Effect of pH and electrolytes on the colloidal stability of stearic acid–based lipid nanoparticles
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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.
KeywordsSolid lipid nanoparticles Hydration forces Steric stabilisation Tween® 20 Simulated body fluids Colloidal drug carriers
Brookhaven Instruments Corporation
Electrophoretic light scattering
Photon correlation spectroscopy
Research Training Program
Simulated body fluid(s)
Simulated gastric juice
Simulated intestinal fluid
Solid lipid nanoparticle(s)
We are thankful to Savithri Galappathie who prepared several solutions that were used throughout the course of this research.
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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