Multi-spiked silver stars for ultrasensitive and multiplexed SERS detection of analytes

Abstract

We report a facile synthesis procedure of multi-spiked star-shaped silver structures with sharp morphological features and broad plasmonic absorption for the fabrication of surface-enhanced Raman scattering (SERS) substrates. The multi-branched morphology of silver stars (AgSs) provides copious hot spots on SERS-active substrates to detect ultra-low concentrations of probe molecules. Significant Raman intensity enhancement factors of the order of ∼10 9 were obtained for the different analytes. The AgSs-based SERS-substrates show ultra-sensitive SERS performance for the detection of probe molecules rhodamine B, methylene blue, thiram, and phosmet with detectabilities 2.6 × 10 −16 , 1.97 × 10 −17 , 1.78 × 10 −18 , and 4.08 × 10 −14 M concentration, respectively. The improved SERS sensitivity originated from the additional contribution of chemical enhancement, corroborated by the appearance of new Raman bands in the SERS spectrum. For practical applications, SERS based molecule detection requires high sensitivity, specificity, uniformity, and reproducibility of the SERS signal. We demonstrate the simultaneous detection of multiple analytes, with high specificity, from the complex mixture of molecules with different compositions. The fabricated SERS substrates provide excellent signal uniformity and reproducibility with ∼10% relative standard deviation for the multiple substrates. The real-life application of AgSs-based SERS substrates with the spiked apple juice and ITO-coated PET films without pre-processing is also demonstrated.

Ultrasensitive surface‐enhanced Raman spectroscopy detection of explosive molecules with multibranched silver nanostructures

“…The 3D multibranched AgNSts were prepared by the chemical reduction method with the optimum concentrations and the molar ratio of the reagents. [22,23] The welldefined 3D multispiked AgSs were prepared under the optimized reaction parameters AgNO 3 :L-AA (R 1 ) and AgNO 3 :PVP (R 2 ) with values of 0.05 and 2.5, respectively (Figure 1a). The 3D multibranched AgSs with an average size of 2.61 μm exhibit sharp branches with an average arm length of approximately 810 nm and an average tip diameter of 90 nm, as shown in Figure 1c.…”

“…The fabrication of multispiked AgSs was performed with the single‐step reduction of AgNO 3 employing l ‐AA as a reducing agent and PVP as a capping agent. [ 23 ] Under the optimized reaction parameters, 5‐mM AgNO 3 solution was mixed with 10‐mM PVP solution under continuous stirring at room temperature. Then, 500‐mM l ‐AA was dropwise added, and then, the stirring was stopped.…”

“…[ 21,22 ] The single‐step chemical reduction method was employed for the multibranched silver stars (AgSs) fabrication and utilized for the SERS detection of multiple analytes in the individual as well as multiplexed form. [ 23 ]…”

“…[21,22] The single-step chemical reduction method was employed for the multibranched silver stars (AgSs) fabrication and utilized for the SERS detection of multiple analytes in the individual as well as multiplexed form. [23] In this work, the chemically synthesized 3D multibranched AgNSts (silver nanodendrites [AgNDs] and silver stars [AgSs]) are investigated for the ultrasensitive and multiplexed detection of the different analyte molecules; organic dye, pesticide, and explosive molecules by SERS. SERS spectra of individual analytes exhibit the ultralow detectability down to $zeptomolar concentration and high EFs $10 10 with AgND-based substrates.…”

Wafer-scale silver nanodendrites with homogeneous distribution of gold nanoparticles for biomolecules detection

“…The observed significant intensity enhancement is owing to the higher stability (reduced natural oxidation effect) of AgNDs post-deposition of the AuNPs and also the cooperative (synergistic) effect of both AuNDs and AuNPs. The present studies have also been extended toward the detection of trace thiram, which is one of the common pesticides in food safety ( Verma and Soni, 2019 ; Verma and Soni, 2021 ). The determination of substrate quality toward the thiram detection with a range of concentrations (10 μM–10 nM) was considered and the detailed data obtained are shown in Figure 15 A.…”