Gold Nanoplates for a Localized Surface Plasmon Resonance-Based Boric Acid Sensor

Abstract

Localized surface plasmon resonance (LSPR) properties of metallic nanostructures, such as gold, are very sensitive to the dielectric environment of the material, which can simply be adjusted by changing its shape and size through modification of the synthesizing process. Thus, these unique properties are very promising, particularly for the detection of various types of chemicals, for example boric acid which is a non-permitted preservative employed in food preparations. For the sensing material, gold (Au) nanoplates with a variety of shapes, i.e., triangular, hexagonal, truncated pentagon and flat rod, were prepared using a seed-mediated growth method. The yield of Au nanoplates was estimated to be ca. 63% over all areas of the sensing material. The nanoplates produced two absorption bands, i.e., the transverse surface plasmon resonance (t-SPR) and the longitudinal surface plasmon resonance (l-SPR) at 545 nm and 710 nm, respectively. In the sensing study, these two bands were used to examine the response of gold nanoplates to the presence of boric acid in an aqueous environment. In a typical process, when the sample is immersed into an aqueous solution containing boric acid, these two bands may change their intensity and peak centers as a result of the interaction between the boric acid and the gold nanoplates. The changes in the intensities and peak positions of t-SPR and l-SPR linearly correlated with the change in the boric acid concentration in the solution.

Photoacoustic Imaging: Contrast Agents and Their Biomedical Applications

“…In addition, AuNPs can attain high photothermal conversion effect upon laser illumination and are highly biocompatible, have good chemical inertness, excellent physiochemical properties, and a high extinction coefficient . AuNPs have been synthesized as nanorods, nanoprisms, nanocages, nanospheres, nanostars, nanodisks, bipyramids and rhombic dodecahedra, nanoplates, nanoshells, nanotripods, and nanowreaths …”

Effect of surface modification with various thiol compounds on colloidal stability of gold nanoparticles

“…Colloidal AuNPs show a narrow peak centred at 524 nm that indicates formation of stable AuNPs with diameter of 27.8 nm according to equation (1) : where d (nm) and λ max (nm) are the diameter of nanoparticles and wavelength of absorption peak, respectively. Position and shape of the SPR band depend on the size and form of particles, as well as on the surrounding medium . In the case of AuNPs in aqueous solutions, position at 520–530 nm corresponds to particles of less than 30 nm in diameter.…”

Double-exponential refractive index sensitivity of metal–semiconductor core–shell nanoparticles: the effects of dual-plasmon resonances and red-shift

“…For example, the present LSPR sensors concentrate on detecting the conventional materials whose refractive indices are below 1.6. 28,29 In addition, in most studies, 30,31 the plasmon wavelengths of CSNs have been compared in experiments, but the studies are incomplete due to they didn't pay enough attention to study the reason for plasmon wavelength red-shi of the CSNs in theory.…”