Scientists believe that nanoscale devices may be created on large RNA arrays.

Scientists believe that nanoscale devices may be created on large RNA arrays.

When trying to build nanoscale objects the difficulty has always been how to control construction processes on such a scale. One solution adopted by scientists has been to take advantage of nature’s own construction material and build scaffolds out of DNA and proteins. These scaffolds then act as a framework for the construction of synthetic nanoscale objects.

Now, chemists at Purdue University, Indiana, US, have shown RNA to be an effective building material, and have created large 3D RNA arrays that could serve as templates for nanoscale devices. ’RNA combines the advantages of both DNA and proteins and puts them at the nanotechnologist’s disposal’, says team leader Peixuan Guo. ’It forms versatile structures that are also easy to produce, manipulate and engineer.’

The RNA strands used to build the arrays are based on strands found in a bacterial virus known as phi29, where they form part of a biological ’motor’ that packages DNA. At one end of each of these strands are two ’digits’ that can link with digits on other strands, providing they have complementary bases, as if holding hands.

Guo and his team created versions of these strands that had digits at both ends (termed twins), joined by a 50 base-pair helical region. They found that in mixtures containing two types of complementary twin, the strands would join together to form either circular structures or chains. However, in mixtures containing three different but complementary twins, hundreds of RNA strands would join together into huge arrays several microns in size. Further, the helical region joining the two ends of the RNA strand could twist and bend in three dimensions.

Guo’s team is now working on developing these arrays to serve as scaffolds for the construction of nanoscale devices such as diagnostic chips, sensors and drug delivery vehicles.

Jon Evans