Gold particles could be used as part of a cancer
treatment that is less invasive than
chemotherapy.
Image: iStockphoto

An important breakthrough in cancer research has been made by a team of Swinburne University researchers, bringing a pioneering, non-invasive cancer treatment one step closer to being a reality.

The Centre for Micro-Photonics researchers, Professor Min Gu, Dr Jing Liang Li and Dr Daniel Day, have overcome a major hurdle in the advancement of photothermal therapy – an experimental technique hailed as a promising treatment for early stage cancer. Their research has been published in the Advanced Materials journal.

Photothermal therapy involves introducing a reactive compound into a patient’s tumour, which will absorb laser light and other forms of electromagnetic waves - this then heats the tumour cells and destroys them.

Using this concept, the Swinburne researchers developed gold nanorods – which are essentially minute gold particles – with a biological coating that targets cancerous cells. When introduced into a patient’s tumour, the nanorods will selectively attach to the cancerous cells, allowing researchers to target and destroy them with an infrared laser.

Professor Gu likens the photothermal procedure to a metal object getting very warm if it is left out in the sun. “Because we are using metallic nanorods, they heat up very quickly when a laser beam shines on them – this heat then destroys the cancerous cells they are attached to.”

According to the researchers, the biggest advantage of photothermal therapy over current cancer treatments is that it is potentially far less invasive, and researchers anticipate it will have fewer side effects. The gold nanorod solution will also be important in cancer detection, as the nanorods attached to tumour cells can be illuminated under infrared light.

“If we can catch the cancer early on before it metastasises, photothermal therapy will allow us to carry out targeted treatment at a cellular level. This will mean many patients with early stage cancer won’t have to go through radiation or chemotherapy, and the harsh side effects associated with these treatments,” said Dr Day.

Up until this point, researchers have typically used linearly polarised light for photothermal therapy. However they have continually encountered a major problem – the laser power needed to destroy cancerous cells is so high, that it could potentially kill the surrounding healthy cells as well.

The Swinburne researchers’ breakthrough came when they manipulated the laser beam, so that it oscillated with circular polarisation.

“The power needed to damage the cancerous cells was reduced significantly when we used a circularly polarised light, which means we could reduce the laser power needed to a medically safe level,” explained Gu.

“When the beam was oscillating in one direction, it wasn’t aligning with all of the nanorods. However when we converted it so that it was oscillating in a circular direction, this allowed the beam to match up with all of the nanorods in their various orientations.”

Now that they have made this vital breakthrough, the researchers hope that research into photothermal therapy can advance considerably.

One application they are looking at is combining this new technology with an optical endoscope – which would allow the researchers to target a wider range of cancers directly in the body, as well as other ailments such as ulcers.