3D ZnO/Ag Surface-Enhanced Raman Scattering on Disposable and Flexible Cardboard Platforms

Abstract

In the present study, zinc oxide (ZnO) nanorods (NRs) with a hexagonal structure have been synthesized via a hydrothermal method assisted by microwave radiation, using specialized cardboard materials as substrates. Cardboard-type substrates are cost-efficient and robust paper-based platforms that can be integrated into several opto-electronic applications for medical diagnostics, analysis and/or quality control devices. This class of substrates also enables highly-sensitive Raman molecular detection, amiable to several different operational environments and target surfaces. The structural characterization of the ZnO NR arrays has been carried out by X-ray diffraction (XRD), scanning electron microscopy (SEM) and optical measurements. The effects of the synthesis time (5–30 min) and temperature (70–130 °C) of the ZnO NR arrays decorated with silver nanoparticles (AgNPs) have been investigated in view of their application for surface-enhanced Raman scattering (SERS) molecular detection. The size and density of the ZnO NRs, as well as those of the AgNPs, are shown to play a central role in the final SERS response. A Raman enhancement factor of 7 × 105 was obtained using rhodamine 6 G (R6G) as the test analyte; a ZnO NR array was produced for only 5 min at 70 °C. This condition presents higher ZnO NR and AgNP densities, thereby increasing the total number of plasmonic “hot-spots”, their volume coverage and the number of analyte molecules that are subject to enhanced sensing.

Fabrication of Interconnected Plasmonic Spherical Silver Nanoparticles with Enhanced Localized Surface Plasmon Resonance (LSPR) Peaks Using Quince Leaf Extract Solution

“…Pimentel et al [21] synthesized zinc oxide nanorods (ZnO NRs) arrays through a hydrothermal technique supported by radiation of microwave on cardboard materials substrates coated with a ZnO seed thin film. The ZnO NRs were decorated with Ag NPs.…”

Enhanced UV Flexible Photodetectors and Photocatalysts Based on TiO2 Nanoplatforms

“…The TiO 2 growth on cellulose-based substrates without any seed layer or chemical treatment for adhesion are expected to be due to substrate roughness facilitating nucleation and fixation of the TiO 2 structures. Other metal-oxide based materials have been shown to grow on cellulose-based substrates, however, a seed layer was required for this process to occur [46][47][48]. The thickness of the films grown on BNC and tracing paper could not be inferred precisely due to heterogeneities of the structures formed, while the TiO 2 nanorod film grown on the polyester substrate revealed a thickness average of 167 ± 9 nm (see Fig.…”

Bottom-up microwave-assisted seed-mediated synthesis of gold nanoparticles onto nanocellulose to boost stability and high performance for SERS applications

“…[2,[7][8][9] Various SERS platforms have been reported using microwave-assisted synthesis to produce enhancement nanostructures and are mostly based on Ag nanostructures. [1,2,6,7,[10][11][12][13] Although AgNPs are able to provide the highest Raman enhancements, due to their strong plasmon resonance effect, they are chemically unstable and prone to early oxidation, which can compromise the shelf life of SERS platforms. [14] On the contrary, AuNPs have high chemical stability, are biocompatible and offer easy functionalization with biomarkers.…”

“…[8,13,24,[26][27][28][29][30] Since the first reports on cellulose as SERS platform in 1984, [31,32] several cellulose-based SERS substrates have been proposed in the literature, with different cellulose formats, nanostructures fabrication strategies and deposition methods. [11,13,14,[33][34][35] Among the deposition methods, in situ synthesis methods [36][37][38][39][40] show benefits since the nanostructures' production and their deposition on the substrate can be done in a single step. This generally leads to simple and fast SERS platform's fabrication, avoiding, for instance, long immersion times of the substrate onto plasmonic nanoparticles colloidal solutions.…”