McGill University researchers have developed a new low-cost method to buildDNA nanotubes block by block. It could help pave the way for scaffolds made from DNA strands for applications such as optical and electronic devices or smart drug-delivery systems.

The current method of constructing DNA nanotubes is based on spontaneous assembly of DNA in solution, which is vulnerable to structural flaws.

The new technique, reported Monday Feb. 23 in Nature Chemistry, promises to reduce such flaws and also makes it possible to better control the size and patterns of the DNA structures, the scientists report.

“Just like a Tetris game, where we manipulate the game pieces with the aim of creating a horizontal line of several blocks, we can now build long nanotubes block by block,” said Amani Hariri, a PhD student in McGill’s Department of Chemistry and lead author of the study.

“By using a fluorescence microscope we can further visualize the formation of the tubes at each stage of assembly, as each block is tagged with a fluorescent compound that serves as a beacon. We can then count the number of blocks incorporated in each tube as it is constructed.”

This new technique was made possible by the development in recent years of single-molecule microscopy.

That research has enabled scientists to view at the nanoscale by turning the fluorescence of individual molecules on and off. (That groundbreaking work won three U.S.- and German-based scientists the 2014 Nobel Prize in Chemistry.)

The resulting “designer nanotubes” approach promises to be far cheaper to produce on a large scale than those created with DNA origami — another technique for using DNA as a nanoscale construction material — according toHanadi Sleiman, who co-authored the new study and holds the Canada Research Chair in DNA Nanoscience.

Funding for the research was provided by the Natural Sciences and Engineering Research Council of Canada, the Canada Foundation for Innovation, NanoQuébec, the Canadian Institutes of Health Research, and the Fonds de recherché du Québec – Nature et technologies.