Structural characteristics of oil-poor dilutable fish oil omega-3 microemulsions for ophthalmic applications

Nina Lidich, Abraham Aserin, Nissim Garti*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

22 Scopus citations

Abstract

Docosahexaenoic acid (DHA) promotes synthesis of anti-inflammatory prostaglandins and relief of dry eye symptoms. However, topical ophthalmic application of DHA is difficult because of its lipophilic property. Therefore, it is important to develop aqueous-based formulation with enhanced capabilities.Novel, unique water-dilutable microemulsions (MEs) were constructed to allow loading of naturally occurring rigid long-chain triglyceride of DHA (TG-DHA). The TG-DHA serves as solubilizate and as the oil phase, therefore preparation is poor in oil. The structural transformations of MEs upon water dilution were studied by SAXS, viscosity, electrical conductivity, self-diffusion NMR, DSC, cryo-TEM, and DLS techniques.At low water content a new type of water-in-oil (W/O) structure is formed. The glycerol/water phase hydrates the headgroups of surfactants, and the oil solvates their tails, forming "ill-defined bicontinuous domains". Upon further water dilution more structured bicontinuous domains of high viscosity are formed. After additional dilution, the mesophases invert to oil-in-water (O/W) droplets of ~8. nm.In the structures composed of up to 25. wt% water, the TG-DHA spaces and de-entangles the surfactant tails. Once the bicontinuous structures are formed, the surfactants and TG-DHA content decrease and their interfacial layer shrinks, leading to entanglement and buildup of viscous non-Newtonian mesophase. Above 70. wt% water TG-DHA is embedded in the core of the O/W droplets, and its effect on the droplets' structure is minimal.This new dilutable ill-defined microemulsion can be a potential delivery vehicle for ophthalmic TG-DHA transport.

Original languageEnglish
Pages (from-to)83-92
Number of pages10
JournalJournal of Colloid and Interface Science
Volume463
DOIs
StatePublished - 1 Feb 2016

Bibliographical note

Publisher Copyright:
� 2015 Elsevier Inc.

Keywords

  • Cryo-TEM
  • Drug delivery system
  • Dry eye syndrome
  • Omega fatty acids
  • Self-diffusion NMR
  • Solubilization

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