Issue 4, 2023

Frictional behaviour of plant proteins in soft contacts: unveiling nanoscale mechanisms

Abstract

Despite the significance of nanotribology in the design of functional biomaterials, little is known about nanoscale friction in the presence of protein-coated soft contact surfaces. Here, we report a detailed investigation of frictional behaviour of sustainable plant proteins at the nanoscale for the first time, using deformable bio-relevant surfaces that achieve biologically relevant contact pressures. A combination of atomic force microscopy, quartz crystal microbalance with dissipation monitoring, and friction force microscopy with soft polydimethylsiloxane (PDMS, 150 kPa) surfaces was employed to elucidate the frictional properties of model plant proteins, i.e. lupine, pea, and potato proteins at the nanoscale while systematically varying the pH and ionic strength. Interactions of these plant proteins with purified mucins were also probed. We provide the much-needed direct experimental evidence that the main factor dictating the frictional properties of plant proteins is their affinity towards the surface, followed by the degree of protein film hydration. Proteins with high surface affinity, such as pea and potato protein, have better lubricating performance than lupine at the nanoscale. Other minor factors that drive lubrication are surface interactions between sliding bodies, especially at low load, whilst jamming of the contact area caused by larger protein aggregates increases friction. Novel findings reveal that interactions between plant proteins and mucins lead to superior lubricating properties, by combining high surface affinity from the plant proteins and high hydration by mucins. We anticipate that fundamental understanding gained from this work will set the stage for the design of a plethora of sustainable biomaterials and food with optimum nanolubrication performance.

Graphical abstract: Frictional behaviour of plant proteins in soft contacts: unveiling nanoscale mechanisms

Supplementary files

Article information

Article type
Paper
Submitted
10 Okt 2022
Accepted
26 Dez 2022
First published
26 Dez 2022
This article is Open Access
Creative Commons BY license

Nanoscale Adv., 2023,5, 1102-1114

Frictional behaviour of plant proteins in soft contacts: unveiling nanoscale mechanisms

E. Liamas, S. D. Connell and A. Sarkar, Nanoscale Adv., 2023, 5, 1102 DOI: 10.1039/D2NA00696K

This article is licensed under a Creative Commons Attribution 3.0 Unported Licence. You can use material from this article in other publications without requesting further permissions from the RSC, provided that the correct acknowledgement is given.

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