Tag Archives: UK

White beetles and complex photonic nanostructures

At least one species of white beetles which have excited scientists with their complex nanostructures are native to Southeast Asia according to an Aug. 15, 2014 news item on Nanowerk,

The physical properties of the ultra-white scales on certain species of beetle could be used to make whiter paper, plastics and paints, while using far less material than is used in current manufacturing methods.

The Cyphochilus beetle, which is native to South-East Asia, is whiter than paper, thanks to ultra-thin scales which cover its body. A new investigation of the optical properties of these scales has shown that they are able to scatter light more efficiently than any other biological tissue known, which is how they are able to achieve such a bright whiteness.

An Aug. 15, 2014 University of Cambridge press release (also on EurekAlert), which originated the news item, describes the properties needed to create the optical conditions necessary for the colour white to be seen,

Animals produce colours for several purposes, from camouflage to communication, to mating and thermoregulation. Bright colours are usually produced using pigments, which absorb certain wavelengths of light and reflect others, which our eyes then perceive as colour.

To appear as white, however, a tissue needs to reflect all wavelengths of light with the same efficiency. The ultra-white Cyphochilus and L. Stigma beetles produce this colouration by exploiting the geometry of a dense complex network of chitin – a molecule similar in structure to cellulose, which is found throughout nature, including in the shells of molluscs, the exoskeletons of insects and the cell walls of fungi. The chitin filaments are just a few billionths of a metre thick, and on their own are not particularly good at reflecting light.

The research, a collaboration between the University of Cambridge and the European Laboratory for non-Linear Spectroscopy in Italy has shown that the beetles have optimised their internal structure in order to produce maximum white with minimum material, like a painter who needs to whiten a wall with a very small quantity of paint. This efficiency is particularly important for insects that fly, as it makes them lighter.

Here’s what the Cyphochilus beetle looks like,

Cyphochilus beetle Credit: Lorenzo Cortese and Silvia Vignolini

Cyphochilus beetle Credit: Lorenzo Cortese and Silvia Vignolini Courtesy University of Cambridge

The press release goes on to describe the beetle’s optical properties in greater detail,

Over millions of years of evolution the beetles have developed a compressed network of chitin filaments. This network is directionally-dependent, or anisotropic, which allows high intensities of reflected light for all colours at the same time, resulting in a very intense white with very little material.

“Current technology is not able to produce a coating as white as these beetles can in such a thin layer,” said Dr Silvia Vignolini of the University’s Cavendish Laboratory, who led the research. “In order to survive, these beetles need to optimise their optical response but this comes with the strong constraint of using as little material as possible in order to save energy and to keep the scales light enough in order to fly. Curiously, these beetles succeed in this task using chitin, which has a relatively low refractive index.”

The secret lies in the beetles’ nanostructures,

Exactly how this could be possible remained unclear up to now. The researchers studied how light propagates in the white scales, quantitatively measuring their scattering strength for the first time and demonstrating that they scatter light more efficiently than any other low-refractive-index material yet known.

“These scales have a structure that is truly complex since it gives rise to something that is more than the sum of its parts,” said co-author Dr Matteo Burresi of the Italian National Institute of Optics in Florence. “Our simulations show that a randomly packed collection of its constituent elements by itself is not sufficient to achieve the degree of brightness that we observe.”

Here’s a link to and a citation for the paper,

Bright-White Beetle Scales Optimise Multiple Scattering of Light by Matteo Burresi, Lorenzo Cortese, Lorenzo Pattelli, Mathias Kolle, Peter Vukusic, Diederik S. Wiersma, Ullrich Steiner, & Silvia Vignolini.  Scientific Reports 4, Article number: 6075 doi:10.1038/srep06075 Published 15 August 2014

This paper is open access.

Science and the arts: a science rap promotes civil discussion about science and religion; a science movie and a play; and a chemistry article about authenticating a Lawren Harris painting

Canadian-born rapper of science and many other topics, Baba Brinkman sent me an update about his current doings (first mentioned in an Aug. 1, 2014 posting featuring his appearances at the 2014 Edinburgh Fringe Festival, his Rap Guide to Religion being debuted at the Fringe, and his Kickstarter campaign to raise money for the creation of an animated rap album of his news Rap Guide to Religion), Note: Links have been removed,

Greetings from Edinburgh! In the past two and half weeks I’ve done fifteen performances of The Rap Guide to Religion for a steadily building audience here at the Fringe, and we recently had a whole pile of awesome reviews published, which I will excerpt below, but first a funny story.

Yesterday [August 14, 2014] BBC [British Broadcasting Corporation] Sunday Morning TV was in to film my performance. They had a scheme to send a right wing conservative Christian to the show and then film us having an argument afterwards. The man they sent certainly has the credentials. Reverend George Hargreaves is a Pentecostal Minister and former leader of the UK Christian Party, as well as a young earth creationist and strong opponent of abortion and homosexuality. He led the protests that got “Jerry Springer the Opera” shut down in London a few years back, and is on record as saying that religion is not an appropriate subject for comedy. Before he converted to Christianity, the man was also a DJ and producer of pop music for the London gay scene, interesting background.

So after an hour of cracking jokes at religion’s expense, declaring myself an unapologetic atheist, and explaining why evolutionary science gives a perfectly satisfying naturalistic account of where religion comes from, I sat down with Reverend George and was gobsmacked when he started the interview with: “I don’t know if we’re going to have anything to debate about… I LOVED your show!” We talked for half an hour with the cameras rolling and at one point George said “I don’t know what we disagree about,” so I asked him: “Do you think one of your ancestors was a fish?” He declared that statement a fishy story and denied it, and then we found much to disagree about.

I honestly thought I had written a hard-hitting, provocative and controversial show, but it turns out the religious are loving it as much as the nonbelievers – and I’m not sure how I feel about that. I asked Reverend George why he wasn’t offended, even though he’s officially against comedy that targets religion, and he told me it’s because I take the religious worldview seriously, instead of lazily dismissing it as delusional. The key word here is “lazily” rather than “delusional” because I don’t pull punches about religion being a series of delusions, but I don’t think those delusions are pointless. I think they have evolved (culturally and genetically) to solve adaptive problems in the past, and for religious people accustomed to atheists being derisive and dismissive that’s a (semi) validating perspective.

To listen to songs from The Rap Guide to Religion, you need to back my Kickstarter campaign so I can raise the money to produce a proper record. To check out what the critics here in Edinburgh have to say about my take on religion, read on. And if you want to help organize a gig somewhere, just let me know. The show is open for bookings.

On Sunday Morning [August 17, 2014 GMT] my segment with Reverend George will air on BBC One, so we’ll see what a million British people think of the debate.

All the best from the religious fringe,

Baba

Here’s a link to the BBC One Sunday Morning Live show, where hopefully you’ll be able to catch the segment featuring Baba and Reverend George Hargreaves either livestreamed or shortly thereafter.

A science movie and a science play

Onto the science movie and the play: David Bruggeman on his Pasco Phronesis blog writes about two upcoming movie biopics featuring Alan Turing and Stephen Hawking respectively, in an Aug. 8, 2014 posting. Having covered the Turing movie here (at length) in a July 22, 2014 posting here’s the new information about the Hawking movie from David’s Aug, 8, 2014 posting,

Alan Turing and Stephen Hawking are noted British scientists, well recognized for their work and for having faced significant challenges in their lives.  While they were in different fields and productive in different parts of the 20th century (Hawking is still with us), their stories will compete in movieplexes (at least in the U.S.) this November.

The Theory of Everything is scheduled for release on November 7 and focuses on the early career and life of Hawking.  He’s portrayed by Eddie Redmayne, and the film is directed by James Marsh.  Marsh has several documentaries to his credit, including the Oscar-winning Man on Wire.  Theory is the third film project on Hawking since 2004, but the first to get much attention outside of the United Kingdom (this might explain why it won’t debut in the U.K. until New Year’s Day).  It premieres at the Toronto International Film Festival next month [Sept. 2014].

David features some trailers for both movies and additional information.

Interestingly the science play focuses on the friendship between a female UK scientist and her former student, Margaret Thatcher (a UK Prime Minister). From an Aug. 13, 2014 Alice Bell posting on the Guardian science blog network (Note: Links have been removed),

Adam Ganz’s new play – The Chemistry Between Them, to be broadcast on Radio 4 this month – explores one of the most intriguing friendships in the history of science and politics: Margaret Thatcher and Dorothy Hodgkin.

As well as winning the Nobel Prize in Chemistry for her pioneering scientific work on the structures of proteins, Hodgkin was a left-wing peace campaigner who was awarded the Soviet equivalent of the Nobel Peace Prize, the Order of Lenin. Hardly Thatcher’s type, you might think. But Hodgkin was Thatcher’s tutor at university, and the relationships between science, politics and women in high office are anything but straightforward.

I spoke to Ganz about his interest in the subject, and started by asking him to tell us more about the play.

… they stayed friends throughout Dorothy’s life. Margaret Thatcher apparently had a photo of Dorothy Hodgkin in Downing Street, and they maintained a kind of warm relationship. The play happens in two timescales – one is a meeting in 1983 in Chequers where Dorothy came to plead with Margaret to take nuclear disarmament more seriously at a time when Cruise missiles and SS20s were being stationed in Europe. In fact I’ve set it – I’m not sure of the exact date – shortly after the Korean airliner was shot down, when the Russians feared Nato were possibly planning a first strike. And that is intercut with the time when Margaret is studying chemistry and looking at her journey; what she learned at Somerville, but especially what she learned from Dorothy.

Here’s a link to the BBC 4 webpage for The Chemistry Between Them. I gather the broadcast will be Weds., Aug. 20, 2014 at 1415 hours GMT.

Chemistry and authentication of a Lawren Harris painting

The final item for this posting concerns Canadian art, chemistry, and the quest to prove the authenticity of a painting. Roberta Staley, editor of Canadian Chemical News (ACCN), has written a concise technical story about David Robertson’s quest to authenticate a painting he purchased some years ago,

Fourteen years ago, David Robertson of Delta, British Columbia was holidaying in Ontario when he stopped at a small antique shop in the community of Bala, two hours north of Toronto in cottage country. An unsigned 1912 oil painting caught his attention. Thinking it evocative of a Group of Seven painting, Robertson paid the asking price of $280 and took it home to hang above his fireplace.

Roberta has very kindly made it available as a PDF: ChemistryNews_Art.Mystery.Group.7. It will also be available online at the Canadian Chemical News website soon. (It’s not in the July/August 2014 issue.)

For anyone who might recognize the topic, I wrote a sprawling five-part series (over 5000 words) on the story starting with part one. Roberta’s piece is 800 words and offers her  account of the tests for both Autumn Harbour and the authentic Harris painting, Hurdy Gurdy. I was able to attend only one of them (Autumn Harbour).

David William Robertson, Autumn Harbour’s owner has recently (I received a notice on Aug. 13, 2014) updated his website with all of the scientific material and points of authentication that he feels prove his case.

Have a very nice weekend!

Wearable solar panels with perovskite

There was a bit of a flutter online in late July 2014 about solar cell research and perovskite, a material that could replace silicon therefore making solar cells more affordable, which hopefully would lead to greater adoption of the technology. Happily, the publishers of the study seem to have reissued their news release (h/t Aug. 11, 2014 news item on Nanwerk).

From the Wiley online press release Nr. 29/2014,

Textile solar cells are an ideal power source for small electronic devices incorporated into clothing. In the journal Angewandte Chemie, Chinese scientists have now introduced novel solar cells in the form of fibers that can be woven into a textile. The flexible, coaxial cells are based on a perovskite material and carbon nanotubes; they stand out due to their excellent energy conversion efficiency of 3.3 % and their low production cost.

The dilemma for solar cells: they are either inexpensive and inefficient, or they have a reasonable efficiency and are very expensive. One solution may come from solar cells made of perovskite materials, which are less expensive than silicon and do not require any expensive additives. Perovskites are materials with a special crystal structure that is like that of perovskite, a calcium titanate. These structures are often semiconductors and absorb light relatively efficiently. Most importantly, they can move electrons excited by light for long distances within the crystal lattice before they return to their energetic ground state and take up a solid position – a property that is very important in solar cells.

A team led by Hisheng Peng at Fudan University in Shanghai has now developed perovskite solar cells in the form of flexible fibers that can be woven into electronic textiles. Their production process is relatively simple and inexpensive because it uses a solution-based process to build up the layers.

The anode is a fine stainless steel wire coated with a compact n-semiconducting titanium dioxide layer. A layer of porous nanocrystalline titanium dioxide is deposited on top of this. This provides a large surface area for the subsequent deposition of the perovskite material CH3NH3PbI3. This is followed by a layer made of a special organic material. Finally a transparent layer of aligned carbon nanotubes is continuously wound over the whole thing to act as the cathode. The resulting fiber is so fine and flexible that it can be woven into textiles.

The perovskite layer absorbs light, that excites electrons and sets them free, causing a charge separation between the electrons and the formally positively charged “holes” The electrons enter the conducting band of the compact titanium dioxide layer and move to the anode. The “holes” are captured by the organic layer. The large surface area and the high electrical conductivity of the carbon nanotube cathode aid in the rapid conduction of the charges with high photoelectric currents. The fiber solar cell can attain an energy conversion efficiency of 3.3 %, exceeding that of all previous coaxial fiber solar cells made with either dyes or polymers.

Here’s an image used in the press release illustrating the new fiber,

[downloaded from http://www.wiley-vch.de/vch/journals/2002/press/201429press.pdf]

[downloaded from http://www.wiley-vch.de/vch/journals/2002/press/201429press.pdf]

Here’s a link to and a citation for the paper,

Integrating Perovskite Solar Cells into a Flexible Fiber by Longbin Qiu, Jue Deng, Xin Lu, Zhibin Yang, and Prof. Huisheng Peng. Angewandte Chemie International Edition DOI: 10.1002/anie.201404973 Article first published online: 22 JUL 2014

© 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

I found a second item about perovskite and solar cells in a May 16, 2014 article by Vicki Marshall for Chemistry World which discussed some research in the UK (Note: Links have been removed),

A lead-free and non-toxic alternative to current perovskite solar-cell technology has been reported by researchers in the UK: tin halide perovskite solar cells. They are also cheaper to manufacture than the silicon solar cells currently dominating the market.

Nakita Noel, part of Henry Snaith’s research team at the University of Oxford, describes how perovskite materials have caused a bit of a whirlwind since they came out in 2009: ‘Everybody that’s working in the solar community is looking to beat silicon.’ Despite the high efficiency of conventional crystalline silicon solar cells (around 20%), high production and installation costs decrease their economic feasibility and widespread use.

The challenge to find a cheaper alternative led to the development of perovskite-based solar cells, as organic–inorganic metal trihalide perovskites have both abundant and cheap starting materials. However, the presence of lead in some semiconductors could create toxicology issues in the future. As Noel puts it ‘every conference you present at somebody is bound to put up their hand and ask “What about the lead – isn’t this toxic?”’

Brian Hardin, co-founder of PLANT PV, US, and an expert in new materials for photovoltaic cells, says the study ‘should be considered a seminal work on alternative perovskites and is extremely valuable to the field as they look to better understand how changes in chemistry affect solar cell performance and stability.’

Here’s a link to and a citation for the UK researchers’ paper,

Lead-free organic–inorganic tin halide perovskites for photovoltaic applications by Nakita K. Noel, Samuel D. Stranks, Antonio Abate, Christian Wehrenfennig, Simone Guarnera, Amir-Abbas Haghighirad, Aditya Sadhana, Giles E. Eperon, Sandeep K. Pathak, Michael B. Johnston, Annamaria Petrozza, Laura M. Herza, and Henry J. Snaith. Energy Environ. Sci., 2014, Advance Article DOI: 10.1039/C4EE01076K First published online 01 May 2014

This article was open access until June 27, 2014 but now it is behind a paywall.

I notice there’s no mention of lead in the materials describing the research paper from the Chinese scientists. Perhaps they were working with lead-free materials.

Metaphors in a brief overview of the nanomedicine scene circa August 2014

An Aug. 1, 2014 article by Guizhi Zhu (University of Florida), Lei Mei ((Hunan University; China), and Weihong Tan (University of Florida) for The Scientist provides an overview of the latest and greatest regarding nanomedicine while underscoring the persistence of certain medical metaphors. This overview features a prediction and a relatively benign (pun intended) metaphor,

Both the academic community and the pharmaceutical industry are making increasing investments of time and money in nanotherapeutics. Nearly 50 biomedical products incorporating nanoparticles are already on the market, and many more are moving through the pipeline, with dozens in Phase 2 or Phase 3 clinical trials. Drugmakers are well on their way to realizing the prediction of Christopher Guiffre, chief business officer at the Cambridge, Massachusetts–based nanotherapeutics company Cerulean Pharma, who last November forecast, “Five years from now every pharma will have a nano program.”

Technologies that enable improved cancer detection are constantly racing against the diseases they aim to diagnose, and when survival depends on early intervention, losing this race can be fatal. [emphasis mine] While detecting cancer biomarkers is the key to early diagnosis, the number of bona fide biomarkers that reliably reveal the presence of cancerous cells is low. To overcome this challenge, researchers are developing functional nanomaterials for more sensitive detection of intracellular metabolites, tumor cell–membrane proteins, and even cancer cells that are circulating in the bloodstream. (See “Fighting Cancer with Nanomedicine,” The Scientist, April 2014.)

So, the first metaphor ‘racing’ gives the reader a sense of urgency, the next ones, including “fighting cancer’, provoke a somewhat different state of mind,

Eye on the target

The prototype of targeted drug delivery can be traced back to the concept of a “magic bullet,” proposed by chemotherapy pioneer and 1908 Nobel laureate Paul Ehrlich. [emphasis mine] E[hrlich envisioned a drug that could selectively target a disease-causing organism or diseased cells, leaving healthy tissue unharmed. A century later, researchers are developing many types of nanoscale “magic bullets” that can specifically deliver drugs into target cells or tissues.

It would seem we might be in a state of war as you 'fight cancer' with your 'eyes on the target' as you 'shoot magic bullets' in time to celebrate the 100th anniversary of the start to World War I.

Kostas Kostarelos wrote a Nov. 29, 2013 posting for the Guardian Science Blogs where he (professor of nanomedicine at the University of Manchester and director of the university's Nanomedicine Lab) discussed war metaphors in medicine and possible unintended consequences (Note: A link has been removed). Here's his discussion about the metaphors,

Almost every night I have watched the news these past few months my senses have been assaulted by unpleasant, at times distressing, images of war: missiles, killings and chemical bombs in Syria, Kenya, the USA. I wake up the next morning, trying to forget what I watched the night before, and going to work with our researchers to develop the next potential high-tech cure for cancer, thinking: "does what we do matter at all … ?"

So I was intrigued by an article that will be published in one of the scientific journals in our field entitled: "Nanomedicine metaphors: from war to care". The next lab meeting we had was very awkward, because I was constantly thinking that indeed a lot of the words we were using to communicate our science were directly imported from the language of war. Targeting, stealth nanoparticle, smart bomb, elimination, triggered release, cell death. I struggled to find alternative language.

...

... Hollywood analogies and simplistic interpretations about "good" and "bad" may be inaccurate, but they do seem appropriate and convincing.

I must say, however, that even in pathology, modern medicine increasingly considers the disease to be part of our body, often leading to successful treatment not by "eradication" and "elimination" but by holistic management of a chronic condition. The case of HIV therapeutics is perhaps the brightest example of such revisionist thinking, which has transformed the disease from a "death sentence" in the early years after its discovery to a nonlethal chronic infection today.

Kostarelos then contrasts the less warlike 'modern medicine' metaphors with nanomedicine,

In nanomedicine, which is the application of nanotechnologies and nanomaterials to design medical treatments, the war imagery is even more prevalent. Two of the most clinically successful and intensively studied technologies that operate at the nanoscale are "stealth" and "targeted" medicines. "Stealth" refers to a hydrophilic (water-loving) shield built around a molecule or nanoparticle, made from polymers, that minimises its recognition by the body's defence mechanisms. "Targeting" refers to the specific binding of certain molecules (such as antibodies, peptides and others) to receptors (or other proteins) present only at the surface of diseased cells. The literature in nanomedicine is abundant with both "stealthing", "targeting" and combinations thereof.

Kostarelos then asks this question,

The question I keep asking myself since I read the article about war metaphors in nanomedicine has been whether we are using terminology in a simplistic, single-minded manner that could stifle creative and out-of-the-box thinking.

Intriguing unintended consequences, yes?

Getting back to The Scientist article, which I found quite informative and interesting, its 'war metaphors' seem to extend even to some of the artwork accompanying the article,

[downloaded from http://www.the-scientist.com/?articles.view/articleNo/40598/title/Nanomedicine/]

[downloaded from http://www.the-scientist.com/?articles.view/articleNo/40598/title/Nanomedicine/]

Is that a capsule or a bullet? Regardless, this * article provides a good overview of the research.

* The word ‘a’ was removed on Aug. 8, 2014.

Newcastle University (UK) has a PhD Studentship in Synthetic Biology and Nanotechnology available

Open to UK, European Union, and international students, the studentship deadline for applying is Aug. 18, 2014. Here’s more from the Newcastle University notice on the jobs.ac.uk website (Note: Links have been removed),

PhD Studentship in Synthetic Biology and Nanotechnology – Towards Algorithmic Living Manufacturing (TALIsMAN)

Value, Duration and Start Date of the Award
The Doctoral Training Award is for £20,000 per annum. This award covers fees and a contribution to an annual stipend (living expenses).

Three year PhD

Start date: 14 September 2014

Sponsor
Science Agriculture and Engineering Faculty Doctoral Training Awards

Project Description
The discipline of Synthetic Biology (SB), considers the cell to be a machine that can be built -from parts- in a manner similar to, e.g., electronic circuits, airplanes, etc. SB has sought to co-opt cells for nano-computation and nano-manufacturing purposes. During this scholarship programme of doctoral studies the student will pursue investigations at the interface of computing science (biodesign & biomodeling), chemical sciences (nanoparticle delivery systems), microbiology (bacterial genetic engineering) and nanoscience (DNA origami).

Name of the Supervisors
Professor Natalio Krasnogor (Lead Supervisor), School of Computing Science

Dr David Fulton, School of Chemistry

Dr Chien-Yi Chang, Centre for Bacterial Cell Biology

Person Specification and Eligibility Criteria
You must have an MSc in synthetic biology, microbiology, organic chemistry or computing science. You also should have demonstrable independent research skills, e.g. having completed a successful MSc dissertation or having a publication in a recognised peer reviewed conference or, ideally, journal. The candidate must have substantial laboratory experience and excellent programming and numeracy skills.

This award is available to UK/EU and International candidates. If English is not your first language, you must have IELTS 6.5.

Closing Date for Applications
Applications will be considered until Monday 18 August 2014. However, awards may be made to successful applicants before this date and early application is recommended.

So according to the line above, it’s better to apply sooner rather than later. Good luck!

Gold on the brain, a possible nanoparticle delivery system for drugs

A July 21, 2014 news item on Nanowerk describes special gold nanoparticles that could make drug delivery to cells easier,

A special class of tiny gold particles can easily slip through cell membranes, making them good candidates to deliver drugs directly to target cells.

A new study from MIT materials scientists reveals that these nanoparticles enter cells by taking advantage of a route normally used in vesicle-vesicle fusion, a crucial process that allows signal transmission between neurons.

A July 21, 2014 MIT (Massachusetts Institute of Technology) news release (also on EurekAlert), which originated the news item, provides more details,

The findings suggest possible strategies for designing nanoparticles — made from gold or other materials — that could get into cells even more easily.

“We’ve identified a type of mechanism that might be more prevalent than is currently known,” says Reid Van Lehn, an MIT graduate student in materials science and engineering and one of the paper’s lead authors. “By identifying this pathway for the first time it also suggests not only how to engineer this particular class of nanoparticles, but that this pathway might be active in other systems as well.”

The paper’s other lead author is Maria Ricci of École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland. The research team, led by Alfredo Alexander-Katz, an associate professor of materials science and engineering, and Francesco Stellacci from EPFL, also included scientists from the Carlos Besta Institute of Neurology in Italy and Durham University in the United Kingdom.

Most nanoparticles enter cells through endocytosis, a process that traps the particles in intracellular compartments, which can damage the cell membrane and cause cell contents to leak out. However, in 2008, Stellacci, who was then at MIT, and Darrell Irvine, a professor of materials science and engineering and of biological engineering, found that a special class of gold nanoparticles coated with a mix of molecules could enter cells without any disruption.

“Why this was happening, or how this was happening, was a complete mystery,” Van Lehn says.

Last year, Alexander-Katz, Van Lehn, Stellacci, and others discovered that the particles were somehow fusing with cell membranes and being absorbed into the cells. In their new study, they created detailed atomistic simulations to model how this happens, and performed experiments that confirmed the model’s predictions.

Gold nanoparticles used for drug delivery are usually coated with a thin layer of molecules that help tune their chemical properties. Some of these molecules, or ligands, are negatively charged and hydrophilic, while the rest are hydrophobic. The researchers found that the particles’ ability to enter cells depends on interactions between hydrophobic ligands and lipids found in the cell membrane.

Cell membranes consist of a double layer of phospholipid molecules, which have hydrophobic lipid tails and hydrophilic heads. The lipid tails face in toward each other, while the hydrophilic heads face out.

In their computer simulations, the researchers first created what they call a “perfect bilayer,” in which all of the lipid tails stay in place within the membrane. Under these conditions, the researchers found that the gold nanoparticles could not fuse with the cell membrane.

However, if the model membrane includes a “defect” — an opening through which lipid tails can slip out — nanoparticles begin to enter the membrane. When these lipid protrusions occur, the lipids and particles cling to each other because they are both hydrophobic, and the particles are engulfed by the membrane without damaging it.

In real cell membranes, these protrusions occur randomly, especially near sites where proteins are embedded in the membrane. They also occur more often in curved sections of membrane, because it’s harder for the hydrophilic heads to fully cover a curved area than a flat one, leaving gaps for the lipid tails to protrude.

“It’s a packing problem,” Alexander-Katz says. “There’s open space where tails can come out, and there will be water contact. It just makes it 100 times more probable to have one of these protrusions come out in highly curved regions of the membrane.”

This phenomenon appears to mimic a process that occurs naturally in cells — the fusion of vesicles with the cell membrane. Vesicles are small spheres of membrane-like material that carry cargo such as neurotransmitters or hormones.

The similarity between absorption of vesicles and nanoparticle entry suggests that cells where a lot of vesicle fusion naturally occurs could be good targets for drug delivery by gold nanoparticles. The researchers plan to further analyze how the composition of the membranes and the proteins embedded in them influence the absorption process in different cell types. “We want to really understand all the constraints and determine how we can best design nanoparticles to target particular cell types, or regions of a cell,” Van Lehn says.

Here’s a link to and a citation for the paper,

Lipid tail protrusions mediate the insertion of nanoparticles into model cell membranes by Reid C. Van Lehn, Maria Ricci, Paulo H.J. Silva, Patrizia Andreozzi, Javier Reguera, Kislon Voïtchovsky, Francesco Stellacci, & Alfredo Alexander-Katz. Nature Communications 5, Article number: 4482 doi:10.1038/ncomms5482 Published 21 July 2014

This article is behind a paywall but there is a free preview available via ReadCube Access.

I last featured this multi-country team’s work on gold nanoparticles in an Aug. 23, 2013 posting.

Trapping gases left from nuclear fuels

A July 20, 2014 news item on ScienceDaily provides some insight into recycling nuclear fuel,

When nuclear fuel gets recycled, the process releases radioactive krypton and xenon gases. Naturally occurring uranium in rock contaminates basements with the related gas radon. A new porous material called CC3 effectively traps these gases, and research appearing July 20 in Nature Materials shows how: by breathing enough to let the gases in but not out.

The CC3 material could be helpful in removing unwanted or hazardous radioactive elements from nuclear fuel or air in buildings and also in recycling useful elements from the nuclear fuel cycle. CC3 is much more selective in trapping these gases compared to other experimental materials. Also, CC3 will likely use less energy to recover elements than conventional treatments, according to the authors.

A July 21, 2014 US Department of Energy (DOE) Pacific Northwest National Laboratory (PNNL) news release (also on EurekAlert), which originated the news item despite the difference in dates, provides more details (Note: A link has been removed),

The team made up of scientists at the University of Liverpool in the U.K., the Department of Energy’s Pacific Northwest National Laboratory, Newcastle University in the U.K., and Aix-Marseille Universite in France performed simulations and laboratory experiments to determine how — and how well — CC3 might separate these gases from exhaust or waste.

“Xenon, krypton and radon are noble gases, which are chemically inert. That makes it difficult to find materials that can trap them,” said coauthor Praveen Thallapally of PNNL. “So we were happily surprised at how easily CC3 removed them from the gas stream.”

Noble gases are rare in the atmosphere but some such as radon come in radioactive forms and can contribute to cancer. Others such as xenon are useful industrial gases in commercial lighting, medical imaging and anesthesia.

The conventional way to remove xenon from the air or recover it from nuclear fuel involves cooling the air far below where water freezes. Such cryogenic separations are energy intensive and expensive. Researchers have been exploring materials called metal-organic frameworks, also known as MOFs, that could potentially trap xenon and krypton without having to use cryogenics. Although a leading MOF could remove xenon at very low concentrations and at ambient temperatures admirably, researchers wanted to find a material that performed better.

Thallapally’s collaborator Andrew Cooper at the University of Liverpool and others had been researching materials called porous organic cages, whose molecular structures are made up of repeating units that form 3-D cages. Cages built from a molecule called CC3 are the right size to hold about three atoms of xenon, krypton or radon.

To test whether CC3 might be useful here, the team simulated on a computer CC3 interacting with atoms of xenon and other noble gases. The molecular structure of CC3 naturally expands and contracts. The researchers found this breathing created a hole in the cage that grew to 4.5 angstroms wide and shrunk to 3.6 angstroms. One atom of xenon is 4.1 angstroms wide, suggesting it could fit within the window if the cage opens long enough. (Krypton and radon are 3.69 angstroms and 4.17 angstroms wide, respectively, and it takes 10 million angstroms to span a millimeter.)

The computer simulations revealed that CC3 opens its windows big enough for xenon about 7 percent of the time, but that is enough for xenon to hop in. In addition, xenon has a higher likelihood of hopping in than hopping out, essentially trapping the noble gas inside.

The team then tested how well CC3 could pull low concentrations of xenon and krypton out of air, a mix of gases that included oxygen, argon, carbon dioxide and nitrogen. With xenon at 400 parts per million and krypton at 40 parts per million, the researchers sent the mix through a sample of CC3 and measured how long it took for the gases to come out the other side.

Oxygen, nitrogen, argon and carbon dioxide — abundant components of air — traveled through the CC3 and continued to be measured for the experiment’s full 45 minute span. Xenon however stayed within the CC3 for 15 minutes, showing that CC3 could separate xenon from air.

In addition, CC3 trapped twice as much xenon as the leading MOF material. It also caught xenon 20 times more often than it caught krypton, a characteristic known as selectivity. The leading MOF only preferred xenon 7 times as much. These experiments indicated improved performance in two important characteristics of such a material, capacity and selectivity.

“We know that CC3 does this but we’re not sure why. Once we understand why CC3 traps the noble gases so easily, we can improve on it,” said Thallapally.

To explore whether MOFs and porous organic cages offer economic advantages, the researchers estimated the cost compared to cryogenic separations and determined they would likely be less expensive.

“Because these materials function well at ambient or close to ambient temperatures, the processes based on them are less energy intensive to use,” said PNNL’s Denis Strachan.

The material might also find use in pharmaceuticals. Most molecules come in right- and left-handed forms and often only one form works in people. In additional experiments, Cooper and colleagues in the U.K. tested CC3′s ability to distinguish and separate left- and right-handed versions of an alcohol. After separating left- and right-handed forms of CC3, the team showed in biochemical experiments that each form selectively trapped only one form of the alcohol.

The researchers have provided an image illustrating a CC3 cage,

Breathing room: In this computer simulation, light and dark purple highlight the cavities within the 3D pore structure of CC3. Courtesy:  PNNL

Breathing room: In this computer simulation, light and dark purple highlight the cavities within the 3D pore structure of CC3. Courtesy: PNNL

Here’s a link to and a citation for the paper,

Separation of rare gases and chiral molecules by selective binding in porous organic cages by Linjiang Chen, Paul S. Reiss, Samantha Y. Chong, Daniel Holden, Kim E. Jelfs, Tom Hasell, Marc A. Little, Adam Kewley, Michael E. Briggs, Andrew Stephenson, K. Mark Thomas, Jayne A. Armstrong, Jon Bell, Jose Busto, Raymond Noel, Jian Liu, Denis M. Strachan, Praveen K. Thallapally, & Andrew I. Cooper. Nature Material (2014) doi:10.1038/nmat4035 Published online 20 July 2014

This paper is behind a paywall.

New ways to think about water

This post features two items about water both of which suggest we should reconsider our ideas about it. This first item concerns hydrogen bonds and coordinated vibrations. From a July 16 2014 news item on Azonano,

Using a newly developed, ultrafast femtosecond infrared light source, chemists at the University of Chicago have been able to directly visualize the coordinated vibrations between hydrogen-bonded molecules — the first time this sort of chemical interaction, which is found in nature everywhere at the molecular level, has been directly visualized. They describe their experimental techniques and observations in The Journal of Chemical Physics, from AIP [American Institute of Physics] Publishing.

“These two-dimensional infrared spectroscopy techniques provide a new avenue to directly visualize both hydrogen bond partners,” said Andrei Tokmakoff, the lab’s primary investigator. “They have the spectral content and bandwidth to really interrogate huge parts of the vibrational spectrum of molecules. It’s opened up the ability to look at how very different types of vibrations on different molecules interact with one another.”

A July 15, 2014 AIP news release by John Arnst (also on EurekAlert), which originated the news item, provides more detail,

Tokmakoff and his colleagues sought to use two-dimensional infrared spectroscopy to directly characterize structural parameters such as intermolecular distances and hydrogen-bonding configurations, as this information can be encoded in intermolecular cross-peaks that spectroscopy detects between solute-solvent vibrations.

“You pluck on the bonds of one molecule and watch how it influences the other,” Tokmakoff said. “In our experiment, you’re basically plucking on both because they’re so strongly bound.”

Hydrogen bonds are typically perceived as the attractive force between the slightly negative and slightly positive ends of neutrally-charged molecules, such as water. While water stands apart with its unique polar properties, hydrogen bonds can form between a wide range of molecules containing electronegative atoms and range from weakly polar to nearly covalent in strength. Hydrogen bonding plays a key role in the action of large, biologically-relevant molecules and is often an important element in the discovery of new pharmaceuticals.

For their initial visualizations, Tokmakoff’s group used N-methylacetamide, a molecule called a peptide that forms medium-strength hydrogen-bonded dimers in organic solution due to its polar nitrogen-hydrogen and carbon-oxygen tails. By using a targeted three-pulse sequence of mid-infrared light and apparatus described in their article, Tokmakoff’s group was able to render the vibrational patterns of the two peptide units.

“All of the internal vibrations of hydrogen bonded molecules that we look at become intertwined, inextricably; you can’t think of them as just a simple sum of two parts,” Tokmakoff said.

More research is being planned while Tokmakoff suggests that water must be rethought from an atomistic perspective (from the news release),

Future work in Tokmakoff’s group involves visualizing the dynamics and structure of water around biological molecules such as proteins and DNA.

“You can’t just think of the water as sort of an amorphous solvent, you really have to at least on some level think of it atomistically and treat it that way,” Tokmakoff said. “And if you believe that, it has huge consequences all over the place, particularly in biology, where so much computational biology ignores the fact that water has real structure and real quantum mechanical properties of its own.”

The researchers have provided an illustration of hydrogen’s vibrating bonds,

The hydrogen-bonding interaction causes the atoms on each individual N-methylacetamide molecule to vibrate in unison. CREDIT: L. De Marco/UChicago

The hydrogen-bonding interaction causes the atoms on each individual N-methylacetamide molecule to vibrate in unison.
CREDIT: L. De Marco/UChicago

Here’s a link to and a citation for the paper,

Direct observation of intermolecular interactions mediated by hydrogen bonding by Luigi De Marco, Martin Thämer, Mike Reppert, and Andrei Tokmakoff. J. Chem. Phys. 141, 034502 (2014); http://dx.doi.org/10.1063/1.4885145

This paper is open access. (I was able to view the entire HTML version.)

A July 15, 2014 University of Southampton press release on EurekAlert offers another surprise about water,

University of Southampton researchers have found that rainwater can penetrate below the Earth’s fractured upper crust, which could have major implications for our understanding of earthquakes and the generation of valuable mineral deposits.

The reason that water’s ability to penetrate below the earth’s upper crust is a surprise (from the news release),

It had been thought that surface water could not penetrate the ductile crust – where temperatures of more than 300°C and high pressures cause rocks to flex and flow rather than fracture – but researchers, led by Southampton’s Dr Catriona Menzies, have now found fluids derived from rainwater at these levels.

The news release also covers the implications of this finding,

Fluids in the Earth’s crust can weaken rocks and may help to initiate earthquakes along locked fault lines. They also concentrate valuable metals such as gold. The new findings suggest that rainwater may be responsible for controlling these important processes, even deep in the Earth.

Researchers from the University of Southampton, GNS Science (New Zealand), the University of Otago, and the Scottish Universities Environmental Research Centre studied geothermal fluids and mineral veins from the Southern Alps of New Zealand, where the collision of two tectonic plates forces deeper layers of the earth closer to the surface.

The team looked into the origin of the fluids, how hot they were and to what extent they had reacted with rocks deep within the mountain belt.

“When fluids flow through the crust they leave behind deposits of minerals that contain a small amount of water trapped within them,” says Postdoctoral Researcher Catriona, who is based at the National Oceanography Centre. “We have analysed these waters and minerals to identify where the fluids deep in the crust came from.

“Fluids may come from a variety of sources in the crust. In the Southern Alps fluids may flow upwards from deep in the crust, where they are released from hot rocks by metamorphic reactions, or rainwater may flow down from the surface, forced by the high mountains above. We wanted to test the limits of where rainwater may flow in the crust. Although it has been suggested before, our data shows for the first time that rainwater does penetrate into rocks that are too deep and hot to fracture.”

Surface-derived waters reaching such depths are heated to over 400°C and significantly react with crustal rocks. However, through testing the researchers were able to establish the water’s meteoric origin.

Funding for this research, which has been published in Earth and Planetary Science Letters, was provided by the Natural Environmental Research Council (NERC). Catriona and her team are now looking further at the implications of their findings in relation to earthquake cycles as part of the international Deep Fault Drilling Project [DFDP], which aims to drill a hole through the Alpine Fault at a depth of about 1km later this year.

Here’s a link to and a citation for the paper,

Incursion of meteoric waters into the ductile regime in an active orogen by Catriona D. Menzies, Damon A.H. Teagle, Dave Craw, Simon C. Cox, Adrian J. Boyce, Craig D. Barrie, and Stephen Roberts. Earth and Planetary Science Letters Volume 399, 1 August 2014, Pages 1–13 DOI: 10.1016/j.epsl.2014.04.046

Open Access funded by Natural Environment Research Council

This is the first time I’ve seen the funding agency which made the paper’s open access status possible cited.

Darwin’s barnacles become unglued

The world’s strongest glue comes from barnacles and those creatures have something to teach us. From a July 18, 2014 news item on Nanowerk,

Over a 150 years since it was first described by Darwin, scientists are finally uncovering the secrets behind the super strength of barnacle glue.

Still far better than anything we have been able to develop synthetically, barnacle glue – or cement – sticks to any surface, under any conditions.

But exactly how this superglue of superglues works has remained a mystery – until now.

An international team of scientists led by Newcastle University, UK, and funded by the US Office of Naval Research, have shown for the first time that barnacle larvae release an oily droplet to clear the water from surfaces before sticking down using a phosphoprotein adhesive.

A July 18, 2014 Newcastle University (UK) press release, which originated the news item, provides some context and describes the research,

“It’s over 150 years since Darwin first described the cement glands of barnacle larvae and little work has been done since then,” says Dr Aldred, a research associate in the School of Marine Science and Technology at Newcastle University, one of the world’s leading institutions in this field of research.

“We’ve known for a while there are two components to the bioadhesive but until now, it was thought they behaved a bit like some of the synthetic glues – mixing before hardening.  But that still left the question, how does the glue contact the surface in the first place if it is already covered with water?  This is one of the key hurdles to developing glues for underwater applications.

“Advances in imaging techniques, such as 2-photon microscopy, have allowed us to observe the adhesion process and characterise the two components. We now know that these two substances play very different roles – one clearing water from the surface and the other cementing the barnacle down.

“The ocean is a complex mixture of dissolved ions, the pH varies significantly across geographical areas and, obviously, it’s wet.  Yet despite these hostile conditions, barnacle glue is able to withstand the test of time.

“It’s an incredibly clever natural solution to this problem of how to deal with a water barrier on a surface it will change the way we think about developing bio-inspired adhesives that are safe and already optimised to work in conditions similar to those in the human body, as well as marine paints that stop barnacles from sticking.”

Barnacles have two larval stages – the nauplius and the cyprid.  The nauplius, is common to most crustacea and it swims freely once it hatches out of the egg, feeding in the plankton.

The final larval stage, however, is the cyprid, which is unique to barnacles.  It investigates surfaces, selecting one that provides suitable conditions for growth. Once it has decided to attach permanently, the cyprid releases its glue and cements itself to the surface where it will live out the rest of its days.

“The key here is the technology.  With these new tools we are able to study processes in living tissues, as they happen. We can get compositional and molecular information by other methods, but they don’t explain the mechanism.  There’s no substitute for seeing things with your own eyes. ” explains Dr Aldred.

“In the past, the strong lasers used for optically sectioning biological samples have typically killed the samples, but now technology allows us to study life processes exactly as they would happen in nature.”

The press release also notes some possible applications for these research findings (Note: Links have been removed),

Publishing their findings this week in the prestigious academic journal Nature Communications, author Dr Nick Aldred says the findings could pave the way for the development of novel synthetic bioadhesives for use in medical implants and micro-electronics.  The research will also be important in the production of new anti-fouling coatings for ships.

Here’s a link to and a citation for the paper,

Synergistic roles for lipids and proteins in the permanent adhesive of barnacle larvae by Neeraj V. Gohad, Nick Aldred, Christopher M. Hartshorn, Young Jong Lee, Marcus T. Cicerone, Beatriz Orihuela, Anthony S. Clare, Dan Rittschof, & Andrew S. Mount. Nature Communications 5, Article number: 4414 doi:10.1038/ncomms5414 Published 11 July 2014

This paper is behind a paywall although a free preview is available via ReadCube Access.

First ever Nanoscience and Nanotechnology Symposium in English-speaking Caribbean

A July 12, 2014 news item on Nanowerk heralds this new International symposium on nanoscience and nanotechnology,

The ‘International Symposium on Nanoscience and Nanotechnology’ will be hosted at The University of the West Indies (UWI), St. Augustine [in Trinidad and Tobago], from July 15-17, 2014. The symposium, focused on the frontier areas of science, medicine and technology, is the first of its kind in the English-speaking Caribbean and is organised jointly by CARISCIENCE, The UWI and the University of Trinidad and Tobago. The symposium consists of a Public Lecture on Day 1 and Scientific Sessions over Days 2 and 3.

This international symposium is important and ground-breaking since these are widely viewed as revolutionary fields. Nanoscience and nanotechnology are considered to have huge potential to bring benefits to many areas of research and application and are attracting rapidly increasing investments from governments and businesses in many parts of the world.

Despite developments in nanoscience and nanotechnology, the Caribbean as a region has not been involved to the extent that more advanced countries have. As such, this symposium aims to provide a stronger focus on the impact and implications of developments in nanoscience/nanotechnology for stakeholders within the Caribbean region, including researchers, academics, university students, government and policy makers, industry partners and the wider public. The symposium will explore various topics under the following themes:

Nanotechnology for Sustainable Energy and Industrial Applications
Nanotechnology for Electronic Device and Sensor Applications
Nanotechnology in Biology, Medicine and Pharmaceuticals
Nanoscale Synthesis, Nanofabrication and Characterization

A July 11, 2014 UWI news release, which originated the news item, provides details about the speakers and more,

An impressive line-up of leading, globally recognised experts from world-class international and regional institutes awaits, including the Public Lecture titled “Science and the Elements of Daily Life,” to be delivered by world-renowned scientist, Professor Anthony K. Cheetham FRS, University of Cambridge, Vice President and Treasurer of The Royal Society. Additionally, the Keynote Address at the Opening Ceremony will be delivered by The Right Honourable Keith Mitchell, Prime Minister of Grenada, with responsibility for Science and Technology in CARICOM.

Speakers at the scientific sessions include Professor Fidel Castro Díaz-Balart (Scientific Advisor to the President of the Republic of Cuba and Vice President of The Academy of Science, Cuba); Professor Frank Gu (University of Waterloo, Canada); Professor Christopher Backhouse (former Director of the Waterloo Institute of Nanotechnology, University of Waterloo, Canada); Professor G. U. Kulkarni (JNCASR, India) and Professor Masami Okamoto (Toyota Technology Institute, Japan).

Students, teachers, academics and the wider public, are all invited and encouraged to attend and use this unique opportunity to engage these leading scientists.

The free Public Lecture is scheduled for Tuesday July 15, 2014, from 5pm-7.30pm, at the Daaga Auditorium, The UWI, St. Augustine Campus. [emphasis mine] The Scientific Sessions take place on Wednesday and Thursday July 16 and 17, 2014, from 8.30am-5pm, at Lecture Theatre A1, UWI Teaching and Learning Complex, Circular Road, St. Augustine. There will also be a small Poster Session to highlight some research done in the areas of Nanoscience and nanotechnology in the Caribbean.

All attendees (to the scientific sessions) must complete and send registration forms to the email address [email protected] by Sunday, July 13, 2014. Registration forms may be downloaded at the Campus Events Calendar entry by visiting www.sta.uwi.edu/news/ecalendar.

A registration fee must be paid in cash at the registration desk on Wednesday July 16, 2014, Day 2, at the start of the scientific sessions.

  • Academic and non-academic:  TT$ 600
  • Graduate student: TT$ 150
  • Undergraduate student: no cost

For further information on the symposium, please visit the Campus Events Calendar at www.sta.uwi.edu/news/ecalendar

I wish them all the best. They seem (judging by the institutions represented) to have attracted a stellar roster of speakers.