Polymer coated carbon nanotubes could find a new use in drug delivery, claim Korean scientists.

Sangyong Jon, from Gwangju Institute of Science and Technology, and co-workers designed an amphiphilic polymer coating - that contains both hydrophilic and hydrophobic parts - for carbon nanotubes (CNTs).  They found that in vitro the coating made the CNTs dissolve better in water and plasma, and allowed them to conjugate to biomolecules.  Both are vital properties for drug delivery applications. 

It is known that CNTs assist in killing cancer cells when irradiated because of their near IR absorption property, explains Jon.  CNTs have also been shown in vitro to be able to deliver anticancer drugs to specific cells.  However several complications arise when this concept is moved into the body, he continues.  CNTs that remain dispersed in plasma for a reasonable amount of time, without aggregating or blocking capillary vessels, are needed. They also must not adsorb unwanted proteins onto their surface. And finally they need functional groups that can carry biomolecules and drugs.

Jon's polymers consist of three parts: a hydrophobic section that can anchor to the CNT's surface, a hydrophilic poly(ethylene glycol) part which blocks adsorption of unwanted proteins, and a carboxylic acid that can immobilise drugs for transport in the body.  'Compared to the amphiphilic polymers and polymer surfactants that were used to coat CNTs previously, CNTs coated with our polymers show much better dispersibility as well as stability in vitro,' says Jon.  The group also tested their coated CNTs for effective loading and delivery of an anticancer drug, doxorubicin, in vitro.  'Our results indicate that these coated CNTs may hold promise as a potential drug delivery vehicle,' says Jon.

Ali Khademhosseini, who researches biomaterials at Harvard-Massachusetts Institute Division of Health Sciences and Technology, highlights the potential of this work, 'researchers are extremely interested in using CNTs for drug delivery, this work takes a step in making this a reality.'

Jon says that the toxicity associated with CNTs is another major challenge for their future medical applications, but this coating should reduce this problem by making the CNTs more biocompatible. 'We hope the coated CNTs could be used to treat diseases such as cancer', he says.

Fay Riordan