A ukidama glass fishing float.
A ukidama glass fishing float.

A team of researchers from Okinawa Institute of Science and Technology Graduate University (OIST) in Japan has discovered a unique copper-silver nanoparticle structure in which a core of one element is surrounded by a ‘cage’ of the other element. The resultant nanoparticles resemble the traditional Japanese glass fishing floats covered with rope, known as ukidama, and are described in a paper in Nanoscale.

“The ukidama is a unique structure, which means that it can likely give us unique properties,” said Panagiotis Grammatikopoulos, first author and group leader of the OIST Nanoparticles by Design Unit. “The idea is that now that we know about this structure we may be able to fine tune it to our applications.”

The OIST researchers are continually working to create and design nanoparticles that can be used in biomedical technology. Specifically, the team works to design optimal nanoparticles for use in technologies like smart gas sensors that can send information about what is going on inside the body to a smartphone for better diagnoses. Another application is label-free biosensors that can detect chemical substances without the hindrance of fluorescent or radioactive labels. The novel ukidama nanostructure may help in these efforts.

“The more parameters that we can control the more flexibility we have in our applications and devices,” explained Mukhles Sowwan, author and head of OIST’s Nanoparticles by Design Unit. “Therefore, we need to optimize many properties of these nanoparticles: the size, chemical composition, crystallinity, shape and structure.”

The researchers discovered the ukidama structure when sputtering copper and silver atoms simultaneously, but independently, through a magnetron-sputtering system at high temperatures. When the atoms began to cool, they combined into bi-metallic nanoparticles. During the sputtering process, the researchers could control the ratio of silver to copper by varying the sputtering power. They found that the ukidama structure formed when copper was the dominant element, since silver atoms have a higher tendency to diffuse onto the nanoparticle surface. Based on these findings, the team was able to create simulations that clearly show how the ukidama nanoparticles form.

The team is now looking to see if this ukidama structure can be recreated in other types of nanoparticles. “We design and optimize nanoparticles for biomedical devices and nanotechnology,” said Sowwan. “Because the ukidama is a new structure, it may have properties that could be utilized in our applications.”

Co-author Antony Galea, formerly of the Nanoparticles by Design Unit, was responsible for the experimental portion of this study and has since moved to OIST’s Technology and Licensing Section. “Our aim is to take research created by OIST from the lab to the real world,” Galea said. “This is a way that work done at OIST, such as by the Nanoparticles by Design Unit, can benefit society.”

This story is adapted from material from OIST, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.