Antifungal versus antibacterial defence of insect wings
Ivanova, Elena P; Linklater, Denver P; Aburto-Medina, Arturo; Le, Phuc; Baulin, Vladimir A; Khuong Duy Nguyen, Huu; Curtain, Roger; Hanssen, Eric; Gervinskas, Gediminas; Hock Ng, Soon; Khanh Truong, Vi; Luque, Pere; Ramm, Georg; Wösten, Han A B; Crawford, Russell J; Juodkazis, Saulius; Maclaughlin, Shane
(2021) Journal of Colloid and Interface Science, volume 603, pp. 886 - 897
(Article)
Abstract
HYPOTHESIS: The ability exhibited by insect wings to resist microbial infestation is a unique feature developed over 400 million years of evolution in response to lifestyle and environmental pressures. The self-cleaning and antimicrobial properties of insect wings may be attributed to the unique combination of nanoscale structures found on the
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wing surface. EXPERIMENTS: In this study, we characterised the wetting characteristics of superhydrophobic damselfly Calopteryx haemorrhoidalis wings. We revealed the details of air entrapment at the micro- and nano scales on damselfly wing surfaces using a combination of spectroscopic and electron microscopic techniques. Cryo-focused-ion-beam scanning electron microscopy was used to directly observe fungal spores and conidia that were unable to cross the air-liquid interface. By contrast, bacterial cells were able to cross the air-water interface to be ruptured upon attachment to the nanopillar surface. The robustness of the air entrapment, and thus the wing antifungal behaviour, was demonstrated after 1-week of water immersion. A newly developed wetting model confirmed the strict Cassie-Baxter wetting regime when damselfly wings are immersed in water. FINDINGS: We provide evidence that the surface nanopillar topography serves to resist both fungal and bacterial attachment via a dual action: repulsion of fungal conidia while simultaneously killing bacterial cells upon direct contact. These findings will play an important role in guiding the fabrication of biomimetic, anti-fouling surfaces that exhibit both bactericidal and anti-fungal properties.
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Keywords: Antibacterial, Antifungal, Self-cleaning, Superhydrophobic, Electronic, Optical and Magnetic Materials, Biomaterials, Surfaces, Coatings and Films, Colloid and Surface Chemistry
ISSN: 0021-9797
Publisher: Academic Press Inc.
Note: Funding Information: The authors acknowledge ANSTO and the Australian Synchrotron for use of the IR beamline. Funding from the Australian Research Council (ARC) Industrial Transformation Research Hubs Scheme (ARC Research Hub for Australian Steel Manufacturing, Project Number IH130100017) and ARC Industrial Transformation Training Centre (ITTC) scheme (Project number IC180100005) are gratefully acknowledged. The authors acknowledge the technical services of the RMIT microscopy and microanalysis facility (RMMF), and the use of instruments and assistance at the Monash Ramaciotti Centre for Cryo-Electron Microscopy, a Node of Microscopy Australia. Funding Information: The authors acknowledge ANSTO and the Australian Synchrotron for use of the IR beamline. Funding from the Australian Research Council (ARC) Industrial Transformation Research Hubs Scheme (ARC Research Hub for Australian Steel Manufacturing, Project Number IH130100017) and ARC Industrial Transformation Training Centre (ITTC) scheme (Project number IC180100005) are gratefully acknowledged. The authors acknowledge the technical services of the RMIT microscopy and microanalysis facility (RMMF), and the use of instruments and assistance at the Monash Ramaciotti Centre for Cryo-Electron Microscopy, a Node of Microscopy Australia. E.P.I, D.P.L, and S.J. conceived the study and designed the experiments. E.P.I supervised the whole work. A.A.M, P.L and D.P.L measured the antibiofouling property of the wings. A.A.M performed PCR. S.H.N contributed to the contact angle experiments with specialized techniques. D.P.L, R.C, E.H, V.K.T, G.G, G.R carried out the cryo experiments. V.B and S.J provided computational analyses of air entrapment. D.P.L wrote the paper. All authors contributed to editing and approved the final manuscript. All data needed to evaluate the conclusions in the paper are present in the paper and/or the Supplementary Materials. Additional data related to this paper may be requested from the authors. Publisher Copyright: © 2021 Elsevier Inc.
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