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We can stop the infection before it even enters our body-if we accurately reproduce the texture of insect wings on the surface and start covering elevator buttons and door handles with materials that kill germs or inhibit their development.
Ten million deaths a year. The figure is incomprehensible, but it is often cited by Gerald Larua-Momyu, a researcher of infectious diseases at Imperial College London (UK).
This will be a sad outcome for our world if all disease-causing microbes develop resistance to antibiotics – the main barrier on which we rely in the fight against disease.
Currently, 700 thousand people per year die from diseases that cannot be treated with medicines. And in the last 10 years, the list of drugs that we can use against harmful bacteria has been shrinking before our eyes.
Meanwhile, other pathogens-fungi, viruses, and parasites – were also developing resistance to drugs, almost as fast as we were developing new ones. This means that the diseases they cause are becoming increasingly difficult to treat.
Warns of Leroy of Momu, “if we do nothing, some 10 million people will die each year.”
He is one of those scientists who are looking for new ways to break down the resistance of microbes. Larua-Momu plans to turn the very surfaces through which microorganisms are transmitted from person to person into antimicrobial weapons.
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“The surface that we touch every day – a potential weapon of transmission of infections,” says Leroy of Momo.
And some bacteria, including E. coli and Staphylococcus aureus, sometimes remain viable on the surfaces of inanimate objects for several months.
And this only underlines the importance of constant disinfection and cleaning of surfaces that we often touch.
Elevator buttons
The use of antimicrobial metals or special coatings in the places that we most often touch will reduce the risk of spreading any infection
Some scientists hope that we can destroy infectious microorganisms even before they enter our body-simply by changing the texture of surfaces or covering these surfaces with a special layer that kills viruses and bacteria more quickly.
Leroy of Momo relies on copper alloys. Copper ions are both antibacterial and antiviral, they are able to destroy more than 99.9% of bacteria in just two hours.
Copper is even more effective than silver, which needs moisture to activate its antimicrobial properties.
“Copper has been used by mankind for three millennia – emphasizes Leroy of Momo. “Even the ancient Greeks made medical instruments and kitchen utensils out of copper.”
Nevertheless, copper is rarely used in medical institutions today. This is an expensive metal, it is more difficult to clean without causing corrosion. And then-not everyone will like the metal toilet seat…
Over time, copper was replaced first by stainless steel, then by light and cheap plastic, which, according to Larua-Momyu, can simply be thrown away after a single use, without worrying about sterilization.
And although it is not possible to cover all the surfaces around with copper, Larua-Momyu believes that to contain the spread of microbes and reduce infection, it will be enough to use this metal in alloys in those “hot spots” that people constantly touch – elevator buttons, door handles, etc.
In addition, copper surfaces can be treated with a laser, creating a rough texture that increases the surface area and thus the number of bacteria that it is able to destroy.
Researchers from Purdue University (Indiana), who developed this technology, found that such a surface can kill even highly concentrated strains of antibiotic-resistant bacteria in just a couple of hours.
And such treatment will be useful not only for door handles, but also, for example, for medical implants when replacing the hip joint, reducing the risk of infection.
There are other suggestions for changing the surface texture.
“Cicada wings have self-cleaning properties,” says Elena Ivanova, a molecular biochemist at Melbourne’s Royal University of Technology (Australia).
Their wings have hydrophobic properties, water droplets simply roll off them, just like from lotus leaves, along with pollutants.
More importantly, she points out, the wings of cicadas are studded with tiny spines that prevent bacterial colonies from forming on the surface.
“This is a unique mechanism created by nature to destroy bacterial cells,” explains Ivanova, who has been developing ways to mimic the cicada wing for almost a decade.
Hospitals are finding it increasingly difficult to keep control of bacteria that have become resistant to antibiotics
Hospitals are finding it increasingly difficult to keep control of bacteria that have become resistant to antibiotics
The saturation, geometric characteristics, as well as the method and materials for the production of such a surface will depend on which microbes are planned to be combated.
According to Ivanova, the complex zigzag texture is particularly effective in water and air filters.
Graphene sheets are very thin, with sharp protrusions that cut through the membrane of bacteria and kill them (although these microscopic razors can also damage human skin).
Ivanova is particularly enthusiastic about the possibility of using titanium and titanium alloys. They can be processed hydrothermally, under the influence of high temperature and pressure, so that a thin sheet of metal will then have sharp protrusions and edges that destroy various types of bacteria.
In addition, titanium dioxide, when exposed to ultraviolet radiation, forms reactive oxygen species, such as peroxides, which inactivate (block) microbes. This is already used, for example, in the coating of braces in dentistry.
“Such surfaces do not require any special treatment,” emphasizes Ivanova.
However, the production of these surfaces will require a high degree of precision, since their elements are smaller than bacteria.
But, according to Vladimir Baulin, a biophysicist from the University of Rovira y Verhili (Spain), such technologies can be used against viruses, including coronavirus.
One possible strategy is to trap virus particles between nanocomponents artificially created on the surface. This will help scientists collect virus particles for research and vaccine development.
Another strategy is to apply a texture to the surface that has sharp protrusions that could physically pierce the outer membrane of the virus cell. Such a surface could be used, for example, in mask filters.
Take tea tree oil, a pungent-smelling component of many beauty products. As Ponce notes, experimental studies have found that tea tree oil aerosol has a strong antiviral effect and is able to block virus samples with an efficiency exceeding 95% – in just 5-15 minutes of exposure.
The cork has proven to be a highly effective antibacterial material against Staphylococcus aureus.
And hop extracts were used to produce a plastic-like coating that prevented certain types of bacteria from growing on surfaces.
Such studies are still only at the experimental stage. In theory, such natural materials could be turned into antimicrobial coatings, but much remains to be learned about the exact amount of the main ingredients and the type of microorganisms that these coatings will target.
Cicada
If we can copy the structural features of cicada wings, this surface will help fight the formation of bacterial colonies.
But in general, the scope of potential applications of antimicrobial surfaces is quite wide. “I think it’s important to emphasize that this is a universal mechanism, and that’s why the range of applications is so wide,” says Baulin.
As she notes, regardless of how good the technology is, you still need to adhere to the basic requirements for medical institutions – qualified personnel, nurses, hygiene, conditions for the prevention and control of infectious diseases, as well as the possibility of vaccination. There are no easy solutions here.
In poor countries, where there is not always reliable access to running water, it is especially difficult to keep clean those surfaces that need to be treated frequently.
There is also a Micro-Shield 360 coating, which is applied to the seats in airliners to avoid the accumulation of bacteria on them.
And although 3D printers rarely work at the nanoscale, some of their models can do it. Someday, it will be possible to print a micro-repellent surface right at home.
In future confrontations with infectious diseases and pandemics, such surfaces can become an important tool. Even today, for the world struggling with the Covid-19 virus, the problem of antimicrobial resistance is unprecedented.
There is also a significant risk of secondary infections that the patient may pick up already in the hospital: as one study showed, 50% of patients who died in a Chinese hospital from Covid-19 were also infected with another pathogen (potentially fatal).
Those infected with the coronavirus are usually given antibiotics . This reinforces concerns about further increasing the resistance of bacteria to the drugs.