Bilayered Raman‐Intense Gold Nanostructures with Hidden Tags (BRIGHTs) for High‐Resolution Bioimaging

Abstract

Conventional SERS probes suffer from limited brightness and poor reproducibility and stability making them unsuitable for routine in vivo applications. A novel class of layered SERS probes is demonstrated in which individual nanostructures host electromagnetic hotspots, thus increasing brightness by more than two orders magnitude compared to conventional individual nanostructures.

Nanooptics of Plasmonic Nanomatryoshkas: Shrinking the Size of a Core–Shell Junction to Subnanometer

“…Such NMs were synthesized in a layer-by-layer process, starting with the preparation of 20 nm diameter Au cores. 37 A self-assembled monolayer of 1,4-BDT molecules was formed to replace the original capping agent of cetyltrimethylammonium chloride (CTAC) on the surface of Au cores. After the removal of the excess 1,4-BDT molecules, a Au shell of desired thickness is grown on the cores by adding HAuCl 4 , CTAC (as a capping agent) and ascorbic acid (as a mild reducing agent).…”

“…(E) Simulated electric field intensity (log|E/E 0 |) distributions (top) and surface charge distributions (bottom) at resonance corresponding to the modes 1−6, using classical electromagnetic theory. The SEM image in (B) and the measured extinction spectrum in (C) for the NM (ii) were reproduced from ref 37 for comparison between the NMs with different gap sizes.…”

“…30−35 For a NM with core−shell separations below 0.4 nm, calculations from time-dependent density functional theory (TDDFT) have predicted pronounced tunneling across the nanogap, which significantly modifies the absorption cross-section and the local electric field enhancements. 22 More importantly, advances in the synthesis of NMs with precise and uniform subnanometer gaps provide a better platform for experimental investigation of quantum plasmonic effects, 17,25,36,37 compared to typical nanoparticle dimer structures fabricated by various state-of-the-art techniques including high-resolution electron-beam lithography, 30 electron-beam induced manipulation, 26 dual AFM tip approaching, 28 and dropcasting. 27,31 In this Letter, we present a comprehensive investigation of the optical properties of NMs with different nanogap widths ranging from 100 nm down to the subnanometer regime.…”

Reporter-Embedded SERS Tags from Gold Nanorod Seeds: Selective Immobilization of Reporter Molecules at the Tip of Nanorods

“…One is to directly deposit Ag or Au shells on seed NPs functionalized with small thiol molecules. 5,11 The other is to form nanomatryoshka structures in which an insulation matrix layer (such as DNA, 7,8,12−15 polymer, 6 and dithiol molecules 4,16,17 ) with Raman-active parts is applied to modify the seed NPs before outer shell growth. In most RE tags, gold nanospheres (NSs) or nanostars are selected as seed NPs.…”

Gold Nanosensitisers for Multimodal Optical Diagnostic Imaging and Therapy of Cancer

“…Various biopolymers have been reported as stabilisers, but polyethylene glycol (PEG) and bovine serum albumin (BSA) have been recently exploited for their enhanced biocompatibility [9,28]. PEG covering has been shown to stabilise gold nanoparticles and shield the Raman reporter due to the specific adherence on gold nanoparticle's surface that spontaneously forms a monolayer on gold [29]. BSA, in its denatured form, was found to be more advantageous in that its thiol binding capacity was found to be much stronger and maintained the non-aggregated isolated state of the nanostructures even after multiple washes.…”