Optical Properties and Applications of Plasmonic‐Metal Nanoparticles

Abstract

Noble metal nanoparticles due to their unique optical properties arising from their interactions with an incident light have been intensively employed in a broad range of applications. This review comprehensively describes fundamentals behind plasmonics, used to develop applications in the fields of biomedical, energy, and information technologies. Basic concepts (electromagnetic interaction and permittivity of metals) are discussed through Mie theory presented as the main model for interpreting phenomena of optical absorption and scattering. The effects of near‐field enhancement, shape, composition, and surrounding medium of nanoparticles on optical properties are described in detail. The review explores and identifies the potential of plasmonic nanoparticles based on their optical properties (e.g., light absorption, scattering, and field enhancement) for developing different applications (biomedical, energy and information technologies). Due to a significant impact of plasmonic nanoparticles on medicine and healthcare products and technologies, the review initially focuses on biomedical applications extensively benefited from optical features of these nanoparticles. Advantages of the optical properties outstandingly implemented are also briefly discussed in other applications, including energy and information technologies. This review concisely summarizes the explored areas based on plasmonic properties, compares advantages of plasmonic nanoparticles over other types of nanomaterials and highlights challenges.

Photostability of Contrast Agents for Photoacoustics: The Case of Gold Nanorods

“…Conversely, inorganic systems tend to afford more ease of synthesis and manipulation, and to offer higher efficiency of photothermal conversion and higher photo- and chemical stability [ 39 ], i.e., no problems of quenching or premature leakage of dyes in biological fluids. Examples of this kind include ionic compounds like Prussian-blue nanoparticles [ 48 , 49 ], carbon nanotubes [ 50 ] or graphene [ 51 ], and a broad variety of plasmonic particles [ 52 ] that often consist of noble metals like gold. Among the latter class, gold nanorods are one of the most interesting and popular systems [ 4 , 53 ], for the reasons that will be outlined in next paragraph.…”

Plasmonic Nanoparticles as Optical Sensing Probes for the Detection of Alzheimer’s Disease

“…The chemical composition directly affects the interaction of the NPs with the light, so only noble metals such as Au, Ag, Cu, etc. have an LSPR band in the UV ultraviolet (UV)-visible and near-infrared region (NIR) [ 49 ].…”

“…For non-spherical NPs, different plasmon modes are observed, being the anisotropic NPs (e.g., rods, plates, prisms, stars) useful for biomedical applications, due to their LSPR is observed in the NIR where the biological transparency window is located [ 49 , 50 ]. For example, in gold nanorods (AuNRs) two resonance peaks are observed, which correspond to a weak transverse band, located in the visible range and a strong longitudinal resonance, located in the NIR region.…”

“…For example, in gold nanorods (AuNRs) two resonance peaks are observed, which correspond to a weak transverse band, located in the visible range and a strong longitudinal resonance, located in the NIR region. In irregular-shaped NPs as stars, cubes, and others is common to observe broadened plasmon resonance peaks over a wide range of the electromagnetic spectrum due to a more complicated interaction with the light [ 49 , 51 ]. An example of changing the LSPR in UV-vis-NIR spectra by varying the size and shape are shown in Figure 3 A.…”

Spontaneous Radiation Amplification in a Microsphere‐Coupled CsPbBr3 Perovskite Vertical Structure

“…Although plasmonic‐enhanced spontaneous radiation (SR) in metal nanostructures has been employed sophisticatedly, the complicated fabrication process, inherently high energy loss, and Joule‐induced heating are inevitable so far, restricting their applications in devices. [ 27–32 ]…”