Application of Resonant Plasmonic Bowtie Nanoantennas for Optically-Assisted Diffusiophoretic Trapping of Extracellular Vesicles and Nanoparticles.

Plasmonic antennas leveraging localized surface plasmon resonances (LSPR) hold significant premise for efficiently trapping nanoscale particles at low power levels. However, their effectiveness is hindered by photothermal effects that arise with metallic nanoparticles, leading to decreased stability of trapped particles. To address this limitation, a hybrid approach that combines depletion attraction and photothermal effects inherent in plasmonic structures is proposed, capitalizing on thermally induced concentration gradients. Through the thermophoretic depletion of polyethylene glycol (PEG) molecules around plasmonic hotspots, sharp concentration gradients are created, enabling precise localization of nanoscopic particles through a synergistic effect with diffusiophoretic forces. The experiments conducted in this study successfully demonstrate the ability to trap and dynamically manipulate small extracellular vesicles and 100 nm polystyrene beads, showcasing the platform's potential for assembly at the nanoscale. Remarkably, this method maintains stable trapping performance even at a laser power of 0.78