Abstract
The high reproducibility of trace detection in complex systems is very hard but crucial to analytical technology and science. Here, we present a surface-enhanced Raman scattering (SERS) platform made by large-scale self-assembly of Au nanoparticle (NP) arrays at the cyclohexane/water interface and its use for pesticides residues trace detection. The analyte molecules spontaneously localize into the Au NPs’ nanogaps during the self-assembly process, yielding excellent Raman signal enhancement by surface effects, and possibly both by the concentration of the analytes into the array and by plasmonic hot-spot formation. Transmission electron microscopy (TEM) images demonstrate a good uniformity of interparticle distances (2–3 nm) in the Au NP arrays. SERS experiments on crystal violet (CV) molecules demonstrated that the relative standard deviations (RSD) of the band intensities at 1173, 1376, and 1618 cm−1 were 6.3%, 6.4%, and 6.9%, respectively, indicating high reproducibility of the substrate. Furthermore, we demonstrate that two pesticides dissolved in organic and aqueous phases could be simultaneously detected, suggesting an excellent selectivity and universality of this method for multiplex detection. Our SERS platform opens vast possibilities for repeatability and sensitivity detection of targets in various complex fields.
Highlights
Molecular detection of target analytes such as pesticides [1], drugs [2], pharmaceutical molecules [3], biochemicals [4], neurotransmitters [5], and explosives [6] is urgently needed in many fields
The surface-enhanced Raman scattering (SERS) technique demonstrates a huge advantage with regard to this problem because of the high sensitivity and unique vibrational fingerprints [9,10,11]
Au NPs were synthesized according to the citrate reduction method
Summary
Molecular detection of target analytes such as pesticides [1], drugs [2], pharmaceutical molecules [3], biochemicals [4], neurotransmitters [5], and explosives [6] is urgently needed in many fields. The surface-enhanced Raman scattering (SERS) technique demonstrates a huge advantage with regard to this problem because of the high sensitivity and unique vibrational fingerprints [9,10,11]. SERS spectra with a narrow linewidth show promise in multiple detection under the complex fluids, including detection down to the single molecule level [12,13]. The enhancement of the Raman signal depends on the exciting localized surface plasmons within metallic substrates [14]. The design of a metallic substrate with a high density of hotspots can lead to a stronger signal, thereby lowering the limits of detection (LOD). The protecting and capping agents in the precise nanofabrication will prevent analytes from reaching the nanogaps of the substrates and decrease the SERS sensitivity. Precise nanofabrication is costly, non-scalable, and hard to clean
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