Gold nanorods (Au NRs) are elongated nanoparticles with unique optical properties which depend on their shape anisometry. The Au NR-based longitudinal localized surface plasmon resonance (longitudinal LSPR) band is very sensitive to the surrounding local environment and upon the addition of target analytes, the interaction between the analytes and the surface of the Au NRs leads to a change in the longitudinal LSPR band. This makes it possible to devise Au NR probes with application potential to the detection of toxic metal ions with an improved limit of detection, response time, and selectivity for the fabrication of sensing devices. The effective surface modification of Au NRs helps in improving their selectivity and sensitivity toward the detection of toxic metal ions. In this review, we discuss different methods for the preparation of surface modified Au NRs for the detection of toxic metal ions based on the LSPR band of the Au NRs and the types of interactions between the surface of Au NRs and metal ions. We summarize the work that has been done on Au NR-based longitudinal LSPR detection of environmentally toxic metal ions, sensing mechanisms, and the current progress in various modified Au NR-based longitudinal LSPR sensors for toxic metal ions. Finally, we discuss the applications of Au NR-based longitudinal LSPR sensors to real sample analysis and some of the future challenges facing longitudinal LSPR-based sensors for the detection of toxic metal ions toward commercial devices.
Enhanced red and orange fluorescence emissions of Sm3+ Rare earth (RE) ions were observed in sodium‑zinc tellurite glasses embedded with silver and gold nanoparticles (NPs). The fine distribution of NPs in the glass matrix with an average diameter ~ 11.09 nm and ~3.86 nm for Ag and Au NPs respectively were confirmed by using transmission electron microscope (TEM). The embedding of Ag and Au NPs into the glass structure caused an increasing in the transition emission intensity of Sm3+ ions, which is ascribed to the progress of the presence of the localized surface Plasmon resonance (LSPR) indicating from the characteristic absorption peaks. The luminescence and absorption spectra have been discussed using a standard hypothesis Judd-Ofelt theory for a certain absorption transitions 6P3/2, 4I11/2, 6F11/2, 6F9/2, 6F7/2, 6F5/2, 6F3/2, 6H15/2, 6F1/2 and emission transitions 6H5/2, H7/2, 6H9/2 and H11/2 under 409 nm excitation of the Sm3+ ions. The decay life time curve exhibited a non-exponential behavior of the studied glass samples and the results were compared with the similar reported glasses. An efficient red and orange fluorescence emission illustrate that the Sm3+-doped sodium‑zinc tellurite embedded with Ag and Au NPs are potential materials for the laser illumination.
In recent years, the field of nanophotonics has progressively developed. However, constant demand for the development of new light source still exists at the nanometric scale. Light emissions from graphene-based active materials can provide a leading platform for the development of two dimensional (2-D), flexible, thin, and robust light-emitting sources. The exceptional structure of Dirac's electrons in graphene, massless fermions, and the linear dispersion relationship with ultra-wideband plasmon and tunable surface polarities allows numerous applications in optoelectronics and plasmonics. In this article, we present a comprehensive review of recent developments in graphene-based light-emitting devices. Light emissions from graphene-based devices have been evaluated with different aspects, such as thermal emission, electroluminescence, and plasmons assisted emission. Theoretical investigations, along with experimental demonstration in the development of graphene-based light-emitting devices, have also been reviewed and discussed. Moreover, the graphene-based light-emitting devices are also addressed from the perspective of future applications, such as optical modulators, optical interconnects, and optical sensing. Finally, this review provides a comprehensive discussion on current technological issues and challenges related to the potential applications of emerging graphene-based light-emitting devices.