From plants to antimicrobial materials: when nature gives you a starting point

Plants can’t move away from bacteria or infections. Instead, over millions of years, they’ve developed their own chemical defenses to survive.

That’s where my PhD research begins.

My work focuses on antimicrobial materials: materials that can help stop bacteria from growing. These materials are designed to prevent or reduce the growth of microorganisms such as bacteria, fungi and sometimes viruses. They can either kill microbes directly or stop them from multiplying on a surface.

Why is this important?

Antibiotic resistance is becoming one of the biggest global health challenges. More and more bacteria are becoming resistant to commonly used antibiotics, which means that infections that were once easy to treat are becoming harder and sometimes even impossible to cure [1]. This problem affects hospitals, communities and healthcare systems around the world.

For this reason, researchers are not only searching for new antibiotics, but also for new ways to prevent bacteria from spreading in the first place. Prevention is a key strategy. If we can reduce bacterial growth on surfaces, medical devices or wound dressings, we may also reduce the number of infections and the need for antibiotic treatments.

One promising idea is to create materials that are naturally antimicrobial.

Some plant-based molecules already have antimicrobial properties. Compounds such as eugenol, found in cloves, and thymol, found in thyme, can damage bacterial cells and interfere with their normal functions [2], [3]. These molecules can affect the bacterial membrane, disturb cell metabolism and make it more difficult for bacteria to survive. In other words, nature has already done part of the work for us.

Plants produce many of these compounds as a defense mechanism against microorganisms, insects and environmental stress. This makes them very interesting for scientists because they are naturally active and often come from renewable sources. Using molecules inspired by nature can also help us develop more sustainable materials compared to relying only on synthetic antimicrobial chemicals.

However, the challenge is that these molecules are not always very practical on their own. They can be unstable, evaporate easily, dissolve poorly in water or lose their antimicrobial effect quickly. Some of these molecules are also difficult to apply directly to a surface because they may not stay in place for long enough.

This is where chemistry becomes useful.

Instead of using the molecules directly, I modify them so they can be incorporated into polymers. Polymers are large molecules made of repeating units and they can form plastics, coatings, gels, films or fibres. By connecting natural antimicrobial compounds to polymer structures, it is possible to create bigger, more stable materials that can actually be used in real applications.

Once inside a material, these natural compounds can provide longer-lasting antimicrobial activity. The polymer can protect the active molecule, control how it is released or keep it attached to a surface. This makes the antimicrobial effect more durable and useful in real-world conditions.

Depending on how the material is designed, it can work in different ways. It can damage bacterial membranes when bacteria touch the surface. It can slowly release antimicrobial compounds over time. Or it can generate reactive species under light, which can help kill microorganisms through oxidative damage.

In some cases, combining several of these mechanisms makes the material even more effective. For example, a material could release a natural antimicrobial compound while also having a surface that bacteria cannot easily attach to. This combination can reduce bacterial growth and prevent the formation of biofilms, which are communities of bacteria that are much harder to remove.

These kinds of materials could have many future applications. They could be used in medical surfaces that help reduce hospital-acquired infections, antimicrobial coatings for implants and medical devices, wound dressings that prevent bacterial growth, or packaging materials that help keep food safer for longer.

The idea is simple: instead of constantly relying only on cleaning products or antibiotics, the material itself can help prevent bacterial growth.

What I find most interesting about this research is that it combines inspiration from nature with chemistry and materials science to address a very modern problem. Sometimes innovation does not mean inventing something completely new, but learning how to use what nature has already been developing for millions of years.

Learn more about my project here.

References

[1]        M. Naghavi et al., “Global burden of bacterial antimicrobial resistance 1990–2021: a systematic analysis with forecasts to 2050,” The Lancet, vol. 404, no. 10459, pp. 1199–1226, Sep. 2024, doi: 10.1016/S0140-6736(24)01867-1.

[2]        S. Burt, “Essential oils: their antibacterial properties and potential applications in foods—a review,” Int. J. Food Microbiol., vol. 94, no. 3, pp. 223–253, Aug. 2004, doi: 10.1016/J.IJFOODMICRO.2004.03.022.

[3]        A. Marchese et al., “Antimicrobial activity of eugenol and essential oils containing eugenol: A mechanistic viewpoint,” Crit. Rev. Microbiol., vol. 43, no. 6, pp. 668–689, Nov. 2017, doi: 10.1080/1040841X.2017.1295225.