Bacteria-banishing bandages

Read on for the story of Dr Xiaogang Qu and his life-changing new designs. All words in bold can be found in the glossary at the end of the story. Questions and resources can also be found after the glossary. Happy reading!

Dr Xiaogang Qu is a chemistry researcher at the Chinese Academy of Sciences. 

There, Xiaogang works with a team of other scientists. Some of them are very knowledgeable about chemistry, while others are biologists who study the human body. Together, this team has worked hard to produce new medicines. They combine their knowledge to produce new ways to help people heal. 

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Working together gets the job done!
It’s important for chemists and biologists to work together in fields such as medicine, because their combined knowledge helps them create better, more effective treatments. 
Biologists know a lot about the human body and how it functions, as well as how other organisms, like bacteria, function. These could cause the illnesses that medicine needs to treat. Chemists, on the other hand, focus on treating the problem – medicinal chemists design drugs and other methods of curing disease. 
The combination of these two fields is called biochemistry. 

There is also a picture to the right, of five scientists. Xiaogang stands in the centre, holding a test-tube. There are two scientists to his left, who are both men in lab coats, and two to his right, a man and a woman in lab coats. They are his research team.

Xiaogang is very interested in helping to protect people after they have been hurt. He knows that sometimes when people get injured, their wounds can be infected and made worse by tiny microorganisms called bacteria

Bacteria are minuscule, far too small for us to see with just our eyes, so how can anyone study them? Luckily, Xiaogang works in a laboratory that has plenty of powerful microscopes. By zooming in on things under the microscope, he can identify the different bacteria that live on or in them. 

A drawing of Xiaogang looking through a microscope, which sits on a table.

There are lots of different types of bacteria. Not all of them cause people harm – in fact, some are helpful! Foods like yoghurt contain friendly bacteria, which help our digestive system work properly. Think that’s weird? What about this – some of the friendly bacteria inside your body has been living inside you ever since you were born! 

We don’t meet the bad kinds of bacteria very often, mostly because we do lots of things to protect ourselves from them. Whenever you wash your hands or clean a surface, you’re getting rid of bacteria.

Plus, your body is working to protect you from them too! You have an immune system, which detects bad bacteria when they enter your body and kills them before they can make you ill. 

A drawing of six different bacteria. They are many different shapes - some long and thing, others round and small. They all have faces. Some look happy, some surprised, while some have evil expressions.

Xiaogang is interested in bad bacteria. He knows that some bad bacteria can sneak past our body’s defences, and make us ill. This is especially easy for them at times when our body is already vulnerable. 

Usually, bacteria can only enter our bodies through openings like our mouths and noses. However, when our skin is broken – for example, when we have a cut – bacteria can enter through this open wound and infect our body.

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Infection? No problem!
Harmful bacteria can be spread in lots of different ways, but luckily our body is always there to protect us from them. 
Our skin is the first line of defence – unless it is cut or damaged, microorganisms can’t get through it to hurt us. 
The areas where your body is open to the air are protected too - tiny hairs in your nose, as well as mucus (which you’ll probably know as snot!), trap bacteria, stopping them from entering your body.
Inside your body, lots of systems are ready and waiting to destroy some meddling microorganisms. Your stomach contains lots of chemicals which can kill any bad bacteria from your food, and in your blood, there are special cells whose entire purpose is to fight off any chemicals or microorganisms that might hurt you. 
Your body is busy keeping you safe at all times, without you even thinking about it. Amazing!
There is also a drawing to the right. It shows an outline of the human body and the organs of the digestive system within it, including the stomach and intestines.

Xiaogang wanted to make sure that bacteria that get into wounds are noticed, so that they can be treated quickly, before the injured person becomes infected. We know from first aid that it’s always best to cover open injuries with a plaster or bandage to keep bacteria out, but what if we could go one step further? What if we could design a plaster that was able to tell uswhether there were any bacteria in the wound? 

As a chemist, Xiaogang doesn’t study bacteria themselves (that’s the biologists’ job!), but he is great at creating solutions to the problems that they create. 

Your body is essentially a massive chemical factory – as are the bodies of all other organisms, including bacteria. By studying the chemicals that bacteria produce, and learning how to respond to them, Xiaogang can work out how to fight what’s harmful, and support what’s good. 

Xiaogang knew that we already have a way of physically keeping bacteria out of wounds – plasters and bandages. He also knew that we have a chemical way of treating bad bacteria that are inside the body – using medicine like antibiotics. We can put on a plaster straight away to keep dirt out, but medicine cannot be given until a person shows signs of infection. However, for a person to know that they are infected, bacteria have to cause quite a lot of harm. By the time people notice, the infection may have become serious.

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What’s the difference? 
Think about what you know about coverings like plasters, and medicines that you take, like antibiotics. What properties do they have? How do they work? What is the outcome of using them? How long do their effects last – and how good are they at their job?
Use the table below to list some of your thoughts, focusing in particular on any similarities and differences. 
Below it, there is a table with two columns. One column is headed 'ANTIBIOTICS', and the other 'PLASTERS AND BANDAGES'. There is lots of space below these headings to list properties. At the bottom of the box, there are some drawings of bandage rolls and pill bottles.

“So”, Xiaogang wondered, “how could we combine a barrier, like a plaster, and a medicine, to make one solution that will make sure that infections are treated quickly?” 

In the lab, he and his team worked hard to design a new material – something that could cover a wound to keep out bacteria, like a plaster, and also detect any harmful bacteria that had already sneaked in. They made sure their new design was easy to carry around, so that people could have them on hand – just like normal plasters! 

Just like any other scientists doing research, Xiaogang’s team made predictions about how each element of the design would work. While they were in the lab, they had to scientifically test their design many different times, changing a small thing each time until it was perfect. By observing the design in action over a period of time, they were able to look for signs that it was working, or identify areas which needed improvement.

A drawing of a clipboard with a piece of paper pinned to it. The paper is titled 'DESIGNS'. Underneath, it says 'predictions' and 'observations'. There are also a few different bandage options shown, that are all different shapes. One has a big tick above it, while the others have crosses.

It was really important that Xiaogang spent lots of time carefully perfecting the design, because the plaster may eventually be used to prevent life-threatening infections. It’s vital that scientists test their work thoroughly and carefully, especially when working on things that can affect people’s health.

It wasn’t safe for Xiaogang to test the new plaster design on humans straightaway, because the team weren’t certain how effective their design would be. So, his first tests were on tomatoes, and then mice. 

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Scientific stars: laboratory animals. 
In medical research, animals like mice are often vitally important, because their systems respond in a similar way to human ones. This means that scientists can see whether their treatments work, without risking harm to humans. Currently, medicines are only tested on humans after they have proved safe and effective in animals. 
Animals being used in research is not something that everyone agrees with, and it should only occur when there is no alternative. Even then, there are lots of rules in place to make sure animals are treated as well as possible. 
There is a drawing of a mouse in a cage to the right. He is sat in a hammock over a bed of straw, and looks to be having a good day.

All the hard work put into testing paid off, and Xiaogang’s team managed to create a material that they were happy with! Through a long process of trial and error, they had managed to create a plaster that was able to detect bacteria in the wound. They called this final design “PBA” – a portable band-aid (a band-aid is the American word for a plaster). 

Xiaogang’s plasters had one important new feature that is crucial to their success – when they detect the bad, infection-causing bacteria, they change colour! These ‘smart band-aids’ are green to begin with, but if they detect an infection, they change to yellow. This alerts the injured person, or their carer, to the problem, before bacteria have a chance to make them ill. 

The plasters are able to identify infections in this way, because chemicals inside them are able to detect the acids that harmful bacteria produce. 

In a similar way to you responding to a fire by pulling an alarm, Xiaogang’s plasters are able to respond to these acids, by producing chemicals that make the plaster change colour. 

Even more impressively, if they detect an infection, the plasters release medicine to treat it, without anyone telling them to do so! That’s like you seeing a fire and instantly having water or a fire blanket handy to put it out quickly and safely, rather than leaving it to get worse while you find help.

If the bad bacteria are particularly nasty, and manage to survive this first wave of medicine, the plasters change colour again – this time to red. Again, this alerts the injured person, making sure that they go to a doctor to get the treatment that they need. Shining light on the bandage can be one way to get rid of these pesky drug-resistant bacteria!

A diagram showing how the bandage reacts to bacteria. It has three parts. In the first part, we see how when the bandage encounters any bacteria, it turns from green to yellow. Then, when only the drug-resistant bacteria remain, it turns to red. 
In the second part, we see that the antibiotics on the bandage kill the bacteria, and this corresponds to the bandage changing colour. When the bandage is red, only antibiotic-resistant bacteria remain, and light is applied to the red bandage to kill them. 
The third part explains the difference between drug-sensitive e-coli, which are killed when the bandage is yellow, and drug-resistant e-coli, which are killed when the bandage is red. There is a text-box below, which reads: 
E-coli is a type of bacteria that can make you very ill. E-coli is often used to test new medicines like this bandage, because scientists already know lots and lots about it, which means they can easily understand how it reacts! They then use the reactions of E-coli to predict how other bacteria might be affected by the treatment. Organisms that are used in this way are called model organisms.

This clever chemistry means that infections can be treated quicker than ever before, and that the effects of bad bacteria are less likely to go unnoticed. What an incredible design!

Soon, Xiaogang hopes that these plasters will be available for more and more people to use. They could be particularly important in countries where medical care is harder to access, or people are often wounded. 

Chemistry is often about tiny substances, but it has a big impact. Though Xiaogang might spend most of his time in the lab with his microscopes, his designs will spread far and wide, helping people wherever they go! 

A drawing of an arm with the bandage applied. It looks like a normal bandage on the outside.

Thank you for reading!

This story was written as part of a Masters in Science Communication project, investigating whether storytelling is an effective way to teach children about science and scientists. As a result, I would really appreciate some feedback, which you can give by answering a short survey. The survey takes less than 5 minutes to complete, and I will use the results to develop even better science stories in the future. To help, just click on the button below.

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Acid – a type of chemical that tastes sour and which, as a liquid, is able to make a special kind of paper called litmus paper change colour from blue to red. 
Antibiotics – the name for medicine that is used to kill or prevent the growth of harmful microorganisms.
Bacteria – microorganisms made up of a single cell. 
Biochemistry – the study of the chemicals and processes that occur in living things. Specifically, they often look at the role that chemicals have in developing and sustaining life.
Digestive system –all the organs that are used to turn food and liquids into fuel for your body, and which eliminate food waste. 
Immune system – all the parts of your body that help fight off sickness, and work together to keep you safe from harmful microorganisms.
Infection – an infection happens when microorganisms that are not usually present in your body are able to enter and multiply, causing disease.
Microorganisms – living things too small to be seen with the naked eye, which are usually seen only through microscopes. Some of the best-known microorganisms are bacteria and viruses.
Microscopes – a special piece of scientific equipment, that is used like a complicated magnifying glass. Lenses within a microscope allow the scientist to ‘zoom in’ on whatever they’re looking at. Microscopes are often used to look at things which may be far too small to be seen with the naked eye – like microorganisms!
Model organism – non-human organisms often used in the lab in science experiments. These are often species which have been widely studied, and which are short-lived and easy to care for. 
Observation – taking notice of something. This can be looking at what something looks like, looking at how it changes, or even just seeing that exists.
Prediction – a statement that someone makes about what they think is going to happen.
Property (properties) – a feature, or characteristic of something. For example, some of the properties of gold are that it is shiny and metallic.
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Hungry for more? 
If you’ve loved hearing about how Xiaogang used chemistry creatively to make new designs, have a think about these questions…
1.	What are bacteria? In what ways are they similar, and different, to the cells of animals like humans? 

2.	 Where do you think the bacteria that we are born with comes from? 

3.	How do you think that Xiaogang managed to make colour-changing bandages? Think about other things that you know change colour – how do they do it, and why might knowing about this be useful to Xiaogang?

4.	Xiaogang’s bandages detected that bacteria were present because of the acids that they produce. What else do you know about acids? Could you name something acidic? Make a list!

5.	Antibiotics are able to find bacteria and kill them in the body. Antibiotics are usually taken by eating or drinking - how do you think they manage to reach bacteria, after you’ve swallowed them?


Xiaogang’s research paper: Sun, Y., Zhao, C., Niu, J., Ren, J., Qu, X. (2020). Colorimetric band-aids for point-of-care sensing and treating bacterial infection. American Chemical Society Central Science. 6: 207-212.

More information about Xiaogang’s work:

Article: Scientists design bandages that can ‘sense and treat bacterial infections’

Article: Color-changing bandages sense and treat bacterial infections

More information on bacteria and infections:

Public Health England e-Bug resource

BBC Bitesize: Microorganisms What are germs?

More information about animal testing:

Planet Science: The Animal Testing Debate


The research was produced not just by Dr Xiaogang Qu, but also by the other members of their research team: Yuhuan Sun, Chuanqi Zhao, Jingsheng Niu, and Jinsong Ren. They too deserve credit for this discovery – good science is often best done as a team. 

This story would not be nearly so good without its illustrations by the wonderful Alice Chen, and the advice and support of Dr. Nicola Hemmings. Thank you!

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