doi:10.1038/nindia.2011.69 Published online 16 May 2011
Researchers have successfully produced new amino-acid-derived ionic liquid surfactants that could prevent the harmful growth of marine algae. The surfactants could also aid the synthesis of nanomaterials and biomolecular devices.
Algal growth has adverse effects on fishing, tourism and human health. Biosurfactants such as glycolipids and lipoproteins can counter algal growth, but are difficult and expensive to produce. In recent years, ionic liquid surfactants have emerged as promising alternatives because of their high water solubility and ability to self-assemble. However, some ionic liquid surfactants are loaded with halogen atoms, which, if released, can be potentially harmful to the surrounding environment.
The researchers used natural amino acids such as glycine, alanine, valine, glutamic acid, proline and sodium lauryl sulphate to produce eco-friendly amino-acid ionic liquid surfactants (AAILSs). They then exposed the AAILSs to Amphidinium cartarae, a toxic marine alga, to test their ability for preventing algal bloom. Results showed that very low concentrations of AAILSs were sufficient to kill algae without any detrimental effects on the surrounding environment.
The surface tension of the AAILS solutions reached the value of natural seawater within 36 hours, which indicates rapid and complete biodegradability. The very high biodegradability of AAILSs ensures that they disappear quickly after halting algal bloom. In addition to checking algal growth, the surfactants also helped shape nanostructures such as spheres, cubes and star-shaped structures from cerium ammonium carbonate solution.
"The AAILSs are highly water-soluble, biodegradable and non-toxic, which makes them potential candidates for drug-delivery applications," says lead researcher Arvind Kumar from the Central Salt and Marine Chemicals Research Institute, Gujarat. He adds that these AAILSs have a higher surface activity than conventional surfactants.
- Trivedi, J. T. et al. Task-specific, biodegradable amino acid ionic liquid surfactants. ChemSusChem doi: 10.1002/cssc.201100065 (2011)