Gold nano-particles can help develop smarter biosensors, drug delivery systems: Study

Scientists have found that the use of gold nano-particles can help develop smarter bio-sensors, better diagnostic tools and more reliable drug delivery systems because of the manner in which they behave when they are exposed to certain molecules and salts.

Gold nano-particles are employed in powerful optical technologies and they are considered to be special because they interact with light in unique ways. Their colour and optical response depend on whether they are alone or clustered together.

When they aggregate, their optical properties change or adapt, which is the reason they are widely used in biosensors, environmental monitoring and imaging.

Scientists from SN Bose National Centre for Basic Sciences have found a way to control this aggregation or clustering. Understanding the factors governing gold nano-particle aggregation is crucial for optimising plasmonic sensors and enhancing detection methodologies, the researchers said in their study that has been published in Analytical Chemistry, a peer-reviewed scientific journal published by the American Chemical Society.

“This study provides critical insights into the physicochemical interactions governing nano-particle stability, which can inform the development of advanced nano-biosensors. Our findings contribute to a deeper understanding of gold nano-particle aggregation mechanisms and offer new perspectives for designing responsive plasmonic systems for biomedical and analytical applications,” the researchers said.

To give a perspective of the size, a nano-particle is several thousand times smaller than the width of a human hair. According to scientists, at the nanoscale, particles behave differently than their normal form, leading to novel electrical, optical and physical properties. Biologically, their small size allows them to easily penetrate cells and tissues, making them valuable in medical applications.

The team led by Prof Manik Pradhan, introduced two molecules, one of Guanidine Hydrochloride (GH), a powerful salt known for breaking proteins apart in laboratories and L-Tryptophan (LT), an amino acid that is consumed daily and found in proteins that are often associated with sleep and relaxation. They found that on contact with GH, gold nano-particles quickly lost their repulsion and clumped into dense, compact clusters. But when LT was added, the characteristics changed and instead of tight clumps, the nano-particles formed loser, branched networks.

The team employed a highly sensitive optical technique called Evanescent Wave Cavity Ringdown Spectroscopy to study this. They found that LT stabilised the GH ions, softening their effect and leading to slower aggregation and a new, open structure.