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Faculty of Science

Research & Innovation

Paper of the Month

Using metallic silver nanoparticles to enhance fluorescence in organic dyes

Nicholas Dogantzis
Nicholas Dogantzis

Fluorescent dyes make it possible to mark—and therefore see more clearly through imaging—specific biological processes in living organisms. For example, it’s possible to observe molecular interactions within a living cell in a non-invasive manner. Being able to observe smaller and smaller features of objects advances our understanding of biological processes, which then makes the earlier detection of disease markers possible. Fluorescent bioimaging is one application of fluorescence activation that will contribute to new methods for diagnosing and treating illness.

When it comes to bioimaging, it stands to reason that creating a brighter fluorescence further aids in the examination of cell structures, which is precisely what Ryerson researchers have achieved. The team of Nicholas Dogantzis (MSc, Chemistry and Biology), Dr. Gregory Hodgson (postdoctoral researcher in the Impellizzeri Laboratory for Nanomaterials and Molecular Plasmonics) and supervisor Dr. Stefania Impellizzeri (Department of Chemistry and Biology) recently published a paper in The Royal Society of Chemistry’s Nanoscale Advances that describes the use of metallic nanoparticles to enhance fluorescence.

Schematic showing the "turning on" of a dye's fluorescence, followed by the enhancement of its fluorescence in the presence of silver nanoparticles (AgNP). The process was studied using single-molecule fluorescence microscopy.

“We found that we could use light to initiate a chemical reaction that activates the fluorescence of our dye, and then use triangular silver nanoparticles to further enhance that fluorescence many times over,” says lead author Nicholas Dogantzis. “By studying this chemistry at the single molecule level using microscopy, we now have a better understanding of how silver nanoparticles act to enhance the dye's fluorescence. This is a significant step forward in understanding the interactions between organic dyes and metal nanoparticles that lead to metal-enhanced fluorescence.”

While the theory of metal-enhanced fluorescence has been around for some time, there is still a lot of experimental work to be done in order to understand the many ways that different combinations of nanoparticles and dyes work together to impact fluorescence by different mechanisms. Developing a more general framework for predicting these complex interactions makes it possible to design better hybrid nanoparticle-dye systems.

The team is also working to combine metal-enhanced fluorescence with different types of light-activated fluorescence. These are two separate approaches which, until now, have not been combined. By using them together, there is potential to significantly increase their effectiveness, compared to using either one separately.

“This work further contributes to the field by demonstrating that techniques such as fluorescence microscopy, which are traditionally used by biologists, can be used to study cutting-edge nanomaterials science,” adds Dogantzis. “Incorporating these tools into the study of reactions and the properties of molecules, we can create a new way to do physical and organic chemistry. Moreover, by pushing the boundaries of these techniques, we aim to bring their use to a wider scientific audience and encourage interdisciplinary research.”

Dogantzis identifies the exploration of different nanoparticle-dye combinations as the next step in his research.

“This would allow for the development of even better fluorescence activation and enhancement systems. As part of this, I am also trying to maximize fluorescence by encapsulating dyes and nanoparticles inside of a confined superstructure so that they are always in close proximity to one another.”