A facile temperature regulation strategy is developed for fabrication of Au concave nanocrystals with specific shapes via seed-assisted growth at 25 °C or lower. It has been found that the reaction temperature, even with minor changes, can significantly influence the shape of the nanocrystals, which evolves from the concave trisoctahedral to calyptriform, coral and dendritic structures with the decrease of temperature from 25 °C to 5 °C. The size and optical absorbance spectra of the nanocrystals can be determined just by the addition amount of Au seeds. The formation of the Au concave nanocrystals is attributed to the preferential growth of the nuclei in 〈110〉 and 〈111〉 directions, along which the growth rates are of different temperature dependences. Importantly, the concave trisoctahedral and calyptriform Au nanocrystal-built films have exhibited strong surface enhanced Raman scattering (SERS) activity towards the lindane molecules, with the enhancement factor higher than 107, due to their high density of sharp corners/edges or the tip effect. The Raman peak intensity versus lindane concentration is subject to a linear double logarithmic relation from 30 ppb to 300 ppm, which is attributed to the Freundlich adsorption of lindane molecules on the Au nanocrystals. This work provides not only a simple route for the fabrication of the Au nanocrystals with various specific structures but also efficient SERS substrates for trace detection of organochlorine pesticide residues.

Silver nanoplate hierarchical turreted ordered arrays were fabricated through an electro-deposition method on ordered acuate silicon nanocone templates. Such arrays can be used as SERS substrates for trace analyses of streptomycin sulphate, and exhibit high activity and stability. This work is of importance in practical applications based on the SERS effect of noble metal micro/nano-structured arrays.

Au opening-nanoshell ordered arrays with tunable local surface plasmon resonance (SPR) property have been fabricated based on sputtering deposition onto monolayer colloidal crystal. The changes in local SPR peak for the arrays can be well tuned from visible to near-infrared region with decreasing of the spacing between two neighbor opening-nanoshells. It has been revealed that the changes of SPR peak originate from the electromagnetic coupling between two adjacent Au opening-nanoshells. This study is important to design and fabricate surface-enhanced Raman scattering substrates with high activity and practical application.Keywords: Au opening-nanoshell; electromagnetic Coupling; ordered arrays; SERS; sputtering deposition; tunable SPR;

•A strategy for SERS-based ultrasensitive detection of sarin-simulant is presented.•Surface-modified SERS substrate can preferentially capture the sarin-simulant agent.•Raman peak intensity shows a linear double logarithmic relation with simulant content.•Such linear relation arises from Freundlich adsorption of simulant on the substrate.•The limit of detection for sarin-simulant agent is down to about 1 ppb.Highly efficient detection of the organicphosphor nerve agents such as sarin and soman, based on surface enhanced Raman scattering (SERS) effect, has been in challenge due to their weak adsorption property on coin metals. In this paper, a new strategy is presented to achieve the SERS-based ultrasensitive detection of sarin-simulated agent methanephosphonic acid (MPA) via the surface modification of SERS-substrates. The Au-coated Si nanocone array is surface-modified with 2-aminoethanethiol and used as SERS-substrate for detection of MPA. It has been shown that the modified substrate could preferentially capture MPA molecules in the solution with coupling agent and induce amidation reaction. The reaction products are still bound or anchor on the substrate’s surface. The MPA molecules can thus be detected by Raman spectral measurement of the solution-soaked SERS-substrate. The minimum detection level is down to ∼1 ppb. The Raman peak intensity versus the MPA concentration is subject to a linear double logarithmic relation from ∼1 ppb to ∼1000 ppm, which is attributed to Freundlich adsorption of MPA on the surface-modified SERS substrate. This study provides a new way for the highly efficient SERS-based detection of the organophosphorus nerve agents and some other target molecules weakly interacted with metal substrates.A strategy is presented to achieve the SERS-based ultrasensitive detection of organic-phosphor nerve agent sarin (simulant) via surface modification of the Au SERS-substrate, demonstrating a linear double logarithmic relation between the Raman peak intensity and the simulant concentration in the range from 1 ppb to 1000 ppm.Download full-size image

Silver nanoplate hierarchical turreted ordered arrays were fabricated through an electro-deposition method on ordered acuate silicon nanocone templates. Such arrays can be used as SERS substrates for trace analyses of streptomycin sulphate, and exhibit high activity and stability. This work is of importance in practical applications based on the SERS effect of noble metal micro/nano-structured arrays.