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.
Seed-mediated growth method (SMGM) in preparation of gold nanoparticles becomes one of the most popular methods due to the simplicity of the experimental procedures and flexibility in structural modifications. In this paper, we report a new method for synthesizing gold nanoparticles using silver seeds. The effect of seed concentration and growth time are investigated in this work. By increasing the silver seed concentration, it is found that the color of the colloidal gold nanorods obtained are changed from light pink to reddish purple, the surface plasmon resonance band is shifted to the blue region whereas absorption spectra becomes narrower. The additional peak is also spotted when increasing silver seed concentration to 5 µl. Meanwhile, increasing the growth time from 5 to 240 minutes tends to increase the color concentration of the solution. Besides that, the absorbance of colloidal gold nanorods is also increased with an increase in the growth time whereas optimum growth time is found to be 45 minutes. FESEM characterization shows that gold nanoparticles shapes are dominated by nanorods with average length, width, and aspect ratio are 129.8 nm, 42.9 nm, and 3.4, respectively. The energy-dispersive x-ray spectroscopy (EDX) shows the chemical composition of the synthesized sample is Gold (Au) with weight % and atomic % are 32.23 and 5.98, respectively. Besides that, signals from Carbon (C), Oxygen (O), and Indium (In) atoms were also recorded from EDS spectra. The present approach thus provides new method for synthesis gold nanoparticles with additional plasmon resonance peak thus it has very potential for application in plasmonic sensing.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.