High-Load Borage Oil Nanoemulsion Development via Polyol-Free D‑Phase Emulsification
Jéssica Fagionato Masiero1, Jonnatan Julival Santos2, Andriéli Bacega3
1Department of Pharmacy, Faculty of Pharmaceutical Sciences, University of São Paulo, Avenida Professor Lineu Prestes 580, Cidade Universitária, CEP: 05508-000 São Paulo, São Paulo, Brazil.
ACS Omega
|February 23, 2026
Summary
This study developed stable borage oil nanoemulsions using a novel D-phase emulsification method without alkyl polyols. The scalable, solvent-free process yielded safe, high-concentration formulations with excellent physical stability.
Area of Science:
- Pharmaceutical Sciences
- Materials Science
- Colloid and Surface Chemistry
Background:
- Nanoemulsions offer enhanced bioavailability for poorly soluble compounds like borage oil.
- Traditional emulsification methods often require complex hydrophilic-lipophilic balance adjustments and organic solvents.
- Developing stable, high-concentration nanoemulsions with minimal surfactant is crucial for pharmaceutical applications.
Purpose of the Study:
- To develop borage oil nanoemulsions using a D-phase emulsification (DPE) method, excluding alkyl polyols.
- To optimize formulation parameters (borage oil, surfactant, initial water concentrations) for desired particle size and stability.
- To assess the physicochemical properties, long-term stability, and in vivo safety of the developed nanoemulsions.
Main Methods:
- Utilized D-phase emulsification (DPE) with polysorbate 80 as the surfactant, achieving high borage oil concentrations (up to 50% w/w).
- Employed a Box-Behnken design to investigate the impact of key formulation variables on nanoemulsion characteristics.
- Characterized formulations using dynamic light scattering, zeta potential measurements, microscopy, X-ray diffraction, and thermal analysis.
- Performed scale-up studies to 1 kg and conducted in vivo toxicity assessments in the Galleria mellonella model.
Main Results:
- Optimized formulations exhibited spherical droplets (300-400 nm) with narrow size distributions (Polydispersity Index < 0.3) and robust zeta potential (<-20 mV).
- Nanoemulsions demonstrated excellent physical stability for up to 12 months under tested conditions.
- Microscopy and diffraction analyses confirmed the amorphous or liquid crystalline state of the borage oil within the nanoemulsions.
- Scale-up to 1 kg maintained comparable physicochemical properties, and in vivo toxicity studies showed no significant adverse effects.
Conclusions:
- The DPE method provides a scalable, solvent-free approach for producing stable, high-concentration borage oil nanoemulsions.
- Initial water concentration was identified as a critical factor in reducing particle size and enhancing stability.
- The developed nanoemulsions exhibit favorable physicochemical properties and safety profiles, suggesting potential for pharmaceutical applications.
