Kinetically-Controlled Growth of Chestnut-Like Au Nanocrystals with High-Density Tips and Their High SERS Performances on Organochlorine Pesticides

Abstract

A modified seed growth route was developed to fabricate the Au nanocrystals with high-density tips based on kinetically-controlled growth via adjusting the adding rate of Au seeds into growth solution. The obtained Au nanostructures were chestnut-like in morphology and about 100 nm in size. They were built of the radial [111]-oriented nanoneedles and were 30–50 nm in length. There were about 120–150 tips in each nanocrystal. The formation of chestnut-like Au nanocrystals is ascribed to surfactant-induced preferential growth of seeds along direction [111]. Importantly, the chestnut-like Au configuration displayed powerful surface enhanced Raman scattering (SERS) performance (enhance factor > 107), owing to the high density of tips. Further, such film was used as a SERS substrate for the detection of lindane (γ-666) molecules (the typical organochlorine pesticide). The detection limit was about 10 ppb, and the relationship between SERS intensity I and concentration C of 666 accords with the double logarithm linear. This work presents a simple approach to Au nanocrystal with high-density tips, and provides a highly efficacious SERS-substrate for quantitative and trace recognition of toxic chlorinated pesticides.

Highly reusable nanoporous silver sheet for sensitive SERS detection of pesticides

“…This visible limit of detection 55,56 of lindane is comparable to previous studies. 7,14,16 The NPAg sheet is suitable for sensitive SERS detection of organochlorine pesticides, since there is no background peak in the organochloride characteristic region (300-400 cm −1 ). Moreover, the NPAg sheet after one-month bare storage under ambient conditions still demonstrates identical SERS enhancement in the detection of lindane to the newly prepared NPAg sheet (ESI, Fig.…”

“…The SERS phenomena rely on various nanostructured substrates to induce localized surface plasmon resonance for electromagnetic enhancement. [11][12][13] To improve SERS performance, various strategies have been reported to optimize the component, 14,15 shape, 16,17 size, 18 architecture, 19,20 and interfacial functionalization 7 of nanoparticle-based SERS substrates. This optimization constructs effective hot spots to capture analytes with up to 10 14 -10 15 signal enhancement, reaching single-molecule detection.…”

Strategies for SERS Detection of Organochlorine Pesticides

“…Next, the colloidal nanostructures were dropped on silicon and dried, creating a ~500 nm thick film ( Figure 2 B) with even better SERS performances. Tested on lindane, a limit of detection (LOD) of 10 ppb could be achieved [ 19 ].…”

“…( B ) ( a ) FESEM image of the chestnut-like Au nanocrystal film, ( b ) local magnified image. Reproduced with permission of [ 19 ]. ( C ) ( a – c ) SEM images of F-NPs substrate with 100 nm of Ag coating film.…”

“…This can be achieved by increasing the substrate’s performance by increasing the affinity of the analyte for the substrate or by preconcentration. Strategies like concentrating nanoparticles through mechanical traps [ 18 ], inducing hot-spots by aggregation or assembly of nanostructures [ 19 ] in different-sized oligomers, films, or film patches [ 20 ] are all improving the sensitivity of the substrate. Such approaches may even enable the detection of molecules with low affinities toward the metal substrate.…”