Poster Presentation Australian Society for Microbiology Annual Scientific Meeting 2013

Hierarchical construction of the surfaces of dragonfly wings on the micro- and nano-scale (#296)

Song Ha Nguyen 1 , Hayden Webb 1 , Jafar Hasan 1 , Vi Khanh Truong 1 , Robert Lamb 2 , Xiaofei Duan 2 , Mark Tobin 3 , Peter Mahon 1 , Russell Crawford 1 , Elena Ivanova 1
  1. Swinburne University of Technology, Hawthorn, VIC, Australia
  2. The University of Melbourne, Parkville, VIC, Australia
  3. Australian Synchrotron, Clayton, VIC, Australia
A number of natural surfaces such as insect wings exhibit superhydrophobic and self-cleaning properties, and therefore have potential industrial applications. Some insect wing surfaces were recently reported to possess bactericidal activities. In an effort to understand the mechanisms responsible for the antibacterial effect of insect wings, a combination of advanced microscopic, spectroscopic and chromatographic techniques, i.e., scanning electron (SEM) microscopy, Synchrotron-sourced Fourier-transform infrared microspectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS) depth profiling and gas chromatography-mass spectrometry (GCMS), were employed to evaluate the physical and chemical properties of the surfaces of the dragonfly Hemianax papuensis wings (donated by Melbourne Museum). The cross-sectional view of the wing surface revealed that the wing is comprised of three main layers. These include two epicuticular layers of approximately 180-200 nm thickness on the dorsal and ventral surfaces, and an intracuticular layer of approximately 2.5 µm thickness, where the bulk membrane is located. Using GCMS, it was found that hexadecanoic acid, octadecanoic acid and n-alkanes were the predominant components on the outermost surface of the epicuticular layer of the wing. The location of particular classes of compounds was determined using XPS depth profiling. The results indicated that the hexadecanoic acid is present mostly as a thin layer (approximately 30 nm in thick) on the outer surface of the epicuticle, and also present with octadecanoic acid within a deeper layer. Aliphatic compounds were found to be present across the wing membrane, forming a discrete layer which appeared to be different from that of the inner and outer layer of the epicuticle.