Shape-shifting nanoparticles to deliver drugs

Toronto: Scientists have designed a set of shape-shifting nanoparticles attached to strands of DNA that can deliver drugs directly to cancer cells, while minimising side effects such as hair loss and skin damage.

Many cancer drugs target fast-growing cells. Injected into a patient, they swirl around in the bloodstream acting on fast-growing cells wherever they find them.

That includes tumours, but unfortunately also hair follicles, the lining of your digestive system, and your skin.

Professor Warren Chan from the University of Toronto has spent the last decade figuring out how to deliver chemotherapy drugs into tumours - and nowhere else.

No two tumours are identical. Early-stage breast cancer may react differently to a given treatment than pancreatic cancer, or even breast cancer at a more advanced stage, researchers said.

Which particles can get inside which tumours depends on multiple factors such as the particle's size, shape and surface chemistry.

Researchers studied how these factors dictate the delivery of small molecules and nanotechnologies to tumours, and have now designed a targeted molecular delivery system that uses modular nanoparticles whose shape, size and chemistry can be altered by the presence of specific DNA sequences.

"We're making shape-changing nanoparticles. They're a series of building blocks, kind of like a LEGO set," said Chan.

The component pieces can be built into many shapes, with binding sites exposed or hidden. They are designed to respond to biological molecules by changing shape, like a key fitting into a lock.

These shape-shifters are made of tiny chunks of metal with strands of DNA attached to them. Chan envisions that the nanoparticles will float around harmlessly in the blood stream, until a DNA strand binds to a sequence of DNA known to be a marker for cancer.

When this happens, the particle changes shape, then carries out its function - it can target the cancer cells, expose a drug molecule to the cancerous cell, or tag the cancerous cells with a signal molecule.

The research was published in the journals PNAS and Science.