Synthesis of gold nanobipyramids as a sensing material for LSPR sensor.

This study aims to synthesize gold nanobipyramids (GNBPs) and analyze their potential application in LSPR sensor. The synthesis of GNBPs are using two steps seed-mediated growth method, namely seeding and growth process. The GNBPs were characterized using UV-Vis spectroscopy, X-ray diffraction (XRD), and field emission scanning electron microscope (FESEM) to determine their optical, structural, and morphological properties. The UV-Vis absorption spectrum of GNBPs shows that the t-SPR peak appears at the wavelength of 573 nm and the l-SPR peak is located at the wavelength of 755 nm. The results of XRD characterization at a diffraction angle of 30° - 70° showed three diffraction peaks at the diffraction angle of 2θ: 38.06°, 44.36° and 64.44°. The GNBPs have a face-centered cubic (FCC) structure with crystal plane orientation of (111), (200), and (220). From the FESEM image, the percentage surface density of the GNBPs is 78.86% and the average values for length, width, and aspect ratio are 104.85 nm, 43.39 nm, and 2.46, respectively. The GNBPs are used as a sensing material in the LSPR sensor to detect three different types of analytes (DI water, acetone, and chlorpyrifos). Chlorpyrifos is an organophosphate pesticide and toxic to human health. In LSPR sensing response, the spectrum reveals two resonant peaks for each analyte at a different position. The first peak is t-SPR peaks at wavelength positions of 545.95 nm, 546.20 nm, and 546.40 for DI water, acetone, and chlorpyrifos, respectively. Furthermore, as for the l-SPR peaks, the position of each peak is at the wavelengths of 803.40 nm, 803.45 nm, and 803.47 nm. Therefore, the results prove that the implementation of GNBPs as a sensing material has great potential in LSPR sensing applications. [ABSTRACT FROM AUTHOR]