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Self-Nanoemulsification of Healthy Oils to Enhance the Solubility of Lipophilic Drugs
Published on: July 27, 2022
Biocompatible microemulsions based on limonene: formulation, structure, and applications
Vassiliki Papadimitriou1, Stergios Pispas, Stauroula Syriou
1Institute of Biological Research & Biotechnology, Theoretical and Physical Chemistry Institute, National Hellenic Research Foundation, 48, Vassileos Constantinou Avenue, 11635, Athens, Greece. vpapa@eie.gr
Langmuir : the ACS Journal of Surfaces and Colloids
|February 29, 2008
Summary
This study prepared biocompatible microemulsions using R-(+)-limonene and explored their properties. 1-propanol as a co-surfactant enhanced microemulsion formation and facilitated lipase-catalyzed esterification, unlike 1,2-propanediol.
Area of Science:
- Physical Chemistry
- Colloid and Surface Chemistry
- Biochemistry
Background:
- Biocompatible microemulsions are essential for various applications, including drug delivery and enzymatic reactions.
- Understanding the phase behavior and interfacial properties of microemulsions is crucial for their effective formulation.
- R-(+)-limonene offers a sustainable and biocompatible base for microemulsion systems.
Purpose of the Study:
- To prepare and characterize biocompatible water-in-oil (w/o) microemulsions using R-(+)-limonene.
- To investigate the influence of co-surfactants (1-propanol vs. 1,2-propanediol) on microemulsion properties and phase diagrams.
- To evaluate the performance of solubilized lipase (Rhizomucor miehei) in enzymatic esterification reactions within these microemulsions.
Main Methods:
- Pseudo-ternary phase diagrams were constructed at 30°C to map microemulsion regions.
- Electron Paramagnetic Resonance (EPR) spectroscopy with spin-labeling was used to study interfacial properties.
- Dynamic Light Scattering (DLS) and electrical conductivity measurements were employed to characterize droplet size and system conductivity.
Main Results:
- 1-propanol significantly increased the microemulsion zone area compared to 1,2-propanediol.
- EPR studies revealed that 1-propanol leads to a more flexible interface with less tight lecithin packing.
- DLS showed aqueous domain radii of 60-180 nm with 1-propanol, and conductivity indicated a percolation threshold at >4% water.
- Lipase catalyzed esterification of long-chain fatty acids with 1-propanol, but not with 1,2-propanediol.
Conclusions:
- The choice of co-surfactant critically impacts microemulsion structure, interfacial dynamics, and enzymatic activity.
- 1-propanol is a superior co-surfactant for forming stable microemulsions and enabling lipase-catalyzed esterification with long-chain fatty acids.
- The observed differences are attributed to lipase specificity or alcohol-induced structural changes in the microemulsion system.
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