Advanced encapsulation techniques for essential oils: enhancing stability and bioavailability through nanocarriers

What if the key to unlocking essential oils' full potential lies in a green, tunable solvent—one that can be fine-tuned like a musical instrument? This study reveals ten new natural deep eutectic solvents that might just be the answer.

Essential oils are potent but fragile. Their volatility and sensitivity to light, heat, and oxygen limit their use. Encapsulation in nanocarriers offers a shield, but the carrier itself must be safe, effective, and sustainable. Enter natural deep eutectic solvents (NADESs)—green, tunable media that could revolutionize how we stabilize and deliver these precious compounds.

In a new study, scientists synthesized ten type-V NADESs using urea as a hydrogen-bond acceptor and three groups of donors: glycerol, organic carboxylic acids, and carbohydrates. They characterized these solvents in detail, measuring density, surface tension, and spectral properties. The densities ranged from 1.243 to 1.361 g/cm³, and high molar refraction and polarizability values pointed to tightly packed, hydrogen-bonded networks.

Surface tension varied widely—from 46.9 to 80.3 mN/m—defining low, medium, and high polarity systems. Solvatochromic analysis using Nile Red, betaine 30, and Kamlet–Taft parameters revealed that all NADESs are highly polar, comparable to water, but with distinct hydrogen-bond donating and accepting abilities depending on the third component. This means they can be fine-tuned for specific applications, from extraction to solvation of bioactive compounds.

The results highlight these NADESs as green, versatile tools for enhancing the stability and bioavailability of essential oils through advanced encapsulation techniques. By choosing the right donor, scientists can tailor the solvent's properties to match the needs of the active ingredient, opening doors to more effective and sustainable formulations.

Key Points

• Ten type-V NADES synthesized and characterized.
• Density 1.243–1.361 g/cm³, high molar refraction.
• Surface tension 46.9–80.3 mN/m, tunable polarity.