Cell a million

Solar cells were once a bespoke product, reserved for satellites and military use. In 1977 a watt of solar generating capacity cost $77. That has now come down to about 80 cents, and solar power is beginning to compete with the more expensive sort of conventionally generated electricity. If the price came down further, though, solar might really hit the big time—and that is the hope of Henry Snaith, of Oxford University, and his colleagues. As he described recently in Science, Dr Snaith plans to replace silicon, the material used to make most solar cells, with a substance called a perovskite. This, he believes, could cut the cost of a watt of solar generating capacity by three-quarters.

When light falls on a solar cell, it knocks electrons away from the cell’s material and leaves behind empty spaces called holes. Electrons and holes then flow in opposite directions and the result is an electric current. The more electrons and holes there are, and the faster they flow, the bigger the current will be.

Perovskites are substances composed of what are known as cubo-octahedral crystals—in other words, cubes with the corners cut off. They thus have six octagonal faces and eight triangular ones. Perovskite itself is a naturally occurring mineral, calcium titanium oxide, but lots of other elemental combinations adopt the same shape, and tinkering with the mix changes the frequency of the light the crystal absorbs best.

Dr Snaith’s perovskite is a particularly sophisticated one. It has an organic part, made of carbon, hydrogen and nitrogen, and an inorganic part, made of lead, iodine and chlorine. The organic part acts as a dye, absorbing lots of sunlight. The inorganic part helps conduct the electrons thus released.

It is also cheap to make. Purifying silicon requires high (and therefore costly) temperatures. Dr Snaith’s perovskite can be blended at room temperature. Laboratory versions of cells made from it cost about 40 cents per watt (ie, about half the cost of commercial silicon-based solar cells). At an industrial scale, Dr Snaith expects, that will halve again.

There are caveats, of course. The new perovskite is such a recent invention that its durability has not been properly tested. Many otherwise-promising materials fail to survive constant exposure to the sun, a sine qua non of being a solar cell. And the process of converting a laboratory-made cell into a mass-manufactured one is not always straight forward.

If it leaps these hurdles, though, Dr Snaith’s material will be a strong challenger for silicon. As solar power-generation becomes a mainstream technology over the next few years, the once-strange word “perovskite” may enter everyday language.

First published on economist.com.

Precision strike

In the last 100 years antibiotics have saved millions of lives. However, they are indiscriminate weapons: they kill useful bacteria, such as those in the human gut which extract nutrients, as efficiently as they kill the nasty disease-causing sort. Ben Feringa, of the University of Groningen, in the Netherlands, and his colleagues have devised a method to make antibiotics more selective.

As they report in Nature Chemistry, this was achieved by slapping chemical structures called diazo compounds to a class of antibiotic called quinolones, developed to treat urinary tract infections. Different diazo compounds absorb particular wavelengths of light (it is these structures which give dyes their distinctive colour). They then added the mixture to a Petri dish containing the bacterium E. coli, shielded part of the dish and irradiated the uncovered parts with ultraviolet light. Two of the nine compounds they tested worked as hoped: whereas E. coli remained abundant in the covered parts of the Petri dish, the sections exposed to the light were almost entirely cleared of bacteria.

Crucially, in the half hour or so after exposure to the light, the diazo groups lose energy and revert to their original structure. This, in turn, switches the antibiotic off again. That way, when the antibiotic travels to other parts of the body or is excreted, it does so in its inactive form, and thus remains harmless to the friendly bacteria living in the gut. (And beyond: excreted antibiotics that make their way into sewers have been blamed for spurring the development of drug-resistant bacteria in the wild.)

The brief active window does, however, mean that Dr Feringa’s drug would only be useful in fighting localised infections, where a half-hour antibiotic raid is plenty, rather than more general ones which require a sustained onslaught. And though light can, in principle, be delivered deep inside the body using an endoscope (as happens in some cancer treatments), this is finicky and expensive in practice. As a result, light-activated antibiotics would probably be limited to easily accessible infections on the skin (in wounds, for instance) or in the mouth, ears or nose.

At least for now, that is, for Dr Feringa is working on flipping his chemical switch using sources of energy found inside the body, such as heat or certain energy-rich enzymes. If he succeeds, incidents of antibiotic friendly fire may be consigned to the history of antibacterial warfare.

First published on economist.com.

Image credit: Ben Feringa

Sexual strategies: The numbers game

In 1948 Angus John Bateman, an English geneticist, proposed that females invest more in producing and caring for their offspring than males because sperm are cheaper than eggs. Since then, however, many species, in particular egg-laying ones, have been found to violate what became known as Bateman’s principle. Such role reversal has left evolutionary biologists baffled.

Some suggeseted that species in which females lay eggs that are big compared to their bodies may need more time to recover after laying eggs and males perform nest chores to compensate. Others fingered high levels of nest predation, which prompts females to seek more males to mate with, in order to produce more offspring, and leave nests untended; again, males pick up the slack. Neither hypothesis had robust data to back it up.

In 2000 Tamas Szekely, an ornithologist at the University of Bath, put forward an alternative explanation. What determines the role adopted by each sex, Dr Szekely contends, is the ratio of males to females. Typically, females outnumber males. This means a male mates with a female once and goes off in search of another willing partner, leaving the mother to tend the nest. Where the ratio favours males, however, the fathers might care for the young rather than face stiff competition to woo another female. Since the supply of males is low, females compete for them instead.

This idea remained untested, however, mainly because finding reliable data on animal sex ratios is tricky. But Andras Liker, Dr Szekely’s colleague at the University of Sheffield, believes he has found some. For over 20 years researchers around the world have been painstakingly collecting data on waders. Studies by Dr Liker and Dr Szekely showed that the data were good enough to test the sex ratio hypothesis.

As they report in Nature Communications, wading birds’ sex roles are indeed correlated with the sex ratio in 16 of the 18 species they tested. In the five species in which females outnumber males (ruffs and northern lapwings, for instance) mothers care for their brood. In the 11 male-dominant species, including Jesus birds and greater painted snipes, by contrast, it is the fathers who look after the nestlings.

Sex ratios are, of course, in part determined by precisely the sort of behavioural traits Drs Szekely and Liker strive to explain. The reason this does not lead to a chicken-and-egg problem, as it were, is that sex ratios are also a function of other factors, like different mortality rates among adult males and females, themselves the result of things like body size.

Dr Szekely’s idea may help explain why sex-role reversal seldom happens in mammals, where sex ratios tend to favour females (though mammalian males also lack females’ ability to produce milk). It might even, Dr Liker speculates, shed light on other social behaviour in animals, such as homosexual pairing, possibly triggered byof a shortage of available partners of the opposite sex.

First published on economist.com.

Image from Greg Schneider

Drug development: Teaching old pills new tricks

Exploding research costs and falling sales: there seems to be no cure for the pharma industry’s two big afflictions. But it may have found a way to both cut costs and open up new markets: repurposing drugs already approved for treatment of one disease or those that failed to gain approval in the late stages of development. Alas, this is not as easy as it sounds—mostly for legal reasons.

Finding new uses for old or failed drugs is on average 40% cheaper than inventing a new drug from scratch: it allows to skip the early stages of development. Since coming up with a new drug can cost more than $1 billion, such savings are nothing to sneeze at. Repurposing also trims the risk of failure because new drugs hit a dead end mostly during the early stages of development.

In 2007, a report in Nature, a science journal, counted 41 drugs that have found new uses. But there should be many more, experts say. This is why America’s National Institutes of Health, the country’s biggest government agency financing drug research, and the Medical Research Council, its British counterpart, each have launched new grant programmes. Worth $20m and £10m ($15m) respectively, they are meant to allow university researchers analyse failed drugs from big pharma firms such as Pfizer, AstraZeneca and Eli Lilly and see whether they can be repurposed.

Yet such schemes are not enough, as work by Grant Churchill, a researcher at Oxford University, shows. In a recent paper in Nature Communications, another science journal, he describes how he and his colleagues looked for a drug to treat bipolar disorder, which causes uncontrollable mood swings. Instead of developing a new compound, they tested a library of known ones and found that ebselen, a drug first developed to treat stroke, was a candidate. Their claim, based on animal tests, is that ebselen is as good as and much safer than lithium, currently considered the best treatment for bipolar disorder.

But this was where things hit a hurdle that is hard to overcome. Universities do not have the money to further develop promising drug candidates that need to be tested on a large scale. Expensive human trials are usually carried out by pharma firms, which own the patent for a drug and thus can hope to make their money back. But in the case of many repurposed drugs, like ebselen, the patent has expired. Filing for a new one, which is possible, is not of much help: patients could simply buy versions of the drug which are already available from other makers.

One way of solving this problem would be to change the patent system, for instance by extending the length of patent protection, but this could hamper innovation in other ways. A better solution, argues Benjamin Roin, a law professor at Harvard University, is to have regulators grant the drugmaker that has repurposed the drug some exclusivity and thus time to recover research costs: it is rare that a drug is used in the same form and the same dosage for two different diseases; regulators could wait a few years before they allow other firms to offer the drug for the new purpose. If old drugs can learn new tricks, regulators should do so, too.

First published on economist.com.

References:

  1. Singh et al., A safe lithium mimetic for bipolar disorder, Nature Communications2013.
  2. DiMasi et al., The price of innovation: new estimates of drug development costs, Journal of Health Education2003.
  3. Chong & Sullivan, New uses for old drugs, Nature2007.
  4. Roin, Unpatentable Drugs and the Standards of Patentability, Texas Law Review2009.

Image credit: The Economist

Cancer drugs: Refusing to die

Suicide is a part of life. Whenever any of the 100 trillion or so cells that make up the human body malfunction, which happens all the time even in healthy tissue, they are programmed to provoke their own death. The mechanism hinges on a protein called TRAIL, which is produced by the damaged cell and binds to receptors on its surface, causing inflammation. That is a signal for the immune system to sweep in and, through a process called apoptosis, break down the damaged cell and recycle its parts to feed healthy ones. If this self-destruct is subverted, however, the result is a tumour.

When TRAIL’s tumour-suppressing ability was first discovered in 1995 researchers hoped that by discriminating between cancer cells and healthy ones, TRAIL would do away with the debilitating side-effects associated with traditional treatments like radio- and chemotherapy. These are good at destroying tumours but also cause lots of collateral damage. Unfortunately, it turned out that simply injecting a synthetic version of the molecule into the patient’s body provoked only a limited immune response in a handful of cancers.

That, says Joshua Allen from the Pennsylvania State Cancer Institute, was because people assumed that cancer’s subversion of TRAIL consisted merely in halting the molecule’s production within the cell. It turns out, however, that cancerous cells also suppress their TRAIL receptors, so no amount of synthetic TRAIL sloshing about would ever be enough. What you need, Dr Allen reasoned, is something to reboot the TRAIL-producing pathway within cells as well as to unblock their TRAIL receptors. Only then would the immune system be spurred into action.

So he and his colleagues sifted through a library of molecules maintained by America’s National Cancer Institute and found a molecule, called TIC10, whose biochemistry seemed to fit the bill. When enough of these molecules accumulate in a cancer cell, they activate a protein called FOXO3a. This binds to DNA and flips on many biological pathways, including those involved in the TRAIL mechanism that lead to the immune-system alerting inflammation.

As Dr Allen and his colleagues report in Science Translational Medicine, tests in mice with brain tumours confirmed the biochemical hunch. Murine subject given TIC10 lived twice as long as those that received no treatment. The drug also worked for lymphoma, as well as breast, colon and lung cancers. And it did not seem to cause the wasting side-effects typically associated with chemotherapy, suggesting that it can indeed tell cancer cells from healthy ones. As an added bonus, TIC10 is small compared to TRAIL, and cheaper to concoct than the complex protein is.

Last year Dr Allen secured a $1.3m grant from Pennsylvania’s department of health to begin clinical trials. These will be carried out in collaboration with Oncoceutics, a drug company. Nine out of ten promising molecules which work in mice fail in humans, so “Cure for cancer” headlines must wait. If TIC10 does live up to its promise, though, it would make one killer app.

First published on economist.com.

Image from here

A nebulous future

Before Apple launched iCloud in 2011, Steve Jobs allegedly offered to buy Dropbox, a file-sharing service founded in 2007, for $800m. When Dropbox declined, Apple’s late boss disparaged it as a feature, not a company. Soon after, Dropbox raised $250m, putting its value at over $4 billion. Earlier in December Dropbox concluded a promotional campaign that, in just a few weeks, added 2m new users, bringing the total to over 100m, roughly double the number when Jobs made his comment. Consumers, it seems, can’t get enough of the feature.

Dropbox dominates online file-sharing. It boast three times as many users as its closest direct rival, YouSendIt. (Its dominance is even more pronounced when it comes to the volume of data stored.) It eats up 20% of all bandwidth consumed globally by browser-based file-sharing services, against 1% for YouSendIt. Dropbox users save more than 1 billion files every day.

Most of them use the free version of the service. The company makes money by charging for extra storage. Around 4% of users plump for the premium version, though the proportion is growing, according to Arash Ferdowsi, one of the Dropbox’s co-founders. The recent campaign, called Space Race, gave away free space to university students in return for getting their peers to sign up to the service. The hope is that when access to this extra storage runs out after two years, the students, by then freshly-minted professionals, will pay to keep using it.

Dropbox relies on individuals and small firms, for whom its rudimentary security features are good enough; bigger businesses with sensitive information prefer more secure services like Box.net. The advent of competitors in the nebulous form of iCloud, Google’s Drive and Microsoft’s Skydrive, which come pre-installed on their respective makers’ gadgets, does not seem to have dampened enthusiasm for Dropbox. Unlike iCloud, which boasted 190m users by October thanks to its deep integration with Apple’s mobile devices, the service is “platform neutral”—ie, works across different devices and operating systems—and allows easy file-sharing, both useful traits in an increasingly connected world where few people hew devoutly to a single device-maker.

Google and Microsoft clouds emulate Dropbox in these respects. But at a little over 10m users each, they do not yet benefit from from the incumbent’s powerful network effect. If you are sharing files with a dozen other people on Dropbox, a move to Google or Microsoft would require all 12 to move with you.

Dropbox is also striving to make itself the default choice for smartphone users. In 2011 it struck a deal with HTC, a Taiwanese phonemaker, to preinstall Dropbox on its Android devices. In return it gives HTC users 5GB of space for free. HTC has been struggling of late, but Mr Ferdowsi says that his company is in talks with other manufacturers, hoping for similar arrangements.

A bigger long-term worry is the plummeting price of digital storage. With its vast scale, Amazon has driven down costs substantially for the likes of Dropbox, which leases server space from the e-commerce giant. But Google Drive already offers 100GB for $5 a month, half what Dropbox charges for the same amount of storage. And Google can advertise its cloud across its myriad online offerings. Dropbox’s margins are only likely to get wispier in the future.

First published on economist.com.

Image credit: Dropbox

Crowdsourcing ideas

What if you could use a lensless, portable microscope to detect microbes in the air? This did not occur to the designers of the apparatus, which cost hundreds of thousands of pounds to develop but was lying unused in a storeroom at Oxford University. But it did occur to James Dash, a 15-year-old pupil at John Hampden Grammar School in High Wycombe, Buckinghamshire. His winning proposal was one of 51 entries in a competition run by Marblar, a website for crowdsourcing ideas.

CyMap, researchers’ name for the device, is one of countless clever gizmos and techniques mothballed as solutions in search of a problem. An estimated 95% of all technologies coming out of universities never make it to the real world. Marblar, which was launched in September by a bunch of PhD students in Britain, aims to harness the collective imagination to prevent such waste. Other ongoing competitions invite people to come up with uses for a new kind of foam, a probe inspired by a wasp sting or paint-guns to squirt layers of paint just few molecules across.

The original inventors pay a small fee to post a challenge on Marblar’s website, using videos and slideshows to explain in plain English how their technology works. Geeks of all ages then submit their ideas about what it might be used for. Other users rate these before the inventors themselves pick the winner, who typically receives a cash prize of about £500 ($800). In future, says Daniel Perez, one of Marblar’s co-founders, winners may be invited to partner with the inventors and gain a stake in the commercialisation of their joint intellectual effort.

Marblar will not eliminate all waste. Many inventions have straightforward uses, says Lita Nelsen, director of the (rather busy) technology-licensing office of the Massachusetts Institute of Technology, all they need is better marketing. This is something technology transfer officers, often business-minded boffins who are able both to identify prospective licensees and explain the research to a non-scientist, may be better placed to do.

But Marblar is definitely onto something. IP group, a British venture-capital firm that invests in innovations spun out of universities, has ploughed about $600,000 into the start-up. It is already considering creating a company to commercialise a technology to glue strands of DNA without using an enzyme. In another challenge, a PhD student from Cambridge noticed that this is just the sort of thing he needed in his work on novel methods for drug delivery.

First published on economist.com.

Image credit: Marblar