Clumps of gold nanoparticles retain heat or drugs to kill cancer cells

Gold nanoparticles held together with silicon dioxide retain heat from near-infrared light.--Courtesy of ETH Zurich

Researchers at Switerland's ETH Zurich have developed gold nanoparticles that could act as a cancer treatment by heating up and destroying tumor cells when they absorb near-infrared light. And the scientists have made the so-called plasmonic particles in a way that can be reproduced in bulk.

To imbue gold nanoparticles--which are usually spherical in shape--with the ability to absorb light and emit heat, they must be collected together in a specific configuration, according to a report from the university. To do this, the team coated each individual gold nanoparticle with a silicon dioxide layer, which clumps the particles together into rods, giving them this ability to retain and expel heat.

What's more, the silicon dioxide prevents the particles from deforming when they heat up, and shape is a crucial part of the process: The rod configuration has been demonstrated to give the gold particles their plasmonic ability.

The team also added iron oxide particles to the gold aggregates so that they can be "steered" toward a tumor and accumulate there. In this way, the particles can enter deep tissues of a tumor and release the heat in places where, normally, near-infrared light couldn't reach.

The gold nanoparticles could also be used to carry drugs to tumors if their release mechanism were made temperature-responsive, the scientists say. Once the particles are inside a tumor, for instance, and have been heated with light, they could release a drug there because of a programmed temperature resistance.

The researchers tested the particles in vitro in breast cancer cells, killing them off, but they say many questions still need to be answered before testing them out in humans. They published the study in the journal Advanced Functional Materials.

- here's the ETH Zurich report
- and the Advanced Functional Materials abstract

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