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A new way to detect bacterial activity using gold nanoparticles


"Bacteria exist everywhere in an average person's daily life, and they usually develop into biofilms - a society of bacteria," explains Dr Huangxian Ju, director of the State Key Laboratory of Analytical Chemistry for Life Science at Nanjing University.

Just like a human society, a society of bacteria needs effective communication to grow and thrive. Bacteria in biofilms communicate by releasing small signal molecules, adjusting and coordinating their behaviour in response to the signals they receive.

This cell-to-cell communication is called 'quorum sensing' and it allows bacteria to monitor their environment and manage their activity, affecting things like the strength of an infection. Being able to detect and track this activity in real-time is key to understanding how bacteria cause disease, and crucially, how we can design better treatments to stop them.

A nano-gold sandwich

Previous methods for studying bacterial communication require long, complex processes that are often difficult to implement. Huangxian Ju and his team have designed an easy-to-assemble nanoparticle 'sticky note', which they can attach to a film of bacteria, enabling them to use an analytical technique to detect the bacteria's activity.

This 'sticky note' makes use of recent developments in the field of nanomaterials and its structure can be thought of as a sandwich. The 'bread' of the sandwich is made of a thin sheet of hexagonal boron nitride: a 2D material with similar properties to graphene. Between these layers are a filling of gold nanoparticles, which are needed for the analytical technique, known as Raman spectroscopy, to work.

Developing better antibiotics

Huangxian Ju's team were keen to design a material that would not only allow them to monitor bacterial activity, but also inhibit it. Antibiotics can be loaded onto the boron nitride sheets and the Raman spectroscopy used to monitor how effective these antibiotics are at killing the bacterial biofilm. The technique could help scientists develop and test new drugs to treat bacterial infections.

"The traditional techniques for studying quorum sensing need tedious pre-treatments, long operation periods with skilled technicians," says Huangxian Ju. "Therefore, it is highly desired for real-time tracing of the quorum sensing behaviour by a convenient and robust method in a low-cost manner.

"This 'sticky note' provides a versatile platform in investigating bacterial behaviours on hospital medical supplies, as well as developing antibiotic therapeutics with drug loading, and has wide applications in medicine and the pharmaceutical industry."

» Original publication

Source: Royal Society of Chemistry