Multimeric Rhodamine Dye-Induced Aggregation of Silver Nanoparticles for Surface-Enhanced Raman Scattering

Isotopic
variants of Rhodamine 6G (R6G) have previously been used
as a method of multiplexed detection for Surface Enhanced Raman Spectroscopy
(SERS), including protein detection and quantification. Challenges
exist, however, with producing long-term stable SERS signals with
exposure to silver or gold metal surfaces without the use of additional
protective coatings of nanomaterials. Here, novel rhodamine “dimers”
and “trimers” have been created that demonstrate a higher
avidity for metal nanoparticles and induce aggregation to create plasmonic
“hotspots” as indicated by enhanced Raman scattering in situ. These aggregates can be formed in a colloid, on
surfaces, or membrane substrates such as poly­(vinylidene fluoride)
for applications in biosciences. The integrity of the materials and
Raman signals are maintained for months of time on different substrates.
These dye materials should provide avenues for simplified in situ generation of sensors for Raman-based assays especially
in settings requiring highly robust performance.