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Effect of pH and electrolytes on the colloidal stability of stearic acid–based lipid nanoparticles

  • Alexander F. Ife
  • Ian H. Harding
  • Rohan M. Shah
  • Enzo A. Palombo
  • Daniel S. Eldridge
Research Paper
First Online:
  • 42 Downloads

Abstract

Stearic acid–based solid lipid nanoparticles, stabilised with Tween® 20, were synthesised using a microwave-assisted microemulsion technique and their stability was tested in simulated blood plasma, several liquids mimicking gastrointestinal fluids and solutions containing different electrolyte compositions and pH levels. It was discovered that simulated blood plasma had a stabilising effect on the particles, as did simulated saliva and intestinal fluid, which was due to hydration forces, facilitated by the presence of hydrated cations. It was determined that the hydration stabilisation was pH dependent, with highly acidic conditions depriving the solid lipid nanoparticles of the negative charge required for the cations to hydrate the surface. In environments lacking hydrated cations, the particles were predominately reliant on steric stabilisation and were particularly susceptible to pH extremes due to hydrolysis/oxidation of the Tween® 20 layer. The results suggest that the SLNs have potential as a systemic drug carrier, as the physicochemical conditions of blood provide a stabilising environment that inhibits particle growth.

Keywords

Solid lipid nanoparticles Hydration forces Steric stabilisation Tween® 20 Simulated body fluids Colloidal drug carriers 

Abbreviations

BIC

Brookhaven Instruments Corporation

ELS

Electrophoretic light scattering

PCS

Photon correlation spectroscopy

RTP

Research Training Program

SBF(s)

Simulated body fluid(s)

SGJ

Simulated gastric juice

SIF

Simulated intestinal fluid

SLN(s)

Solid lipid nanoparticle(s)

SS

Simulated saliva

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Notes

Acknowledgements

We are thankful to Savithri Galappathie who prepared several solutions that were used throughout the course of this research.

Funding information

This study received financial support from the Australian Government’s Research Training Program (RTP).

Compliance with ethical standards

Conflict of interest

The authors declare that they have no conflict of interest.

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© Springer Nature B.V. 2018

Authors and Affiliations

  1. 1.Department of Chemistry and BiotechnologySwinburne University of TechnologyHawthornAustralia

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