This work aims to fabricate two types of plasmonic nanostructures by electrical exploding wire (EEW) technique and study the effects of the different morphologies of these nanostructures on the absorption spectra and Surface-Enhanced Raman Scattering (SERS) activities, using Rhodamine 6G as a probe molecule. The structural properties of these nanostructures were examined using X-Ray diffraction (XRD). The morphological properties were examined using field emission scanning electron microscopy (FESEM) and scanning transmission electron microscopy (STEM). The absorption spectra of the mixed R6G laser dye (concentration 1×10-6 M) with prepared nanostructures were examined by double beam UV-Vis Spectrophotometer. The Raman spectra of the R6G mixed with the prepared nanostructures were examined using a Horiba HR Evolution 800 Raman microscope system with an objective lens (50 ×). The FESEM and STEM images indicated that the Ag nanoparticles (AgNPs) with 35 nm average particle sizes were decorated on the surface of the AgNWs and the PDA layer by EEW technique, forming AgNW@AgNPs and AgNW@PDA@AgNPs nanostructures. The results indicated that the increased intensities of the absorption spectra peaks and the SERS arise from the hot spots and the roughness of the surface of nanostructures. The SERS enhancement factor of R6G (1×10-6 M) was reached at 2.3×107 and 2.5×107, at the wave number of 1650 cm-1, for the AgNW@AgNPs and AgNW@PDA@AgNPs nanostructures, respectively, after being excited by (λexc. = 532 nm) laser source. It can be concluded that the AgNW@AgNPs and AgNW@PDA@AgNPs nanostructures were fabricated with an easy and simple way without the need for additional chemical compounds. These nanostructures attained a reliable and sensitive detection and can be utilized in a variety of SERS applications, such as chemical and biological sensors.
One of the rapidly growing fields of nanotechnology is its manipulation of laser dyes' properties using nanoparticles and nanostructures due to its various applications, ranging from biomedical imaging to green energy. Silver nanoparticles (Ag NPs) of various concentrations and nanostructures with silver nanowire (Ag NW) were prepared using an electrical exploding wire technique (EEW) and was mixed with a fixed concentration of R6G dye. The behavior of energy transfer from the dye molecules (R6G) to nanomaterials (Ag NPs or plasmonic nanostructures) was examined using fluorescence spectra. The experimental results showed that the fluorescence intensity quenched with increasing concentration and density number of Ag NPs. The distance between the dye molecules and the nanostructures was studied, which was found to decrease as the concentration and density number of Ag NPs increased in the mixture. The energy transfer efficiency of nanostructures was compared. It was obtained that nanostructure (Ag NW@PDA@Ag NPs) achieved the best energy transfer efficiency of 85%. Our results indicated that this nanostructure could sense a distance around the metal nanoparticles (≈ 27.2 nm); thus the nanoparticle-based surface energy transfer (NSET) mechanism is dominated rather than Förster resonance energy transfer (FRET) mechanism. This process is affected by concentration increasing of Ag NPs and coated morphology of Ag NWs by polydopamine (PDA) layer decorated by Ag NPs. The findings can be utilized in the large field of bio diagnostics and biochemistry. Regardless of bio-applications, the quenching mechanisms and rates are also of interest for SERS, (dye-sensitized) solar cells or nanooptics. However, we see the best potential in bio-sensing by managing the quenching rate by adjusting the shape or the concentration of nanostructures.
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