We report on the synthesis of long silver nanowires using the hydrothermal method, with H2O2 as the reducing agent. Our approach yields nanowires with an average diameter and length of about 100 nm and 160 µm, respectively, reaching the maximum length of 800 µm. Scanning electron microscopy (SEM) measurements revealed the presence of a thick, inhomogeneous poly(vinylpyrrolidone) (PVP) layer covering the nanowires, which with time becomes much more uniform, leading to well-defined extinction peaks in the ultraviolet-visible (UV-Vis) spectra. This change in morphology is evidenced also by the fluorescence enhancement behavior probed using protein complexes. Wide-field and confocal fluorescence microscopy measurements demonstrate strong, 10-fold enhancement of the protein emission intensity, accompanied by a reduction of the fluorescence decay time. In addition, for the aged, one-month-old nanowires, the uniformity of the intensity profile along them was substantially improved as compared with the as-synthesized ones. The results point towards the importance of the morphology of plasmonically active silver nanowires when considering their application in enhancing optical properties or achieving energy propagation over submillimeter distances.
We observe correlation between the length of surface plasmon polariton propagation in silver nanowires and the enhancement of fluorescence intensity due to coupling with localized plasmon resonances. The results of excitation wavelength-dependent fluorescence imaging of CdTe QDs uniformly deposited over silver nanowires indicate the strongest enhancement of fluorescence intensity for wavelengths close to the maximum of localized plasmon resonance, with modest reduction of this effect when the excitation shifts toward longer wavelengths. In contrast, when one of the ends of a silver nanowire is excited with a focused laser, we find a reverse relation for surface plasmon polariton propagation. In fact, the energy propagates most efficiently for the longest excitation wavelength of 635 nm. This inverse correlation points toward an apparent trade-off between electric field confinement and plasmon propagation distance in silver nanowires, introducing thus a limit for efficient remote fluorescence detection when fluorescence enhancement is also desired.
Silver nanowires with varying diameters and submillimeter lengths were obtained by changing a reducing agent used during hydrothermal synthesis. The control over the nanowire diameter turns out to play a critical role in determining their plasmonic properties, including fluorescence enhancement and surface plasmon polariton propagation. Advanced fluorescence imaging of hybrid nanostructures assembled of silver nanowires and photoactive proteins indicates longer propagation lengths for nanowires featuring larger diameters. At the same time, with increasing diameter of the nanowires, we measure a substantial reduction of fluorescence enhancement. The results point at possible ways to control the influence of plasmon excitations in silver nanowires by tuning their morphology.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.