Magnetoelectrically Enhanced Molecular Recognition on Plasmonic Surfaces

Herein, we introduce a magnetoelectrically induced surface-enhanced Raman signal amplification (MIERS) method using an engineered plasmonic nanocomposite comprising a magnetostrictive nanorod embedded within a hollow piezoelectric nanosphere and silver nanoparticles (AgNPs). This intricate design facilitates magnetoelectrically mediated injection of free charge carriers, thereby increasing the overall plasma frequency and enabling charge transfer to analyte molecules, thereby enhancing SERS response. The unique core-shell architecture further reduces the recombination rate of charge carriers of opposite polarity, thereby prolonging the lifetime of the generated electrons, which diffuse toward the attached plasmonic AgNPs. State-of-the-art in-situ atomic force microscopy measurements on a single magnetoelectric (ME) nanostructure under magnetic field excitation (MFE ≈ 140 mT) revealed highly localized surface charge carrier generation with peak ME voltage generation of ∼640 mV, which has never been reported earlier. Remarkably, MIERS enabled the detection of Raman markers and biomolecules down to nanomolar concentrations under an MFE of approximately 80 mT, demonstrating its ultrasensitive detection capability. By magnetoelectrically actuating SERS, MIERS also has the potential to enable molecular recognition through the enhancement of specific vibrational modes and, hence, to establish a unique, versatile platform for SERS enhancement in precise analytical and biomedical applications.