Gold Nanorods and their Applications

Interview conducted by Zoe PeterkinJun 7 2018

AZoNanao spoke to Darren Rowles from Sona Nanotech about gold nanorods and their applications; in particular, examining the gold nanorods produced by Sona Nanotech.

What are gold nanorods?

Gold nanorods are microscopic gold nanoparticles that are have been elongated to resemble rods, rather than the traditional spherical shape. Since the early 2000s they have received a lot of attention from researchers because of their tunable optical properties, which makes them suitable for a wide range of applications, from technological to medical.

What are the applications of gold nanorods?

Because of their shape and the fact they can be produced in different lengths, gold nanorods have a number of advantages over other gold nanoparticles. Their tunable optical properties make them ideal for use in lateral flow assay diagnostic tests, while their improved absorption and scattering properties makes them potentially useful for drug delivery, cell imaging and photothermal therapy for cancer and liposuction.

How will they advance areas of the medical sector?

For the last two decades, scientists have been using spherical gold nanoparticles and CTAB-coated gold nanorods to research photothermal cancer therapy. However, their absorption characteristics and toxicity to biological materials means they are unsuitable for use in biological settings. Because of their near-infrared laser absorption properties and non-toxic coatings, Sona’s gold nanorods are effective photothermal agents.

What makes Sona Nanotech and its products unique?

The presence of the cytotoxin CTAB (cetyltrimethylammonium bromide) in gold nanoparticles has been a barrier to their adoption, as it meant they could not be used in-vivo. For more than a decade, manufacturers and users of gold nanorods have tried to overcome this issue by coating, removing or exchanging the CTAB. Sona Nanotech launched a project to develop toxin-free gold nanorods that could be manufactured cost-effectively and at volume. Sona’s products are unique because they contain no traces of CTAB whatsoever, whereas other suppliers make gold nanorods with CTAB and try to remove it later.

What is the difference between the two gold nanorod products Gemini and Omni?

Gemini is Sona’s product for diagnostic applications and Omni is for medical applications. Our Gemini rods are manufactured in a variety of lengths between 650nm and 1050nm, which makes them perfect for use in lateral flow diagnostic tests. They have distinct optical properties, resulting in contrasting colours, and can be read quantitively by a reader, making them ideal for use in multiplexed devices. Our Omni rods are specifically manufactured to be used in-vivo, with three distinct applications:

• Drug delivery: Our gold nanorods can be used to deliver drug molecules to cells, tissue, or organs. They are more efficient for delivering pain-relieving drugs than some other nanoparticles.
• Cell imaging: Our gold nanorods can be easily seen under a microscope, which means they can be used for cell imaging, yielding both qualitative and quantitative data.
• Photothermal therapy: Our gold nanorods can be used to target cancer cells inside the human body. Because they generate heat when excited with infrared light, they can be locally heated, destroying cancerous tissue and leaving healthy cells intact.

What does the future look like for gold nanorods?

I think gold nanorods have a bright future in a wide range of different applications. In terms of diagnostics, there is a growing demand for point-of-care testing, both in human and veterinary medicine. People have been predicting the demise of gold in lateral flow tests for a number of years now, in favour of other labels such as latex or quantum dots, but gold nanorods provide the multiple colours that make them ideal for multiplexing, which is where this technology is heading. In medical applications, gold nanorods could make a huge difference when it comes to drug delivery and cancer treatment, as I have already described. Outside of medicine, gold nanorods could be used in applications such as data storage and solar cell technology.

About Daniel Rowles

Darren Rowles is CEO and President of Sona Nanotech, a biotech company based in Halifax, Nova Scotia, Canada. He has worked with gold nanoparticle and lateral flow technology for almost 15 years.