DNA nanostructures designed for drug delivery remain a technical challenge

A cautionary tale for researchers working on selective drug delivery
A cautionary tale for researchers working on selective drug delivery. Credit: McGill University

Many studies indicating that DNA nanostructures can enter cells more readily than simple DNA strands are flawed, according to researchers at McGill University.

In a paper published in the American Chemical Society journal ACS Central Science, the McGill scientists demonstrate that many DNA cage nanostructures aren't taken up by cells to a significant extent. In a series of experiments, they show, instead, that the DNA nanostructures are degraded by enzymes outside the cell; a used for tracking purposes separates from the nanostructure; and the dye—or a small fragment containing the dye—is taken up in cells. The resulting fluorescent signal from within the cell is easily misinterpreted as indicating that the nanostructure, itself, has entered the cell. The group also shows that a commonly used fluorescence experiment (called FRET), involving between two dyes on a structure can also give erroneous results.

This finding is significant, because DNA strands are considered a promising tool for stopping the production of proteins associated with disease—yet delivering the strands into cells is a technical challenge. "Our is a cautionary tale for scientists working in the field of DNA/RNA delivery through selective therapeutics," says senior author Hanadi Sleiman, Professor of Chemistry at McGill and Canada Research Chair in DNA Nanoscience.

This problem could, however, be turned into an advantage, notes lead author Aurélie Lacroix, a graduate student in Prof. Sleiman's lab. "We could attach molecules on DNA nanostructures that make them enter diseased cells—for example cancer cells—but not normal cells. This would make it possible to selectively deliver drugs into diseased ." Sleiman also insists that some DNA nanostructures have shown exceptional promise in animal studies.

The McGill team offers recommendations and guidelines for scientists performing cell uptake studies using fluorescent dyes, to ensure that research is reliable and reproducible.

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More information: Aurélie Lacroix et al, Uptake and Fate of Fluorescently Labeled DNA Nanostructures in Cellular Environments: A Cautionary Tale, ACS Central Science (2019). DOI: 10.1021/acscentsci.9b00174
Journal information: ACS Central Science

Provided by McGill University
Citation: DNA nanostructures designed for drug delivery remain a technical challenge (2019, May 9) retrieved 7 April 2020 from https://phys.org/news/2019-05-dna-nanostructures-drug-delivery-technical.html
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