Abstract
In this work, a simple and versatile SERS sensing platform enabled by AuNPs-analyte/AuNPs double-decker structure on wax-coated hydrophobic surface was developed using a portable Raman spectrometer. Wax-coated silicon wafer served as a hydrophobic surface to induce both aggregation and concentration of aqueous phase AuNPs mixed with analyte of interest. After drying, another layer of AuNPs was drop-cast onto the layer of AuNPs-analyte on the substrate to form double-decker structure, thus introducing more “hot spots” to further enhance the Raman signal. To validate the sensing platform, methyl parathion (pesticide), and melamine (a nitrogen-enrich compound illegally added to food products to increase their apparent protein content) were employed as two model compounds for trace sensing demonstration. The as-fabricated sensor showed high reproducibility and sensitivity toward both methyl parathion and melamine detection with the limit of detection at the nanomolar and sub-nanomolar concentration level, respectively. In addition, remarkable recoveries for methyl parathion spiked into lake water samples were obtained, while reasonably good recoveries for melamine spiked into milk samples were achieved. These results demonstrate that the as-developed SERS sensing platform holds great promise in detecting trace amount of hazardous chemicals for food safety and environment protection.
Highlights
Surface enhanced Raman scattering (SERS) has been drawing increasing attention in the field of analytical chemistry and life science since its first introduction about 40 years ago (Fleischmann et al, 1974; Albrecht and Creighton, 1977; Jeanmaire and Duyne, 1977; Freeman et al, 1995; Wang et al, 2013; Zhou et al, 2016)
SERS-Based Trace Sensing field enhancement enabled by localized surface plasmon resonance (LSPR) “hot spots,” which are typically formed at small gaps between noble metal nanoparticles, with an enhancement factor up to 1012 (Kleinman et al, 2013)
We present a simple and versatile SERS sensing platform enabled by AuNPs-analyte/AuNPs doubledecker structure on wax-coated hydrophobic surface using a portable Raman spectrometer
Summary
Surface enhanced Raman scattering (SERS) has been drawing increasing attention in the field of analytical chemistry and life science since its first introduction about 40 years ago (Fleischmann et al, 1974; Albrecht and Creighton, 1977; Jeanmaire and Duyne, 1977; Freeman et al, 1995; Wang et al, 2013; Zhou et al, 2016). Compared with traditional bulky instruments, for instance gas chromatography (Vesely et al, 2003), liquid chromatography (Hogard et al, 2017), high-performance liquid chromatography (Özyürek et al, 2012) etc., SERS based detection can be realized using a portable Raman spectrometer, which displays several advantages, such as portability, easy accessibility, cost effectiveness, and rapid analysis. These advantages endow its potential use in point-of-care and in-field trace sensing applications. Acceptable sensitivity and reproducibility have been obtained for melamine detection in aqueous solution, more sensitive detection for hazardous chemicals is still highly demanded, especially for the detection of highly toxic compounds such as pesticides
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