Plasmonic Nanotrenches\nwith 1 nm Nanogaps for Surface-Enhanced\nRaman Scattering-Based Screening of His-Tagged Proteins

This study represents a highly sensitive\nand selective\napproach\nto protein screening using surface-enhanced Raman scattering (SERS)\nfacilitated by octahedral Au nanotrenches (OANTs). OANTs are a novel\nclass of nanoparticles characterized by narrow, trench-like excavations\nindented into the eight facets of a Au octahedron. This unique configuration\nmaximizes electromagnetic near-field focusing as the gap distance\ndecreases to ∼1 nm. Owing to geometrical characteristics of\nthe OANTs, near-field focusing can be maximized through the confinement\nand reflectance of light trapped within the trenches. We used Ni ions\nand molecular linkers to confer selective binding affinity for His-tagged\nproteins on the surfaces of the OANTs for SERS-based protein screening.\nRemarkably, SERS-based protein screening with the surface-modified\nOANTs yielded outstanding screening capabilities: 100% sensitivity\nand 100% selectivity in distinguishing His-tagged human serum albumin\n(HSA) from native HSA. This highlights the significantly enhanced\nprotein screening capabilities achieved through the synergistic combination\nof SERS and the OANTs.