Of all places to have an injection, the eyeball is probably near the bottom of anybody’s list. Yet this is how macular degeneration – the leading cause of sight loss in the developed world – is commonly treated.
Individuals who have macular degeneration will have blurred or no vision in the center of their visual fields (as shown above).
In the UK, nearly 1.5m people are affected by macular disease, according to the Macular Society. In its commonest ‘wet’ form, macular degeneration is caused by the growth of rogue blood vessels at the back of the eye, due to over-production of a protein called vascular endothelial growth factor (VEGF).
The blood vessels leak, causing damage to the central part of the retina – the macula – and a loss of central vision. Regular injections of so-called anti-VEGF drugs help to alleviate the problem.
As well as being time-consuming, these injections can be stressful and upsetting for sufferers, many of whom are elderly. Because the condition is prevalent among older people, it is usually referred to as age-related macular degeneration, or AMD.
However, a number of emerging treatments – including eye drops, inserts and a modified ‘contact lens’ – could spell the end of regular injections, and treat the condition less invasively.
Anatomy of the eye. Video: Handwritten Tutorials
At the same time, emerging stem cell therapy, which has reversed sight loss for two patients with the ‘dry’ form of macular degeneration, could find wider use within a few years.
Nature is providing the inspiration for a range of novel self-repairing materials – by mimicking bone healing to fix ceramics, for instance, or using bacteria to heal a ‘wound’ in an undersea power cable.
Self-healing polymers are already well known. A familiar example is self-healing composite aircraft wings: if a crack appears, microcapsules in the composite matrix rupture, releasing ‘sealant’ into the crack to repair it. Recently, however, researchers have expanded the range of ‘repairable’ substances to include other promising materials – including rubber, ceramics and even electronic circuits.
Paul Race, senior lecturer in biochemistry at Bristol University, UK, heads a multi-disciplinary project to develop new types of self-healing materials. The three-year project, called Manufacturing Immortality, is in partnership with six other UK universities and involves biologists, chemists and engineers. ‘Our aim is to create new materials that can regenerate – or are very difficult to break – by combining biological and non-biological components – such as bacteria with ceramics, glass or electronics,’ says Race, whose own research interests include the stereochemistry of antibiotics, and the activities of enzymes.
The project’s approach is quite different to most polymer-based self-healing technologies, which typically rely on simple hydrogen bonds and reversible covalent bonds. ‘There are limits to the polymer chemistry approach,’ he says. ‘We’re trying to take inspiration from biology, which uses much more elaborate and powerful approaches to achieve more dramatic repair.’
Self-healing rubber links permanent covalent bonds (in red) with reversible hydrogen bonds (green). Image: Peter and Ryan Allen/ Harvard press
As an example, Race refers to what happens when we break or bone or receive a bad cut, which triggers a cascade of events in which the body detects the damage and responds appropriately. The team’s work is aimed at three broad application areas: safety critical systems; energy generation; and consumer electronics.
Images of turtles trapped in plastic packaging or a fish nibbling on microfibres pull on the heartstrings, yet many scientists studying plastics in the oceans remain open-minded on the long-term effects.
While plastics shouldn’t be in our oceans, they say there is still insufficient evidence to determine whether microplastics – the very tiniest plastic particles, usually defined as being less than 1mm in diameter – are actually harmful.
It is estimated that over 1,000 turtles die each year from plastic waste. Image: NOAA Marine Debris Program
On top of this, there is debate over how much plastic is actually in the sea and why so much of it remains hidden from view. Much of the research carried out to date is in its early stages – and has so far produced no definitive answers.
‘My concern is that we have to provide the authorities with good data, so they can make good decisions,’ says Torkel Gissel Nielsen, Technical University of Denmark (DTU). ‘We need strong data – not just emotions.’
Searching the sea
Plastic shopping bags can be degraded into microplastics that litter the oceans. Image: Wikimedia Commons
Gissel Nielsen leads a team of researchers who discovered that levels of microplastics in the Baltic Sea have remained constant over the past three decades, despite rising levels of plastics production and use.
The study – by researchers at DTU Aqua, the University of Copenhagen, Denmark, and Geomar, Germany – analysed levels of microplastics in fish and water samples from the Baltic Sea, taken between 1987 and 2015.
‘The result is surprising,’ says Nielsen. ‘There is the same amount of plastic in both the water and the fish when you go back 30 years.’ He claims that previous studies of microplastics levels were ‘snapshots’, while this is the first time levels have been studied over a longer period.
The UK introduced a ban in January this year of the sale and manufacture of products containing microbeads. Image: MPCA Photos
‘The study raises a number of questions, such as where the plastic has gone,’ he says. ‘Does it sink to the bottom, are there organisms that break it down, or is it carried away by currents? Some is in the sediment, some is in the fish, but we need to find out exactly how much plastic is there.’
In the study, more than 800 historical samples of fish were dissected and researchers found microplastics in around 20% of them. This laborious process involved diluting the stomach contents in order to remove ‘organic’ materials, then checking the filtered contents under a microscope to determine the size and concentration of plastics. It illustrates the difficulty of quantifying plastics in any sample, says Gissel Nielsen.
‘You must remove the biology to get a clear view of the plastics,’ he says.
Just as rivers supply the sea with water, they also act as a source of pollution. Researchers at the Helmholtz Centre for Environmental Research (UFZ), Germany, found that 10 large rivers are responsible for transporting 90% of plastic waste into the sea.
The team collected pre-published data on plastics in rivers and collated it with upstream sites of ‘mismanaged’ plastics waste – municipal waste that is uncollected.
‘The more mismanaged plastic waste there was, the more you found in the river,’ says Christian Schmidt, UFZ. ‘There was an empirical relationship between the two.’
The Yangtze river (pictured in Shanghai, China) is the main polluter of plastic in the ocean in the world. Image: Pedro Szekely/Flickr
Eight of these 10 rivers are in Asia, while the other two are in Africa. All of them flow through areas of high population.
‘Countries like India and China have seen huge economic growth – and now use large amounts of plastic food packaging and bottles – but have limited waste collection systems,’ he says. The data include both microplastic and ‘macro’ plastics – but microplastics data dominate ‘because scientists are more interested in that’, says Schmidt.
Plastic Ocean. Video: United Nations
While it is important to measure how much plastic is in the environment, Schmidt believes that the next step of his research will be more important – understanding the journey the plastics make from the river to the sea.
For all the uncertainty and debate over how much plastic is in the sea – and what harm it can do – one thing is clear. Future research is likely to focus more on the plastics that we can’t see, rather than the items we can.
With an ever-increasing demand for data storage, the race is on to develop new materials that offer greater storage density. Researchers have identified a host of exotic materials that use new ways to pack ‘1’s and ‘0’s into ever-smaller spaces.
And, while many of them are still lab curiosities, they offer the potential to improve data storage density by 100 times or more.
Having a moment
Data storage technology has moved quickly away from floppy disks (pictured) and CD-DOMs. Image: Pexels
The principle behind many storage media is to use magnetic ‘read’ and ‘write’ heads, an idea also exploited by many of these new technologies – albeit on a much smaller scale.
A good example is recent work from Manchester University, UK, where researchers have raised the temperature at which ‘single molecule magnets’ can be magnetised. Single-molecule magnets could have 100 times the data storage density of existing memory devices.
In theory, any molecular entity can be used to store data as reversing its polarity can switch it from a ‘1’ to a ‘0’. In this case, instead of reading and writing areas of a magnetic disk, the researchers have created single molecules that exhibit magnetic ‘hysteresis’ – a prerequisite for data storage.
Researchers discuss the circuit boards in development that negotiate Moore’s Law. Video: Chemistry at The University of Manchester
‘You need a molecule that has its magnetic moment in two directions,’ says Nick Chilton, Ramsay Memorial research fellow in the school of chemistry. ‘To realise this in a single molecule, you need very specific conditions.’
In addition to having a strong magnetic moment, the molecule needs a slow relaxation time – that is, the time it takes for the molecule to ‘flip’ naturally from a ‘1’ to a ‘0’. ‘If this time is effectively indefinite, it would be useful for data storage,’ he says.
The key is that the molecule itself must have a magnetic moment. So, while a bulk substance such as iron oxide is ‘magnetic’, individual iron oxide particles are not.
A binary digit, or bit, is the smallest unit of data in computing. The system is used in nearly all modern computers and technology. Image: Pixabay
Chilton and his colleagues have identified and synthesised a single-molecule magnet – a dysprosium atom, sandwiched between two cyclopentadienyl rings – that can be magnetised at 60K. This is 46K higher than any previous single-molecule magnet – and only 17K below the temperature of liquid nitrogen.
Being able to work with liquid nitrogen – rather than liquid helium – would bring the cost of a storage device down dramatically, says Chilton. To do this, the researchers must now model and make new structures that will work at 77K or higher.
Skyrmions may sound like a new adversary for Doctor Who, but they are actually another swirl-like magnetic entity that could be used to represent a bit of digital data.
Scientists at the Max Born Institute (MBI), Germany – in collaboration with colleagues from Massachusetts Institute of Technology, US – have devised a way to generate skyrmions in a controllable way, by building a ‘racetrack’ nanowire memory device that might in future be incorporated into a conventional memory chip.
‘Skyrmions can be conceived as particles – because that’s how they act,’ says Bastian Pfau, a postdoctoral researcher at MBI, as they are generated using a current pulse.
‘Earlier research put a lot of current pulses through a racetrack and created a skyrmion randomly,’ he says. ‘We’ve created them in a controlled and integrated way: they’re created on the racetrack exactly where you want them.’
This racetrack memory device could be incorporated into standard memory chips, say researchers at the Max Born Institute. Credit: Grafix
In fact, skyrmions can be both created and moved using current pulses – but the pulse for creating them is slightly stronger than the one that moves them. The advantage of using a current pulse is that it requires no moving parts.
The resulting racetrack is a three-layer nanowire about 20nm thick – a structure that will hold around 100 skyrmions along a one-micron length of wire.
While the current research is done ‘in the plane’ with the nanowires held horizontally, Pfau says that in the future, wires could be stacked vertically in an array to boost storage capacity. ‘This would increase the storage density by 100. But this is in the future and nobody has made a strip line that’s vertical yet.’
Could magnetic skyrmions hold the answer to better data storage? Video: Durham University
‘The whole function depends on how you create the multi-layer,’ he says. To stand any chance of being commercialised, which might take six or eight years, Pfau says that new materials will be needed.
However, he is confident this will happen – and that the technology can be merged with ‘conventional’ electronic devices.