Scientists discover the best way to clean nanotubes is to put them in the microwave

Scientists have discovered that despite all the advanced technology that can be found in a nanomaterials lab a humble microwave oven might well be the most useful.

Researchers from Rice University in Houston and Swansea University in the UK have discovered, the residue that remains from the formation of nanotubes is easier to remove if the tubes are put in a standard kitchen microwave first, before a high-temperature chlorine is used to eliminate almost all of the extraneous particles.

“The chlorine method has the advantage of not damaging the nanotubes, unlike other methods,”  said professor Andrew Barron. “Unfortunately, many of the residual catalyst particles are surrounded by a carbon layer that stops the chlorine from reacting, and this is a problem for making high-purity carbon nanotubes.”

Image courtesy of irginia Goméz Jiménez, Swansea University

Image courtesy of irginia Goméz Jiménez, Swansea University

Nanotubes are good for many things, but when used in sensitive practices like drug delivery or for solar panels, they need to be as pristine as possible.

To measure the success of the microwave technique, researchers gathered microscope images and spectroscopy data on batches of single-walled and multiwalled nanotubes before and after microwaving them in a 1,000 watt oven, and again after bathing them in an oxidizing bath of chlorine gas under high heat and pressure.

They found that once the iron particles were exposed to the microwave, it was much easier to get them to react with chlorine.


Although the technique worked well when removing particles on the surface of nanotubes those lodged inside proved harder to eliminate.

However, transmission electron microscope images showed that by exposing the tubes to a microwave  greatly diminished the amount of particles that remained lodged inside the tubes, especially in the single-walled variety.

“We would like to remove all the iron, but for many applications, residue within these tubes is less of an issue than if it were on the surface,” Barron said. “The presence of residual catalyst on the surface of carbon nanotubes can limit their use in biological or medical applications.”

Our current method of producing meat for consumption is unsustainable, but our brightest minds are already inventing alternatives. In the future, meat from an animal may be nothing more than a distant memory

I’m not sure whether it’s the taste or the sight of a burger that’s so appealing; maybe it’s the fulfilment of a raw, carnivorous desire in me or the aesthetic appeal of seeing meat ooze that’s so alluring. I know that what gives meat much of its unique flavour is haem, a compound found in all living cells, including plants. So with that knowledge, it shouldn’t be hard to imagine a future where my favourite burger joint is proud to admit the meat they serve is derived entirely from plants, or where family barbeques are made possible because of meat grown in a lab. But that future seems as far away as humans living on Mars – ok, that might be a bit of an exaggeration.

Meat eating is so ingrained in many peoples’ diets that it’s hard to even consider alternatives. But we need to. Our current method of producing meat is unsustainable, and most of the environmental crises that blight our planet can be linked back to meat eating. I know this, but luckily for me, as a meat eater, so do some of our most innovative and inventive minds. The meat industry is ripe for disruption, but are we ready to adopt science’s best alternatives?

We cannot continue on this path which puts the environment, public health and food security at risk

The evidence to suggest we have to is very convincing. According to the World Wildlife Fund, the meat industry is responsible for 20% of greenhouse gas emissions – which makes it more problematic than transportation. Animals are not just raw materials, they’re living beings, and rearing them for consumption has a massive impact on our environment. Producing 1kg of beef requires 15 times as much land as producing 1kg of cereals, and 70 times as much land as 1kg of vegetables. Making meat also requires supplying animals with vast amounts of food and water: 40% of global grain production is used for animal feed – although in richer countries this increases to around 70% – and water used in livestock production currently accounts for 15% of all irrigated water – this number is expected to increase to 50% by 2025.

Growing animals in the lab

The meat industry is mostly hidden from the public eye; to a large extent we don’t really care where our meat comes from as long as it is readily available and reasonably priced. But the idea of killing billions of animals for their meat might one day seem as crazy as considering the horse as the best mode of transportation – especially since innovators such as biofabrication company Modern Meadow are already proposing a much more humane and evolved method of sourcing meat.

The New York-based company has pioneered using animal cells to grow meat and other products derived from animals, such as leather. This technique has already been used in medicine, where sophisticated body parts have been successfully implanted into patients. Now the company believes this process can be used to drag our environmentally irresponsible, inhumane and inefficient meat industry into the 21st century.

“I’m convinced that in thirty years, when we look back on today and how we slaughter billions of animals to make our hamburgers and handbags, we’ll see this as being wasteful and indeed crazy,” says Modern Meadow CEO Andras Forgacs. “Right now we breed and raise highly complex animals only to create products that are made of relatively simple tissues. What if instead of starting with a complex and sentient animal, we started with what the tissues are made of, the very basic unit of life, the cell?”


Image courtesy of Anton_Ivanov /

The process used by Modern Meadow to culture animal cells takes inspiration from how we currently produce wine, beer or yoghurt, and this method of manufacturing with cell cultures has been used for thousands of years. As Forgacs points out, “a brewery is essentially a bioreactor.”

In order to make the concept of manufacturing cells in a laboratory more palatable to consumers and regulators, Modern Meadow is beginning by engineering leather – the process to make leather is simpler because it mainly uses one cell type. However, the company don’t aim to just reproduce leather; it envisions a future where we improve upon nature and tune leather to make it softer, more durable and more breathable. If this is successful, it may not be long before we see leather being worn by Olympic athletes, Premier League footballers and NBA stars, rather than being the preserve of rockers and motorcycle enthusiasts.

If this kind of transformation is possible then perhaps we will also be able to engineer superior food products. But for now, Forgacs is clear on one thing. “We cannot continue on this path which puts the environment, public health and food security at risk,” he says.

Why wouldn’t you eat a plant-based burger?

If growing meat in a lab is too much like a Frankenstein nightmare for you, then perhaps the idea of creating meat from plants will be less polarising. The likes of Bill Gates, Hong Kong tycoon Li Ka-shing and Google Ventures believe so. They are all investors in Impossible Foods, a company which uses plants to make meats and dairy products that taste, smell and – in the case of burgers – ooze like the real thing.

Image courtesy of Impossible Foods

Image courtesy of Impossible Foods

For humankind to shift to eating plants, regardless of how similar they are in taste to traditional meats, would clearly take a monumental paradigm shift. To many, meat eating is not just about satisfying the biological urge to avoid hunger. It fulfils our primal hunter-gather urges, and the amount of meat a nation consumes is indicative of its wealth. It’s no surprise that when a country such as China moves its citizens out of poverty, meat consumption rises dramatically. Therefore marketing plant-based meats to carnivores and wealthy nations is never going to be easy – but when has a problem like that ever stopped our tech disruptors?

“Plenty of people, regardless of gender, value their health and the health of our planet. Our experience shows that people are happy to embrace plant-based alternatives as long as they are just as satisfying and delicious as animal-derived foods. Our Impossible burger meets that challenge, so we are confident that it will be a tremendous success,” Impossible Foods told Factor.

“The most important thing for us is to produce foods that satisfy, delight and nourish people as well as being better than those derived from animals. You can’t force people to change their eating habits.  You have to give them a better alternative to what they’re eating – and that’s what we’re doing at Impossible Foods.”

Impossible Foods is the brainchild of Patrick O. Brown, MD, PhD, who arrived at the idea while on sabbatical from his position as a professor. When faced with the question of whether we maintain an unsustainable meat industry at the expense of our ecological future, Brown drew on his training and expertise in biochemistry in a bid to make the largest and most positive impact on the world.  He realised there was a better way to make meat – directly from plants – that would taste better and be better for the environment.

You can’t force people to change their eating habits.  You have to give them a better alternative to what they’re eating

While the US will be the first market Impossible Foods caters for, the company says it has received lots of interest from around the world from people who “would gladly give up animal products if there were a tasty and satisfying plant-based alternative”

Given that the company is targeting the American meat eater it is unsurprising that it is starting with a plant-based burger, which along with cowboys and country music is probably the item most synonymous with American culture. However, Impossible Foods say the methods it’s been developing will enable it to reproduce any of the foods that are currently produced using animals, such as steak, bacon, fish, chicken, milk, and cheese. However, whether anyone will feel the same amount of pride at winning a plant-based steak eating contest is yet to be seen.

Changing how we define meat

If left to its own devices the meat industry will continue to plunder the environment to satisfy our demand for meat. Modern Meadow estimates that as the global population rises – and it is expected that some ten billion of us will be roaming the Earth by 2050 – we will need to increase the number of livestock from the 60 billion we maintain today to 100 billion animals.


Clearly that’s unsustainable, and while our efforts to quell production won’t end all our environmental problems – if Americans start eating less beef it’s still unlikely a corn farmer in Iowa will miraculously begin exporting wheat to Africa – this is enough of problem to demand that we begin considering alternatives right now.

It’s difficult to imagine a world where traditional meat is no longer a staple of our diet, but if we have an alternative that looks, smells and tastes the same as real farmed meat and allows Daisy the cow to live a happy and fulfilling life, why wouldn’t we choose that?

Whether you favour plant-based alternatives or laboratory-cultured animal cells, what we consider to be meat is about to change drastically. The meat industry is ripe for disruption, and that process is already underway.