[en] Highlights: • Atomically precise Ag₁₅₂ nanoclusters (~2 nm) are introduced into 3D arrays structure. • Au nanoparticle (AuNP) with single particle size are prepared as AuNP monolayer film. • The ZnO-NC/Au/Ag₁₅₂ 3D SERS substrate has high density of hot spots. • The ZnO-NC/Au/Ag₁₅₂ substrate exhibits the capability of ultra-sensitive detection. • The substrate can achieve rapid self-cleaning and recycling through photocatalysis. It is well known that the intensity and density of hot spots directly determine the surface-enhanced Raman scattering (SERS) performance of a substrate. In this work, we proposed a new strategy to improve the density of hot spots of a SERS substrate by innovatively introducing atomically precise Ag nanoclusters (Ag₁₅₂(SCH₂CH₂Ph)₆₀, ~2 nm). First, a 30 nm gold nanoparticle (AuNP) film in conjunction with hexagonal zinc oxide nanocone (ZnO-NC) arrays is prepared as a three-dimensional (3D) backbone; these ZnO-NC/AuNP arrays provide numerous anchors to facilitate the loading of Ag₁₅₂ nanoclusters, thereby further enhancing the intensity and density of hot spots on the entire substrate. In addition, the ultra-small particle size of the Ag₁₅₂ nanoclusters will not cover the original hot spots on the surface of AuNP film during deposition. Thus, the ZnO-NC/Au/Ag₁₅₂ 3D SERS sensing platform shows the capability of ultra-sensitive detection, and the substrate results in an enhancement factor (EF) of up to 6.48 × 10⁹. More importantly, the prepared substrate can act as an environmentally friendly sensing platform to achieve rapid self-cleaning and recycling through photocatalysis. The present work confirms the application prospects of novel metal nanoclusters in the field of SERS and photocatalysis.

[en] It is known that the intensity of surface-enhanced Raman scattering (SERS) of monomeric gold nanoparticles (GNPs) is insufficient for ultrasensitive analysis. The authors describe dimeric GNPs for use in a competitive SERS and aptamer based assay for thrombin. The reagent 1,2-bis(4-pyridyl) ethylene serves as both the coupling agent and the Raman reporter on the GNP dimers. In the presence of thrombin, the hybridization of two aptamers, one attached to the GNP dimers, the other to magnetic nanoparticles, is competitively prevented. This method takes advantage of the unique “hot spots” of the GNP dimers to amplify the Raman signal. This results in an ultra-sensitive thrombin assay when compared to assays using GNP monomers. The limit of detection is as low as 1 fM of thrombin. The Raman intensity, best measured at 1612 cm⁻¹, increases linearly in the 1 fM to 10 nM thrombin concentration range. The method was applied to the determinaiton of thrombin in spiked simulated body fluid and human serum.

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[en] The authors report on a surface-enhanced Raman scattering (SERS) nanoprobe for the specific detection of Escherichia coli O157:H7 (E. coli O157:H7). Gold nanoparticles (AuNPs) were coated with a thick silica shell, and the Raman reporter (4,4′-dipyridyl) was embedded between gold nanoparticle and silica shell. This technique prevents any external effects on the AuNPs from the environment and avoids any interaction between the Raman reporter and possible impurities. Compared to the SERS nanoprobe of the conventional AuNP/AgNP type, the present nanoprobe can be applied in complex biochemical circumstances without aggregation because of its excellent stability. The SERS nanoprobeis stable for up to 50 h. The probe was applied to the SERS detection of E. coli O157:H7 by exploiting the Raman band peaking at 1612 cm⁻¹ of 4,4′-dipyridyl (DP). The limit of detection is as low as 10 CFU·mL⁻¹. The technique was successfully employed to the detection of E. coli O157:H7 in real samples, achieving recoveries between 95.5 and 114.8%. .

[en] A surface-enhanced Raman scattering (SERS) method is described for the determination of microRNA that is associated with various forms of cancer. The substrate consists of functionalized gold-silver bimetallic structure, and the sensitivity is strongly enhanced by making use of a re-circulated enzymatic amplification system (REAS). Poly-dopamine acts as both a reductant and a protective of the substrates. It was employed to link the gold core and silver satellite. The unique “hot spots” consisting of a Au@PDA@Ag nanocomposite improve the Raman signal and sensitivity. The reductive feature of PDA can prevent the susceptible oxidation of metallic silver to maintain the high Raman activity. To improve the sensitivity of the assays, a re-circulated enzymatic amplification system was developed in which the nicking endonuclease triggers the nucleic acid reaction system to enter an amplified cycle. By integrating the bimetallic nanosubstrate and magnetic separation into the REAS, microRNA can be detected by SERS (best at the Raman band of 1586 cm⁻¹) with a limit of detection as low as 0.2 fM. In our perception, the assay provides an exciting new avenue to study the expression of tumor genes. Thus, it holds vast promise in cancer diagnosis.

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[en] Highlights: • Comprehensive analysis of available rotation-vibration data • High-accuracy measurements of pure rotational transitions within 4 states • High accuracy line list presented. Published high-resolution rotation-vibration transitions of H${}_2^{12}$C${}^{16}$O, the principal isotopologue of methanal, are analyzed using the MARVEL (Measured Active Rotation-Vibration Energy Levels) procedure. The literature results are augmented by new, high-accuracy measurements of pure rotational transitions within the ground, ${\nu }_3,$ ${\nu }_4,$ and ${\nu }_6$ vibrational states. Of the 16 596 non-redundant transitions processed, which come from 43 sources including the present work, 16 403 could be validated, providing 5029 empirical energy levels of H${}_2^{12}$C${}^{16}$O with statistically well-defined uncertainties. All the empirical rotational-vibrational energy levels determined are used to improve the accuracy of ExoMol’s AYTY line list for hot formaldehyde. The complete list of collated experimental transitions, the empirical energy levels determined, as well as the extended and improved line list are provided as Supplementary Material.