Niosome-Based Supramolecular Biosolvents: Aligning Analytical Efficiency with Green Chemistry Criteria

Chemists have long relied on liquids to pull useful substances out of solid materials, a process essential for testing food safety, checking environmental health, and discovering new medicines. However, the traditional liquids used for this job are often derived from petroleum, can be toxic, and are difficult to dispose of safely. In recent years, scientists have turned their attention to "green" alternatives: solvents that are safer for people and the planet. Among the most promising of these are supramolecular solvents. Unlike ordinary liquids that are just a mix of molecules floating freely, these are structured liquids. They form when tiny building blocks, called amphiphiles, naturally arrange themselves into organized clusters in water. These clusters create a unique environment with different zones that can grab onto a wide variety of substances at once, making them incredibly efficient at cleaning up samples. The challenge has been to create these structured liquids using ingredients that are not only effective but also fully sustainable, cheap, and safe to use in large quantities.

A team of researchers in Spain has now developed a new type of these structured solvents that meets these high standards. They created a liquid based on niosomes, which are tiny, bubble-like structures made from a common, food-safe ingredient known as Span 40. This ingredient is a type of fat-like molecule derived from sorbitol and palmitic acid, widely used in everything from cosmetics to food to keep mixtures stable. The researchers mixed this ingredient with water and a type of alcohol called 1-propanol, then added a small amount of salt to trigger a natural separation process. Instead of creating a messy sludge, the mixture spontaneously formed a distinct, clear liquid phase at room temperature. This new liquid is not a uniform soup; it is filled with billions of microscopic, flexible bubbles, each roughly the size of a virus, that are packed tightly together. These bubbles are the key to the solvent's power, acting as tiny containers that can hold water in their centers and alcohol in their walls, creating a versatile environment for trapping different chemicals.

The team tested this new solvent by trying to extract valuable nutrients from the leaves of the white mulberry tree, a plant known for its rich content of health-promoting compounds. They found that their new solvent was far superior to standard methods. When compared to using plain ethanol or 1-propanol, the new structured liquid pulled out significantly more of the plant's beneficial compounds. It increased the amount of total phenols by between 77 and 118 percent, flavonoids by 24 to 59 percent, and carotenoids by 8 to 35 percent. What makes this result particularly impressive is the diversity of the compounds it captured. The solvent successfully extracted molecules that ranged from very water-loving to very oil-loving, including complex sugar-linked structures and simpler forms, all in a single step. This suggests that the organized bubbles inside the solvent can interact with many different types of molecules simultaneously, providing a complete chemical fingerprint of the plant without needing multiple different solvents.

Beyond its performance, the solvent was designed to be truly sustainable. The process used to make it requires no heat and no special machinery; it happens naturally at room temperature. The ingredients are cheap, widely available, and renewable. The main component, Span 40, is a food additive that is non-toxic and breaks down easily in the environment. The alcohol used is also considered safe and can be produced from plant sources. While the alcohol component does mean the final liquid is flammable and requires standard safety precautions, the overall process avoids the heavy toxicity and environmental damage associated with traditional petroleum-based solvents. The researchers also showed that the tiny amount of salt used to create the solvent stays mostly behind in the waste water, meaning the final liquid is clean enough to be injected directly into sensitive scientific instruments for analysis without causing damage.

This work demonstrates that it is possible to build highly efficient, nanostructured solvents using very small amounts of surfactant to organize a large volume of liquid. The researchers found that the tiny bubbles they created were so effective that they could structure a solvent volume using less than half a percent of the amphiphile ingredient, a much lower concentration than previously thought necessary. By proving that these green, bio-based solvents can extract a wide range of complex chemicals from difficult plant materials, the study offers a practical path forward for analytical chemistry. It suggests a future where the tools used to analyze our food and environment are themselves safe, affordable, and kind to the planet, without sacrificing the precision scientists need to do their work.