Formation of anisotropic gold nanoparticles on indium tin oxide substrates as a plasmonic sensing material

Abstract

A simple technique of seed-mediated growth has been successfully performed to grow anisotropy gold nanoparticles on solid substrates. The growth of the gold nanoparticles has been carried out in the presence of a binary surfactant mixture of hexadecyltrimethylammonium bromide with two different molecular weights of a capping agent, namely polyvinylpyrrolidone: 40,000 and 55,000. In this study, the effect of process parameters, growth time and molecular weight of capping agent was investigated. The growth time shows a significant impact on the shape and size of nanoparticles. The shorter growth time produced small spherical to square-like shape particles, whereas bigger particles including nanorods, nanosquares and nanotriangles were formed with longer growth time. The shape controlling agent, polyvinylpyrrolidone, was used to synthesis gold nanoparticles. It was found that monodisperse gold nanoparticles with uniform shape and size are hardly obtained when polyvinylpyrrolidone 40,000 was used as capping agent. Polyvinylpyrrolidone 55,000 produced more uniform shape and size of gold nanoparticles. Thus, these process parameters were found affected to the size, shape, surface density and uniformity of gold nanoparticles. This sample was further applied as a sensing material in the detection of toxic fungicide, namely chlorothalonil. The sensitivity of the sensor system was determined by the changes in peak positions and intensities of the transverse and longitudinal surface plasmon resonance peaks on different medium, that is, air, deionized water and chlorothalonil solution. The sensor response of gold nanoparticles thin film in 30 mM chlorothalonil showed two resonance peaks in comparison to the control experiment without gold nanoparticle thin film. The gold nanoparticles thin film sensor was successfully synthesized and potentially useful as a sensing material for fungicide detection.

The role of positively charge poly-L-lysine in the formation of high yield gold nanoplates on the surface for plasmonic sensing application

“…The changes occurred is depending on the refractive index, n. The n for water is 1.333 and 10 mg/L boric acid is 1.3339 with difference is 0.0009. Hence, the wavelength is redshifted when the medium change from DI water to boric acid as well as the intensity increase for higher n. The changes for these sensing responses can be described using Mie theory [27,28,43]. Besides, the PL5-2 with higher density of Au nanoplates has good responses towards different medium as compared to PL5-1.…”

“…Previously, many attempts have been done to produce high yield of nanoplates by investigating the seeding process [ 35 ], growth aging period [ 17 ] and the materials, i.e. surfactants and capping agents used in the synthesis process [ 28 ] and also simplifying the process [ 36 ]. As a result, we found that the implementation of PLL in the synthesizing process successfully promotes high yield of Au nanoplates product especially for hexagon shapes.…”

“…Currently, our group have been working with AuNPs specifically in sensing application [24][25][26][27][28]. The basis of this study started with Au nanosphericals and then further expanded by producing anisotropic nanostructures to enhance and expand the scope of applications.…”

Concave gold nanoparticles on aluminum as surface enhanced Raman spectroscopy substrate for detection of thiram

“…[7][8][9] However, these methods require exhaustive and time-consuming sample preparation and the use of expensive equipment. One of the most promising alternatives is surface enhanced Raman spectroscopy (SERS), 10 because it exhibits rapid response and high sensitivity for the detection of diverse compounds, [11][12][13][14][15] and is an up-and-coming technology that significantly impacts the science and technology of materials, biology, medicine, and environmental monitoring. One of the main challenges for SERS is the design and optimization of suitable substrates that have good features, such as excellent reproducibility, good uniformity, portability, and a high enhancement factor (EF).…”