Abstract
Noble metal, especially gold (Au) and silver (Ag) nanoparticles exhibit unique and tunable optical properties on account of their surface plasmon resonance (SPR). In this paper, we mainly discussed the theory background of the enhanced optical properties of noble metal nanoparticles. Mie theory, transfer matrix method, discrete dipole approximation (DDA) method, and finite-difference time domain (FDTD) method applied brute-force computational methods for different nanoparticles optical properties. Some important nanostructure fabrication technologies such as nanosphere lithography (NSL) and focused ion beam (FIB) are also introduced in this paper. Moreover, these fabricated nanostructures are used in the plasmonic sensing fields. The binding signal between the antibody and antigen, amyloid-derived diffusible ligands (ADDLs)-potential Alzheimer's disease (AD) biomarkers, and staphylococcal enterotixn B (SEB) in nano-Moore per liter (nM) concentration level are detected by our designed nanobiosensor. They have many potential applications in the biosensor, environment protection, food security, and medicine safety for health, and so forth, fields.
Highlights
The intense scattering and absorption of light from noble metal nanoparticles is the source of the beautiful colors in stained glass windows and has attracted the interest of scientists for generations
Scientists have learned that the characteristic hues of these noble metal nanoparticle suspensions arise from their strong interaction with light, the advent of the field of nanoparticle optics has allowed for a deeper understanding of the relationship among material properties, local dielectric environments, and the observed color of a metal suspension
localized surface plasmon resonance (LSPR) excitation results in wavelength selective absorption with extremely large molar extinction coefficients ∼3 × 1011 M−1 cm−1 [6], resonant Rayleigh scattering [7, 8] with an efficiency equivalent to that of 106 fluorophors [9, 10], and the enhanced local electromagnetic fields near the surface of the nanoparticle which are responsible for the intense signals observed in all surface-enhanced spectroscopies [11]
Summary
The intense scattering and absorption of light from noble metal nanoparticles is the source of the beautiful colors in stained glass windows and has attracted the interest of scientists for generations. Journal of Nanomaterials different nanoparticle-based sensing mechanisms that enable the transduction of macromolecular or chemical binding events into optical signals based on changes in the LSPR extinction or scattering intensity, shifts in LSPR λmax, or both These mechanisms are (1) resonant Rayleigh scattering from nanoparticle labels in a manner analogous to fluorescent dye labels [12]; (2) nanoparticle aggregation [13]; (3) charge-transfer interactions at nanoparticle surfaces [14, 15]; and (4) local refractive index changes [16]. Golden metal nanoparticles with different materials, sizes, periods, and refractive index of the medium around the nanoparticles can scatter the light of different wavelengths according to their characteristic SPR [19] The target molecules such as proteins or virus can bind to the surface of the metal after chemical prefunction of the nanoparticles [20]. Examples of detecting various types of biomolecules based on refractive-index plasmonic sensing principle will be presented
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