Nanospnges clean up

Versatile nanotechnology to deliver drugs and decontaminate soil.

A team of French researchers has developed water-soluble hydrophobic dendrimers which they claim could act as nanosponges for lipophilic drugs.

Jean-Pierre Majoral, Anne-Marie Caminade and colleagues from the Laboratoire de Chemie de Coordination CNRS in Toulouse, France, built up water-soluble phosphorus dendrimers (G ₅N ⁺) from an octaaldehyde metal-free phthalocyanine core. ¹

These dendrimers have a hydrophobic interior and hydrophilic end-groups. Solubilised in water, they behave like solid colloidal particles, which swell and ’bloom’ like dry sponges to give micelle-like compounds as increasing amounts of tetrahydrofuran are added.

The dendrimer also acts as a buffer, regulating the viscosity of the solution, illustrating how the complexity of interactions between the dendrimer and its environment could make it a very flexible nanotool.

Meanwhile, a team of researchers from Cornell University, US, and Samchok National University, South Korea, has synthesised nanoparticles that could act as nanosponges, mopping up polynuclear aromatic hydrocarbons (PAH) from contaminated soil. ²

The amphiphilic polyurethane particles consist of polyurethane acrylate anionomer precursor chains that crosslink in water. The resulting nanoparticles are colloidal in size (17-97nm). According to the researchers, they enhance PAH desorption and transport in a similar way to surfactant micelles but have the advantage of not adsorbing to the surface of soil particles.

The researchers suggest that the particles could be engineered to achieve different properties for various contaminants and soil conditions.

Thus, by changing the size of the hydrophobic segment, and the charge density or size of the pendant water-soluble chains on the particle surface, the particles could be made to move through different soils to the surface where they could be gathered up and flushed clean of contaminants.

Hamish Kidd