Nanogold 'superstructures' are held together with DNA for cancer drug delivery

Warren Chan, University of Toronto

To make complex drug delivery structures of a particular size and shape, researchers in Canada have developed gold nanoparticle building blocks that can be "glued" together with bits of DNA. This could have particular importance in delivering drugs to treat breast cancer.

The team of scientists at the University of Toronto has come up with a multiple-component method for assembling the nanogold delivery particles using the flexibility and degradability of DNA to their advantage, which they describe in the journal Nature Nanotechnology.

The gold nanoparticles are assembled in a precise architecture, like a toothpick house held together with marshmallow joints. Once the "superstructure" has entered the cell, enzymes break down the DNA glue, and the gold nanoparticles are free to release their chemotherapeutic payloads, according to a report from the university.

"To get materials into a tumor they need to be a certain size," lead author Warren Chan said in a statement. "Tumors are characterized by leaky vessels with holes roughly 50-500 nanometers in size, depending on the tumor type and stage. The goal is to deliver particles small enough to get through the holes and 'hang out' in the tumor's space for the particles to treat or image the cancer. If the particle is too large, it can't get in, but if the particle is too small, it leaves the tumor very quickly."

In the study, the delivery strategy reduced the uptake of the nanoparticles by immune cells in the body and improved the in vivo tumor accumulation, as well as elimination later on. Overall, this should reduce the risk of toxicity from the drug and the nanoparticles.

The project, funded by the Canadian Institutes of Health Research, Natural Sciences and Engineering Research Council of Canada, Canadian Breast Cancer Foundation and Canada Foundation for Innovation, is still in its very early stages. The researchers are working on their understanding of how the DNA affects the design of the structures and their stability.

- here's the University of Toronto report
- and here's the abstract