Highly uniform and reproducible surface-enhanced Raman scattering from DNA-tailorable nanoparticles with 1-nm interior gap

Abstract

An ideal surface-enhanced Raman scattering (SERS) nanostructure for sensing and imaging applications should induce a high signal enhancement, generate a reproducible and uniform response, and should be easy to synthesize. Many SERS-active nanostructures have been investigated, but they suffer from poor reproducibility of the SERS-active sites, and the wide distribution of their enhancement factor values results in an unquantifiable SERS signal. Here, we show that DNA on gold nanoparticles facilitates the formation of well-defined gold nanobridged nanogap particles (Au-NNP) that generate a highly stable and reproducible SERS signal. The uniform and hollow gap (∼1 nm) between the gold core and gold shell can be precisely loaded with a quantifiable amount of Raman dyes. SERS signals generated by Au-NNPs showed a linear dependence on probe concentration (R(2) > 0.98) and were sensitive down to 10 fM concentrations. Single-particle nano-Raman mapping analysis revealed that >90% of Au-NNPs had enhancement factors greater than 1.0 × 10(8), which is sufficient for single-molecule detection, and the values were narrowly distributed between 1.0 × 10(8) and 5.0 × 10(9).

Ultrasensitive surface-enhanced Raman scattering detection in common fluids

“…Among various analytical techniques, surface-enhanced Raman scattering (SERS) is among the most promising methods in detecting trace amounts of molecules owing to its high molecular specificity (i.e., differentiation between different types of molecules) and high sensitivity (i.e., the lowest analyte concentration from which SERS signals are distinguishable from the noise signal of a control sample) (9)(10)(11)(12)(13)(14)(15)(16)(17). Extensive studies have focused on the structural optimization of the SERS substrate to improve SERS sensitivity (18)(19)(20)(21)(22), but there are two important roadblocks that limit its practical applications. First, SERS detection in liquid media relies on highly statistical binding of analytes to the SERS-sensitive regions (or "hot spots"), a consequence of the diffusive nature of the analytes (23)(24)(25)(26)(27).…”

Clicking DNA to gold nanoparticles: poly-adenine-mediated formation of monovalent DNA-gold nanoparticle conjugates with nearly quantitative yield

“…[14][15][16] In addition, because we have obtained high yields of well-defined and uniform Au nanostructures, we expect that this system holds great promise for DNAregulated plasmonic applications 42,43 and biomolecular imaging. [44][45][46][47] …”

Radionuclide-embedded gold nanoparticles for enhanced dendritic cell-based cancer immunotherapy, sensitive and quantitative tracking of dendritic cells with PET and Cerenkov luminescence

“…4,23,24 In this study, we focused on the chemical functionality of the oligonucleotide base on the AuNPs that can be used as a reaction site for radiolabeling. The primary amine group in the adenine base can be functionalized with sulfo-SHPP, leading to the formation of an amide bond between the 4-hydroxy phenyl group and primary amine in adenine (Supplementary Figure S1).…”

“…An additional Au shell formation reaction was performed to produce the RIe-AuNPs using our previously reported procedures. 4 We used 125 I to characterize the stability of the RIe-AuNPs, and 124 I was selected for combined PET and CLI imaging. The UV-visible spectra of the SHPP-A 10 -AuNPs and the RI-AuNPs were identical to that of the A 10 -AuNPs, as shown in Figure 1b, indicating that no significant particle aggregation occurred during the radionuclide labeling reaction.…”

“…Therefore, simple, straightforward labeling chemistry that can produce sensitive imaging agents and robust protection methods have been intensively sought. [4][5][6][7] Non-covalent conjugation of 125 I on AuNPs resulted in a low loading of radio-isotopes per particle (only six iodines per particle) and release of the radio-isotope from the AuNP surface was also significant in spite of the presence of a protective layer composed of a polymer (that is, PEG), which necessitated the injection of a high dose (10 mg kg − 1 ) of the imaging agent. 8 Although the signal sensitivity and stability of bioimaging agents are critical issues for all molecular imaging modalities, in the field of dendritic cell (DC)-based cancer immunotherapy, achieving sensitive tracking of the migration of bone marrow-derived DCs to vascular and lymphatic systems is especially important for accurately evaluating the outcomes of DC-based immunotherapy.…”