Abstract

Solid lipid nanoparticles (SLNs) consisting of the food grade surfactant lipid glyceryl stearate citrate (GSC) were prepared using hot melt emulsification and high-pressure homogenization. Flash-cooling of the resultant oil-in-water nanoemulsions led to the formation of GSC SLNs. The effective mean particle size of the SLNs was ~180 nm by dynamic light scattering and the volume-weighted mean particle size was ~152 nm by laser diffraction, with a zeta (ζ) potential of ~-49 mV. Effective mean particle size and ζ potential were stable for 24 wk. An equilibrium contact angle of ~108.7⁰ measured through oil phase was obtained, suggesting a wettable lipid surface. The melting curve of the SLNs obtained by differential scanning calorimetry showed a significantly lower melting point and broader peak as compared to the bulk GSC, which was attributed to the nano-scale particle size. Unusually, the cooling curve showed an identical crystallization temperature as that for the bulk GSC, which suggested surface heterogeneous crystallization of the SLNs. Subsequent heating-cooling cycles confirmed the existence of nanosized particles in the sample during thermal analysis. Transmission electron (TEM) and atomic force microscopy (AFM) both revealed anisometric, flattened SLNs with circular or elliptical shapes. SLNs were studied for their effectiveness as colloidal emulsifiers in oil-in-water (o/w) emulsions. The generated o/w emulsions had a volume-weighted mean droplet size of ~459 nm by laser diffraction and ζ potential of ~-43 mV. The emulsions were stable for up to 12 wk. as observed for macroscopic changes by inverted light microscopy. TEM images pointed to the presence of a Pickering-type network stabilizing the emulsions. With time, desorption of the SLNs from the oil droplet surface into the continuous aqueous environment, coupled with Ostwald ripening, resulted in destabilization of the emulsions. Overall, these results demonstrated that stabilization of o/w emulsions was achievable using SLNs as the sole emulsifiers.

Highlights

  • 1.0 IntroductionThe novelty of this thesis stems from the use of surface-active solid lipid nanoparticles as Pickering-type emulsion stabilizers

  • Desorption of the systems remain[1-3].1.1 Colloids and interfacesSolid lipid nanoparticles (SLNs) from the oil droplet surface into the continuous aqueous environment, coupled with Ostwald ripening, resulted in destabilization of the emulsions. These results demonstrated that stabilization of o/w emulsions was achievable using SLNs as the sole emulsifiers

  • SLNs were prepared by hot-melt emulsification and high-pressure homogenization

Read more

Summary

Introduction

1.0 IntroductionThe novelty of this thesis stems from the use of surface-active solid lipid nanoparticles as Pickering-type emulsion stabilizers. Solid lipid nanoparticles (SLNs) are submicron colloidal particles having particle size in the nanometre range (usually well below 1000 nm)[56] They are made from biocompatible lipids that melt when heated and solidify at room or body temperature[57, 58]. Solid lipid nanoparticles (or SLNs) are colloidal particulate systems with a mean particle size below 500 nm and a narrow particle size distribution[115, 129] They typically consist of physiological lipids that are biodegradable, non-toxic, cost effective, possess high dispersibility in an aqueous medium and offer ease of preparation and scale-up possibilities[172]. The exclusion of organic solvents and the ability to encapsulate both lipophilic and hydrophilic compounds within the lipid makes them an ideal carrier system for functional foods[87] It is well-known that the increase in specific surface area of a material is inversely proportional to its particle size. This effect greatly influences the interactions of nanoparticles with their local environment[173]

Objectives
Methods
Results
Conclusion
Full Text
Paper version not known

Talk to us

Join us for a 30 min session where you can share your feedback and ask us any queries you have

Schedule a call

Disclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.