Strong Magneto-Optical Response of Nonmagnetic Organic Materials Coupled to Plasmonic Nanostructures.
Plasmonic nanoparticles (PNPs) can significantly modify the optical properties of nearby organic molecules and thus present an attractive opportunity for sensing applications. However, the utilization of PNPs in conventional absorption, fluorescence, or Raman spectroscopy techniques is often ineffective due to strong absorption background and light scattering, particularly in the case of turbid solutions, cell suspensions, and biological tissues. Here we show that nonmagnetic organic molecules may exhibit magneto-optical response due to binding to a PNP. Specifically, we detect strong magnetic circular dichroism signal from supramolecular J-aggregates, a representative organic dye, upon binding to silver-coated gold nanorods. We explain this effect by strong coupling between the J-aggregate exciton and the nanoparticle plasmon, leading to the formation of a hybrid state in which the exciton effectively acquires magnetic properties from the plasmon. Our findings are fully corroborated by theoretical modeling and constitute a novel magnetic method for chemo- and biosensing, which (upon adequate PNP functionalization) is intrinsically insensitive to the organic background and thus offers a significant advantage over conventional spectroscopy techniques.
CIC NanoGUNE , Avenida Tolosa 76, 20018 Donostia-San Sebastián, Spain.|National University of Ireland Galway , University Road, Galway, Ireland.
Dzmitry
0000-0002-6588-8122
D
Melnikau
CIC NanoGUNE , Avenida Tolosa 76, 20018 Donostia-San Sebastián, Spain.
Alexander A
AA
Govyadinov
CIC biomaGUNE , Paseo de Miramón 182, 20014 Donostia-San Sebastián, Spain.
Ana
A
Sánchez-Iglesias
CIC biomaGUNE , Paseo de Miramón 182, 20014 Donostia-San Sebastián, Spain.|IKERBASQUE, Basque Foundation for Science , 48013, Bilbao, Spain.
Marek
0000-0002-3458-8450
M
Grzelczak
CIC biomaGUNE , Paseo de Miramón 182, 20014 Donostia-San Sebastián, Spain.|IKERBASQUE, Basque Foundation for Science , 48013, Bilbao, Spain.|Biomedical Research Networking Center in Bioengineering Biomaterials and Nanomedicine, Ciber-BBN , Paseo de Miramón 182, 20014 Donostia-San Sebastián, Spain.
Luis M
0000-0002-6647-1353
LM
Liz-Marzán
Centro de Física de Materiales (MPC, CSIC-UPV/EHU) Paseo Manuel de Lardizabal 5, Donostia-San Sebastián, 20018, Spain.|Donostia International Physics Center (DIPC) , Paseo Manuel de Lardizabal 4, Donostia-San Sebastián, 20018, Spain.|IKERBASQUE, Basque Foundation for Science , 48013, Bilbao, Spain.
Yury P
YP
Rakovich
J-aggregates; Sensing; magneto-optical activity; magneto-plasmonics; plexciton; strong coupling