NoWe don’t need new antibiotics. No chemical coatings needed. Sometimes you just need to change shape. An Italian study published in Nature Communications opens an innovative path in fight against infections linked to medical devices: exploit the microscopic geometry of surfaces to prevent bacteria from adhering and proliferating. An idea that comes from biophysics, is inspired by the skin of sharks and the wings of dragonflies and could also have an important impact in the battle againstantibiotic resistance.
The problem: biofilms and persistent infections
Catheters, stents, endotracheal tubes and other medical devices save millions of lives every day. But they can also become breeding ground for bacteria. When microorganisms aggregate on a surface, they form a biofilm: a community protected by a matrix that makes them more resistant to antibiotics and immune defenses. The Healthcare-associated infections exceed 50 million cases worldwide each year, and over 60% are attributable to biofilms.
Traditionally, attempts have been made to counteract this phenomenon by intervening on the chemistry of the materials or by applying antimicrobial coatings. The Italian study instead proposes a paradigm shift: moving from chemistry to physics.
From chemistry to physics: the idea that changes perspective
The research was conducted by Roberto Rusconihead of the Applied Physics, Biophysics and Microfluidics unit at the IRCCS Istituto Clinico Humanitas and associate professor of Physics for life sciences, the environment and cultural heritage at Humanitas University, together with Luca Pellegrinopostdoctoral researcher in the same laboratory.
The principle is simple but revolutionary: change the shape of the device surface so that bacteria cannot settle.
«If a surface does not offer a stable support, the bacteria are dragged away by the flow of water, urine or other body fluids in which the devices are immersed, before being able to colonize it – explains Roberto Rusconi -. We’ve found that geometry can make a big difference. Carefully studied microscopic wrinkles and folds create a sort of mechanical barrier that prevents bacteria from attaching. To give an analogy, like a person trying to stand on a curved roof while a strong wind blows, bacteria on wrinkled surfaces are continually pushed and lifted by the flow. The curvatures prevent them from stabilizing, making adhesion and biofilm formation very difficult. It is a completely physical mechanism, based on the dynamics of the fluid and the behavior of microorganisms.”
Roberto Rusconi and Luca Pellegrino (Photo Courtesy Humanitas Press Office)
The inspiration? Sharks and dragonflies
Nature had already found the solution. Sharks have skin covered with microscopic grooves that reduce the accumulation of microorganisms thanks to the flow of water. Dragonflies, on the other hand, have wings with tiny nanometric pillars capable of even physically damaging bacteria. Both structures limit the so-called biofouling, i.e. the adhesion of microorganisms to surfaces.
Starting from these observations, the team created corrugated surfaces in the laboratory using PDMSa silicone polymer similar to that used in many medical devices. The ripples were formed through a physical phenomenon called buckling instability, the same thing that generates wrinkles on the skin when it is compressed.
Reduction of adhesion over 90%
The surfaces were tested in conditions that reproduce the real flow of body fluids, going beyond traditional static experiments. The results were surprising: some wrinkle configurations reduced bacterial adhesion by more than 90 percent, particularly at wrinkles of around five micrometers.
The effect was observed with two bacteria of great clinical relevance: Pseudomonas aeruginosa And Staphylococcus aureusfrequently involved in hospital infections associated with medical devices. By keeping the chemistry of the material unchanged, the researchers demonstrated that the result depends exclusively on the geometry. «Taken together, these data indicate a promising, drug-free strategy to design safer medical devices – explains Luca Pellegrino -. This discovery paves the way for new designs of catheters, stents and implants that can dramatically reduce the risk of infections, avoiding phenomena of resistance to antibiotics”.
A technology observed to the millionth of a millimetre
To precisely verify the shape and height of the ripples, the team used advanced microscopy techniques. Francesco Mantegazza of the University of Milan Bicocca performed the first measurements with Atomic Force Microscopy. Subsequently, the CLEM laboratory of Humanitas Universityled by Edoardo D’Imprimaha combined fluorescence optical microscopy And electron microscopy to obtain images with nanometric resolution.
One millionth of a millimetre: this is the scale at which it was possible to observe the behavior of bacteria and the structure of surfaces.
A new frontier against antibiotic resistance
The corrugated surfaces could represent a durable alternative to traditional antimicrobial coatings, reducing the need for antibiotics and limiting the emergence of resistance.
A strategy that It doesn’t kill the bacteria, but it prevents them from taking root.
