in treating depression. Why this is so remains unclear and becomes an especially problematic puzzle to solve given the increasing evidence that the active ingredient in SJW, hypericin, does not in fact inhibit the reuptake of serotonin in the brain anyway!

Now, researchers in Italy have demonstrated that copper, an essential element in our bodies, interferes with our natural internal antioxidants and those many people ingest in the form of over-the-counter health boosters.

Chemists Luigi Campanella and Maria Costanza of the University
of Rome La Sapienza and colleague Marcelo Enrique Conti in the Development Studies Research Centre (SPES) have used an electrical technique known as cyclic voltammetry, to investigate the oxidising and reducing behaviour of antioxidants in the presence of copper ions. Their results, published recently in the International Journal of Environment and Health (2007, 1, 328-340) could make worrying reading for anyone popping health pills on a regular basis.

Copper ions have antioxidant activity. Indeed, copper is an essential nutrient for humans because it works in the regulation of antioxidant enzymes to protect out tissues from highly reactive oxygen free radicals that would otherwise tear apart the biomolecules from which our cells are composed. However, the electrical tests also suggest that the presence of copper is a double-edged sword, because it can also promote the kind of oxidising reactions that cause such damage. “the final effect [of taking supplemental copper] may not be as positive as expected,” the researchers say, and may also be associated with “the risk of toxic secondary effects.”

If oxidants and antioxidants are not balanced, then our cells are exposed to harmful oxidative stress, biochemical damage, and ultimately cell death. There are numerous protective agents, including superoxidodismutase (SOD), glutathione peroxidase (GSHPx), catalase enzymes and transferrin, ferrithin and ceruloplasmin (these bond to iron and copper ions as the activating metals of radical reactions) and the secondary ones such as all the molecules, including antioxidant vitamins, that are able to stop the reactions started by free radicals. When these agents are overwhelmed, cell damage ensues, and this plays an important role in the beginning of diseases, including cardiovascular disease, cancer and degenerative diseases.

The team points out that further studies are needed to verify the results of their electrical tests at the clinical level. What seems to emerge from the present laboratory study is that copper ions sometimes act as antioxidants and sometimes as pro-oxidants. “These conclusions disagree with the current theories that copper ions show only antioxidant action,” the researchers say.

Blue-Green Porphyrin Flip

A molecular Möbius strip that can flip between single-sided and double-sided modes has been synthesised by chemists in Poland without snapping the ring.

Lechoslaw Latos-Grazynski and his colleagues at the University of Wroclaw explain that for a molecule to be defined as aromatic it must exist as a near planar ring and have a pi electron system that allows for the free movement of electron pairs between alternating double and single bonds – the classic Hückel topology. Even rings that are twisted into a figure eight can have this topology. However, a molecule with a 180 degree twist has the Möbius topology and there is no distinction between the “upper and lower” pi electron cloud to give it the properties of aromaticity.

The team worked with an expanded porphyrin analogue – A,D-di-p-benzi[28]hexaphyrin(1.1.1.1.1.1) with a figure-of-eight shape having two phenylene six-membered carbon rings at the crossover point. Whether or not these rings are perpendicular or parallel dictates whether or not the molecule is Hückel or Möbius.

Finding molecules of this type are of fundamental importance to understanding molecular topology and aromaticity but the color change inherent in the flip might also allow the compound to be used as an indicator for the presence of other species in a solution, for instance.

You can read more about the study in the current issue of the SpectroscopyNOW.com ezine and see a blue-green morph of Prof Latos-Grazynski.

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Finding ET

Horsehead nebulaResearch in the field of exobiology relies on one of the biggest assumptions we make about the universe – that we are not alone, that there could be life on worlds other than the Earth.

However, one assumption we should not make about life elsewhere in the universe is that it uses the same templates and building blocks as life on earth. There is no reason to presume that life on another planet will use the molecules resembling nucleic acids, DNA and RNA, to encode its genetic information. Life may not be limited to existing on small blue worlds. There is an amazing diversity of life on earth from the obvious insects, fish, mammals, to vast fungal domains and microbes that live on boiling sulfur deep in the sea or underground. Some of these species were not even dreamed of fifty years ago, and may only scratch the surface of this single planet we call Earth.

There is now indirect theoretical evidence to suggest that inorganic forms of life might exist in plasma clouds between the stars, even, or that water need not be the universal solvent of life at all. So, any discussion of exobiology always comes back to that first question – would we recognize alien life if we saw it?

A recent report published by the US National Research Council (NRC)suggests that scientists focus at least some of their efforts on “weird” life, that is, the possibility of life that does not confirm to the standard terrestrial chemical blueprint. You can read my further thoughts on this in the August issue of our physical sciences newsletter, Intute Spotight.

Also in the August issue: Casting pearls – Despite its common use in jewellery and for decoration, mother-of-pearl, or nacre, could be more suited to engineering applications. This natural material found lining the shells of sea creatures, such as oysters and abalones, is 3000 times less susceptible to fractures than the mineral, aragonite, from which it is made. Amazingly, driving a heavy lorry over an abalone shell will crack the shell itself but not the nacre lining.

Now, physicist Pupa Gilbert of the University of Wisconsin-Madison, and her colleagues there and at the Institute for the Physics of Complex Matter in Switzerland and the UW-Madison Synchrotron Radiation Center have taken the first steps to understanding how nacre forms and the secret of its great strength.

Finally, “Imagine a super-sized bald eagle with a 7 metre wingspan,” suggests Sankar Chatterjee of Texas Tech University, “It would darken the sky. It was a very aggressive bird that flew over the pampas of Argentina to sweep down from the sky and seize large prey with a formidable beak.” He and his colleagues have used computer software designed to model helicopter flight to reveal that this giant bird – Argentavis magnificens – could not take off by flapping its wings only. Instead, it needed a launch pad on a high precipice that would allow it to catch rising thermals so it could soar into the air and undertake 300 km trips with ease.

Hemp Help for Everglades

Atrazine structure

Atrazine, a herbicide, and some of its degradation products could seep into groundwater and impair water quality across the Florida Everglades, according to Scientists from the USDA-Agricultural Research Service (ARS) and University of Florida. The team reports details of its studies into specific groundwater risk from atrazine in the September issue of the Journal of Environmental Quality.

In the same report, Thomas Potter and colleagues also report how they may have discovered a solution to the potential problem – a herbaceous annual that grows to two meters: sunn hemp.

The studies focused on sweet corn production and investigated whether fields with a highly vigorous cover crop would reduce the impact of herbicide use on the environment. Sunn hemp planted during uncultivated summer periods was found to be effective in reducing weeds and leaching while at the same time enriching the soil. Sunn hemp, not to be confused with cannabis hemp, can be grown to prevent soil erosion, as high-protein forage. The older plants can be used to make cloth, twine, and rope.

InChI=1/C8H14ClN5/c1-4-10-7-12-6(9)13-8(14-7)11-5(2)3/h5H,4H2,1-3H3,(H2,10,11,12,13,14)/f/h10-11H