Carbon nanohorns shape up for delivery

[nanoorg]

Carbon nanohorns (CNHs) could be a promising vehicle for intracellular delivery, say scientists in China. Researchers from Tianjin and Nankai Universities have come up with a simple way of isolating the nano-assemblies that overcomes the material’s insolubility in water and could help to prevent unwanted microscale agglomeration.

An individual CNH can be thought of as a "pudgy" version of a single-walled carbon nanotube with one end closed to give a cone- or horn-shaped cap. Strong van der Waals forces cause CNHs to assemble into desirable, spherical dahlia-flowerlike arrangements less than 100 nm in diameter.

"This distinctive structure gives CNHs a potential advantage over nanoparticles, nanorods and nanotubes for intracellular delivery," Fengboa Zhang of Tianjin's school of chemical engineering and technology said. "CNHs have huge surface areas and abundant cavities for absorbing and holding therapeutic drugs, genes or proteins."

To isolate the dahlia-flowerlike assemblies, the researchers dissolved untreated CNHs in a solution of gum arabic and water and then sonicated the mixture for 20 min. Raman spectroscopy revealed only mild damage to the CNHs following sonication. According to the team, the suspensions are stable for at least six months.

Zhang explained that the homogeneous ink-like suspension is biocompatible and appears to suit conjugation with biological cargos for intracellular delivery. Initial tests show that the CNHs have fast transport properties, which help to minimize enzymatic degradation of the attached drug, gene or protein during transit.

The researchers believe that CNHs will have superior biocompatibility compared with carbon nanotubes as high-purity CNHs can be prepared in the absence of metallic catalysts.

Building on its initial results, the team is now studying the interaction between CNHs and a range of therapeutic genes and proteins in detail.



Source: http://nanotechweb.org/articles/news/6/4/20/1



Story posted: 25th April 2007