Engineering 3D Multi-Branched Nanostructures for Ultra- Sensing Applications

The fabrication of plasmonic nanostructures with sub-10 nm gaps supporting extremely large electric field enhancement (hot-spot) has attained great interest over the past years, especially in ultra-sensing applications. The “hot-spot” concept has been successfully implemented in surface-enhanced Raman spectroscopy (SERS) through the extensive exploitation of localized surface plasmon resonances. However, the detection of analyte molecules at ultra-low concentrations, i.e., down to the single/few molecule level, still remains an open challenge due to the poor localization of analyte molecules onto the hot-spot region. On the other hand, three-dimensional nanostructures with multiple branches have been recently introduced, demonstrating breakthrough performances in hot-spot-mediated ultra-sensitive detection. Multi-branched nanostructures support high hot-spot densities with large electromagnetic (EM) fields at the interparticle separations and sharp edges, and exhibit excellent uniformity and morphological homogeneity, thus allowing for unprecedented reproducibility in the SERS signals. 3D multi-branched nanostructures with various configurations are engineered for high hot-spot density SERS substrates, showing an enhancement factor of 1011 with a low detection limit of 1 fM. In this view, multi-branched nanostructures assume enormous importance in analyte detection at ultra-low concentrations, where the superior hot-spot density can promote the identification of probe molecules with increased contrast and spatial resolution

Hot-Spot Engineering in 3D Multi-Branched Nanostructures:Ultrasensitive Substrates for Surface-Enhanced Raman Spectroscopy

The detection of probe molecules at ultralow concentrations, even at the single-molecule level, can be addressed with the breakthrough concept of plasmonic hot-spot engineering. In view of that, the fabrication of nanostructures endowed with sub-10 nm gaps and extremely large near-field enhancement has gained increasing attention, becoming a key-condition for improved sensitivity. The present work demonstrates a new perspective in ultrasensitive detection by engineering every individual plasmonic nanostructure with a giant electric field confinement and superior hot-spot densities, thus eliminating the need for extremely narrow inter-particle separations

Plasmon based biosensor for distinguishing different peptides mutation states

Periodic and reproducible gold nanocuboids with various matrix dimensions and with different inter-particle gaps were fabricated by means of top-down technique. Rhodamine 6G was used as a probe molecule to optimize the design and the fabrication of the cuboid nanostructures. The electric field distribution for the nanocuboids with varying matrix dimensions/inter-particle gap was also investigated. These SERS devices were employed as biosensors through the investigation of both myoglobin and wild/mutated peptides. The results demonstrate the probing and the screening of wild/mutated BRCA1 peptides, thus opening a path for the fabrication of simple and cheap SERS device capable of early detection of several diseases