# Mechano-bactericidal activity of cicada wing nanostructures against gram-positive bacteria

## TL;DR

Cicada wings have nanostructures that physically kill gram-positive bacteria by trapping and rupturing them, offering a chemical-free antibacterial strategy.

## Contribution

The study demonstrates a purely physical 'adhere–deform–rupture' mechanism of cicada wing nanostructures against gram-positive bacteria.

## Key findings

- Cicada wing nanopillars show potent bactericidal activity against gram-positive bacteria.
- Bacillus cereus is more efficiently killed than Staphylococcus aureus by the nanostructures.
- The bactericidal effect is purely physical and not due to chemical composition.

## Abstract

Traditional antifouling mechanisms primarily prevent biofouling by inhibiting the initial adhesion of microorganisms to material surfaces. Conversely, the antifouling effect of cicada wings arises from their microstructured or nanostructured surface. These structures trap and rupture adherent microorganisms, which prevent biofilm formation and enable effective antifouling. This study used two typical gram-positive pathogenic strains—the rod-shaped Bacillus cereus and the coccus-shaped Staphylococcus aureus—as model microorganisms. The bactericidal efficacy of the nanopillar array on Pomponia linearis cicada wings against surface-adhered gram-positive bacteria was quantitatively evaluated using live/dead staining. Additionally, the interfacial morphological evolution during bacteria–structure interaction was visualized via scanning electron microscopy/transmission electron microscopy, aiming to elucidate how physical disruption compromises bacterial cellular integrity. The results show that the nanopillar surface exhibits potent bactericidal activity against both gram-positive species, with B. cereus consistently showing higher killing efficiency. This bactericidal effect is not mediated by chemical composition but rather follows a purely physical “adhere–deform–rupture” mechanism. This mechanism has revolutionized the design paradigm of antibiofilm materials, enabling a shift from passive exclusion to an active “capture–and–kill” dual-function strategy.

The colonization and spread of bacteria pose significant biosafety threats to several key industries, including healthcare, food, pharmaceuticals, and biotechnology. To mitigate these risks, the current industry commonly employs intervention measures such as the addition of antibiotics, treatment with chemical disinfectants, and application of antibacterial chemical coatings. However, these chemical sterilization methods may potentially have adverse effects on human health. In contrast, the cicada wing surface, with its natural micro- and nanostructures, exhibits physical antibacterial properties that achieve efficient sterilization while avoiding the health risks associated with chemical agents, thus offering a new approach to safe antibacterial strategies.