Ag Nanostructures with Spikes on Adhesive Tape as a Flexible Sers-Active Substrate for In Situ Trace Detection of Pesticides on Fruit Skin

Abstract

Nanostructures with spikes (NSPs) have been a subject of several surface-enhanced Raman scattering (SERS) applications owing to their significant Raman signal enhancement brought about by the combined effects of interspike coupling and the accumulated induction on the tips of spikes. Thus, NSPs offer great potential as a SERS-active substrate for relevant applications that require a high density of enhanced “hot spots”. In this study, Ag NSPs were synthesized in varying degrees of agglomeration and were thereafter deposited onto a transparent adhesive tape as a flexible substrate for SERS applications, specifically, in the detection of trace amounts of pesticides. These flexible substrates were referred to as Ag NSPs/tape and optimized with an enhancement factor (EF) of ca. 1.7 × 107. A strong resulting signal enhancement could be attributed to an optimal degree of agglomeration and, consequently, the distances among/between spikes. Long spikes on the synthesized core of Ag NSPs tend to be loosely spaced, which are suitable in detecting relatively large molecules that could access the spaces among the spikes where “hot spots” are generally formed. Since one side of the transparent tape is adhesive, the paste-and-peel off method was successful in obtaining phosmet and carbaryl residues from apple peels as reflected in the acquired SERS spectra. In situ trace detection of the pesticides at low concentrations down to 10−7 M could be demonstrated. In situ trace detection of mixed pesticides was possible as the characteristic peaks of both pesticides were observed in equimolar mixtures of the analytes at 10−2 to 10−4 M. This study is, thus, premised upon applying for in situ trace detection on e.g., fruit skin.

LSPR immuno-sensing based on iso-Y nanopillars for highly sensitive and specific imidacloprid detection

“…As known from the literature, the formation of hot spots is favored in proximity of tips and the Y shape taken into account shows a number of tips which is double those shown in the more conventional triangular shape. [36][37][38] As expected, depending on the polarization used for the FEM analysis, the iso-Y NP shows six hot spots corresponding to the vertices of the different branches that can be associated with the LSPR effects. For both polarizations, the maximum size and intensity of the hot spots are achieved for wavelengths of around 850 nm.…”

Silver Nanoparticles as Colorimetric Sensors for Water Pollutants

“…On the other hand, the void area has been used to tune the refractive index, increase the active region for catalysis, and advance the ability to tolerate cyclic volume modifications. The morphology plays a key role, especially for the possibility of having materials with different symmetries (spheres, AgNPs, cubes AgNCs) [79][80][81][82][83][84][85][86][87] or without defined and reproducible symmetry (stars, AgNSs, flower, AgNFs, wires, AgNWs) [69,[88][89][90][91][92][93][94]. TEM images of silver nanoparticles of different geometries and shape are presented in Figure 4.…”

Flexible Surface‐Enhanced Raman Scattering Substrates: A Review on Constructions, Applications, and Challenges

“…Generally, the SERS tape was demonstrated by dropping plasmonic nanostructures onto the tapes, and analytes can be easily detected by the “paste and peel off” method. [ 117,118,129 ] To solve the nonuniformity of plasmonic nanostructures on the tape, Jiang et al. [ 25 ] fabricated a tape‐wrapped SERS substrate by combining the adhesive tape and Al 2 O 3 ‐coated AgNRs.…”