Evidence that gecko setae are coated with an ordered nanometer-thin lipid film

Published

June 9, 2022

Author(s)

Cherno Jaye, Daniel A. Fischer, Mette Rasmussen, Katinka Holler, Joe Baio, Stanislav Gorb, Tobias Weidner

Abstract

Motivated by the fascination of gecko adhesion based on the fibrous setae at the tips of their toe pads and their potential for biomimetic applications, the adhesion mechanism has been studied in detail. While the mechanism has been shown to be based on van- der-Waals interactions of myriads of spatula at the distal part of setal arrays, there are still open questions about the molecular structure of gecko setae. Recently it has been shown that phospholipids are associated with the spatula surface. However, the extent, to which spatula and setae are coated with lipids, as well as the structure of lipids at the spatula surface are still unclear. Since lipids can modulate adhesion properties and surface hydrophobicity and can therefore play an important role in adhesion, we have studied the molecular structure of lipids at spatula surfaces using near-edge X-ray absorption fine structure (NEXAFS) imaging. Nitrogen and carbon K-edge spectra showed that a mere nanometer-thin layer of lipids is present at the spatula surface. Angle-resolved NEXAFS images provide evidence that the lipids are forming ordered, densely packed layers. Dense lipid layers can effectively render surface hydrophobicity and may play a key role for the gecko adhesive system by enhancement of hydrophobic-hydrophobic interactions with potential substrates.

Citation

Biology Letters

Volume

18

Pub Type

Journals

Download Paper

https://doi.org/10.1098/rsbl.2022.0093

Local Download

Keywords

Adhesion, friction, attachment, toe pad, reptiles, integument, NEXAFS spectro-microscopy, biotribology

Citation

Jaye, C. , Fischer, D. , Rasmussen, M. , Holler, K. , Baio, J. , Gorb, S. and Weidner, T. (2022), Evidence that gecko setae are coated with an ordered nanometer-thin lipid film, Biology Letters, [online], https://doi.org/10.1098/rsbl.2022.0093, https://tsapps.nist.gov/publication/get_pdf.cfm?pub_id=934029 (Accessed May 10, 2024)