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Nanocone film combines bacterial killing with self-release effect
Researchers have developed a transparent and flexible nanocone array film grafted with a thermo-responsive polymer that mechanically kills bacteria and releases their debris on demand. The approach offers a sustainable, antibiotic-free route to antibiofouling coatings for medical, wearable and optical applications.
The growing risk of antibiotic resistance has accelerated the search for surfaces that combat bacterial contamination without relying on biocides. Inspired by the nanopillar structures found on cicada wings, mechanically bactericidal surfaces have shown promise, but their efficiency declines rapidly as killed bacteria accumulate on the nanostructures. A new study addresses this limitation by combining nanostructure-based killing with a thermo-responsive release mechanism.
The researchers grafted poly(N-isopropylacrylamide) (PNIPAAm) onto a transparent and flexible nanocone array film. The polymer exhibits temperature-dependent swelling and deswelling, which was confirmed by in-situ atomic force microscopy. This responsive behaviour enables the controlled detachment of bacterial debris from the nanostructured surface, restoring the bactericidal capability of the film.
Sustainable mechanical bactericidal performance
In colony-forming unit assays, the PNIPAAm-grafted nanocone film achieved a mechanical bactericidal rate of 55 % and a bacterial release efficiency of 98 %. The combination of these two effects allows the surface to maintain its antibacterial activity across repeated use cycles, addressing one of the key sustainability challenges of nature-inspired bactericidal coatings. Importantly, the purely mechanical mechanism does not contribute to the development of antimicrobial resistance.
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Transparency and flexibility for multifunctional applications
The film retained high optical transparency and mechanical flexibility in both air and aqueous environments, broadening its potential application scope. The authors suggest that such coatings could be applied to medical devices, wearable sensors and optical systems where antibiofouling performance must be combined with visual clarity and conformability. The study highlights a route towards next-generation antibacterial coatings that integrate mechanical killing with active self-cleaning functionality.
Source: Kim, H.-K. et al., Mechanically bactericidal and self-releasing transparent nanocone array films for multifunctional antibiofouling surfaces. Progress in Organic Coatings, 110107 (2026).
