Lab-On-Capillary Platform for On-Site Quantitative SERS Analysis of Surface Contaminants Based on Au@4-MBA@Ag Core–Shell Nanorods

Abstract

A portable and highly reproducible lab-on-capillary surface-enhanced Raman scattering (SERS) platform was developed using a specially designed homemade device for rapid on-site SERS measurement. In particular, this platform was composed of a capillary with a tiny orifice, which allows an effective and lossless sample extraction, resulting in high SERS performance. The capillary-based plasmonic substrate was prepared by compactly assembling Au@Ag core–shell nanorods (NRs) embedded with the 4-mercaptobenzoic acid (4-MBA) molecule as an internal standard onto the inner wall of a capillary tube. The fabrication process is facile and convenient with no requirement for complicated procedures. The exclusively prepared nanoparticles were able to significantly improve the signal consistency and overcome the limitations of reliable quantitative SERS analysis compared with conventional methods. Importantly, it was found that this capillary-based substrate with higher sensitivity was essentially attributed to more valid nanoparticles in the effective laser excitation region derived from the unique structure of the capillary. Furthermore, the applicability of the Au@4-MBA@Ag nanorod-decorated capillary for the quantitative identification of fungicides (malachite green and crystal violet) on the shell was demonstrated. As a result, this proposed lab-on-capillary sensor holds promising practical potential for rapid on-site analysis, especially for various contaminants on an uneven surface.

From Dilute to Multiple Layers: Bottom‐Up Self‐Assembly of Rough Gold Nanorods as SERS Platform for Quantitative Detection of Thiram in Soil

“…Each Au nanostructure was prepared through the seed‐medicated growth approach in aqueous solution at room temperature, [ 44,58,59 ] as illustrated in Figure a. First, pentatwinned Au nanojavelins with average width of 30 nm and length of 164 nm were synthesized using thermally treated seeds (Figure 2c1,c2).…”

“…The sub‐monolayer film of Au NPs was prepared by electrostatic interaction. [ 59 ] In brief, the CTAC‐stabilized Au NPs were transferred to PVP‐coated colloid, and then re‐dispersed in ethanol. In addition, Si wafers were immersed in the piranha solution (H 2 SO 4 :H 2 O 2 = 7:3), followed by rinsing with deionized water and dried.…”

Flexible Hybrid Sensor Systems with Feedback Functions

“…The swab sampling (i.e., the paste and peel off) strategy relies on the collection and adsorption of analytes on the substrate and then performs onsite measurements (Figure 9h). [ 297–300 ] The in situ measurement approach is based on conformally attaching the flexible and transparent SERS chips to object of interest and then collecting the SERS signals directly (Figure 9i). [ 301–305 ] Both detection routes promise their extensive applications in healthcare, environmental monitoring, and food safety detection.…”

Electrostatic self-assembly of 2D Janus PS@Au nanoraspberry photonic-crystal array with enhanced near-infrared SERS activity

“…While the use of visible-wavelength laser has some limitations, such as a short penetration depth in tissues, and the signal overwhelmed by fluorescent background. 24 To compensate for these shortcomings, more and more attention has been focusing on tuning the LSPR position of noble-metal nanostructures into near-infrared (NIR) region that can realize a NIR-SERS activity, such as tuning the nanostructures into anisotropic nanorod 25 , nanostar 26,27 , nanoshell, or porosity [28][29][30] . Although these nanostructures demonstrate a well-performed NIR-SERS property, their SERS enhancement factors (EF) still need to be improved due to the low density of 'hotspots' generated in these discrete nanostructures.…”