Gold Nanoparticle Breakthrough a Sustainability Fillip

University researchers have succeeded in producing gold nanoparticles without the need for toxic chemicals, a breakthrough that could have a a hugely positive sustainability impact.    

Gold nanoparticles are microscopic particles of gold that have unique physical, chemical and optical properties, making them critical across many industrial sectors, from medicine to electronics.

Yet gold nanoparticle production can be harmful to the environment, as it uses highly acidic gold chloride, which can damage soil and water when leaked. It also requires the use of toxic reducing agents that insinuate their way into small organisms, and then move up the food chain when these are consumed. 

Gold nanoparticle production also requires substantial electricity, which often is generated from fossil fuels, while water usage in the process is also high, which can strain local supplies in some areas. 

Plus, sourcing the gold itself can also pose environmental problems, because traditional gold mining uses cyanide compounds that pollute soil and water. 

But at Flinders University in Australia – which behind China is the world’s second largest gold mining country – researchers have produced a variety of different gold nanoparticles by adjusting water flow in a new vortex fluidic device (VFD), without the need for toxic chemicals.

A VFD is a sophisticated scientific instrument used in chemistry and materials science that consists of a tube that can spin at up to 10,000 rpm, a process that can create small, uniformly sized nanoparticles.

Flinders University researchers managed to produce a range of different types of gold nanoparticles by adjusting water flow in a new type of VFD that requires the use of no chemicals, only water. 

Sustainable gold nanoparticle process 'a breakthrough' 

The lead author of the study – published in the journal Small Science – is Badriah Mazen Alotaibi, who says the method is significant for the formation of nanomaterials “because it is a green process, quick, scalable and yields nanoparticles with new properties”.

“This discovery is a paradigm shift in how to make materials in a controlled way using water, with no other chemicals required,” he added.

If the process can be significantly scaled, then it has huge commercial potential. 

In the medical industry, gold nanoparticles are used for both diagnostic and therapeutic ends. They can be engineered to bind to cancer cells, making them visible in imaging techniques like computed tomography (CT) scans. 

Gold nanoparticles also show promise as drug delivery vehicles, because they can be coated with medications and guided to target specific diseased areas in the body, thus reducing side effects and improving treatment efficacy.

The electronics industry uses them in flexible and printable electronics, where they are incorporated into conductive inks that can be printed onto surfaces to create circuits. 

This technology is also behind the manufacture of flexible displays, wearable devices, and smart packaging. 

Gold nanoparticles are used, too, in the manufacture of more-efficient solar cells, contributing to the advancement of renewable energy technology.

Meanwhile, in the field of catalysis – the speeding up of chemical reactions – gold nanoparticles are used in the production of chemicals and the purification of hydrogen for fuel cells, making these industrial processes more efficient and environmentally friendly.

In environmental applications, gold nanoparticles are used for water purification, because they attract and bind to contaminants such as heavy metals and organic pollutants, removing them from water. After the nanoparticles can be recovered and reused, making this a sustainable solution for providing clean water.

The food industry is also exploring the use of gold nanoparticles as a means to detect food-borne pathogens, because these nanoparticles can be engineered to change colour when they come into contact with specific bacteria or toxins. 

In the researcher’s view, this discovery is a paradigm shift in how to make materials in a controlled way using water, with no other chemicals required.