Plasmonic nanoparticles form clusters, called plasmonic metamolecules, which interact with each other based on their geometries and relative positions.
Researchers from Aalto University in Finland have developed a way to manipulate the optical proprieties of these plasmonic nanostructures by changing their geometry.
“The challenge is to make the structures change their geometry in a controlled way in response to external stimuli,” says Anton Kuzyk from Aalto University. “In this study, structures were programmed to modify their shape by altering the pH.”
The plasmonic metamolecules were functionalized with pH-sensitive DNA locks that could be programmed to operate at a specific pH range. Then the metamolecules can be in either a “locked” state at a low pH or in a relaxed state at high pH. Both states offer different optical responses that create assemblies of several types of plasmonic metamolecules, each type designed to switch at different pH values.
Researchers say the ability to program nanostructures to perform specific functions in a certain pH window could have major implications in the field of nanomachines and smart nanomaterials with specific optical functionalities.
Controlling plasmonic metamolecules offers promise for the development of sensors, optical switches, transducers and phase shifters at different wavelengths. Future developments could lead to the development of controlled drug delivery.