Templating core–shell particles using metal ion-chelating biosurfactants--颗粒学报PARTICUOLOGY

Yeh, C.-M., Jarrett, T., Gao, Y., Zhao, C.-X., Whittaker, A., Sainsbury, F., & White, A. L. (2022). Templating core–shell particles using metal ion-chelating biosurfactants. Particuology, 64, 145-152. https://doi.org/10.1016/j.partic.2021.06.003

Templating core–shell particles using metal ion-chelating biosurfactants

Ching-Min Yeh ^{a b}, Thomas Jarrett ^a, Yuan Gao^a, Chun-Xia Zhao ^a, Andrew Whittaker ^a^b, Frank Sainsbury ^{a d *}, Alison L. White ^{a b c *}

a Australian Institute of Bioengineering and Nanotechnology, The University of Queensland, St. Lucia, Queensland, 4072, Australia
b ARC Centre of Excellence in Convergent Bio-Nano Science and Technology, The University of Queensland, St Lucia, 4072, Australia
c CSIRO Probing Biosystems Future Science Platform, Brisbane, Australia
d Centre for Cell Factories and Biopolymers, Griffith Institute for Drug Discovery, Griffith University, Brisbane, QLD, 4111 Australia

10.1016/j.partic.2021.06.003

Volume 64, May 2022, Pages 145-152

Received 24 March 2021, Revised 31 May 2021, Accepted 14 June 2021, Available online 24 June 2021, Version of Record 17 December 2021.

E-mail: f.sainsbury@griffith.edu.au; a.tasker@uq.edu.au

Highlights

• Designer biosurfactant AM1 forms stable oil/water emulsions with Pd(II) ions.

• Pd(II)-AM1 interfacial network remains stable at acidic pH.

• Interaction of histidine residues with Pd(II) is by a different mechanism than Zn(II).

• Pd(II)-AM1 stabilised interface catalyses gold shell deposition around emulsions.

Abstract

Designer biosurfactants can be used to stabilise and functionalise interfaces. One particularly promising use is the stabilisation of oil-in-water emulsions, enabling fine tuning physical, chemical and biological surface properties. The ability of emulsion systems to carry high payloads makes them attractive for applications in medicine, food and fragrances, and cosmetics. However, they have limited long-term stability. Here we sought to use the metal ion-chelating ability of the biosurfactant peptide, AM1, to precipitate the formation of a gold metal shell on AM1-stabilised emulsions by electroless plating. We found that replacing the commonly used zinc(II) with palladium(II) for coordination by histidine residues of adjacent AM1 peptides produced interfacial films that maintained elasticity at acidic pH. Proton NMR suggested a coordination mechanism independent of the imidazole ring of the histidines. Nevertheless. stabilisation of emulsions at low pH enabled the deposition of a gold shell, albeit by an unexpected mechanism. We propose that gold nanoparticles forming in bulk are adsorbed onto the peptide-stabilised interface, accumulating into a particulate coating. The resulting one-step method for nanoparticle precipitation and shell formation will be useful for the creation of biocompatible core–shell particles for applications where large payloads of hydrophobic active compounds require stability over long time periods.

Graphical abstract

Keywords

Biosurfactants; Emulsion; Core-shell particles; Electroless plating; Histidine; Interfacial elasticity

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