Chlorothalonil-based fungicide has been employed extensively to prevent various
fungal diseases in plants to increase yield of crops. Conversely, over-usage of
chlorothalonil can have adverse effects to human health and environment. An optical
sensor implemented Localized Surface Plasmon Resonance (LSPR) phenomenon
offers direct and simple detection method has been developed for chlorothalonil
detection. In this study, a simple technique of seed-mediated growth method (SMGM)
has been successfully performed to grow gold nanoparticles (GNPs) onto solid
substrates. The process parameters; seeding time, growth time and effect of capping
agent’s molecular weight were investigated to monitor the effect on nanoparticles
formation. It was found that increasing the seeding time affect the surface density of
GNPs. Furthermore, the investigation on growth time shows significant impact to the
shape and size of nanoparticles with 2 hours growth time formed small particles whiles
5 hours and more produces bigger particles. Moreover, in this work, molecular weight
(MW) of polyvinylpyrrolidone (PVP) as shape controlling agent was also investigated
to observe the uniformity of nanoparticles. PVP 55,000 produced more uniform shape
and size of gold nanoparticles compared to PVP 40,000. The prepared sample with 3
hours seeding time, 8 hours growth time and 55k MW of PVP produced highest surface
density of GNPs which is 53.66 ± 1.23 %. This sample was further used as a sensing
material in detection of chlorothalonil. The sensitivity of the sensor system is
determined by measuring the change of peak position and intensity on t-SPR and l�SPR band of GNPs in three mediums; air, deionized water and chlorothalonil solution.
Chlorothalonil with 30 mM concentration (without GNPs) exhibits no significant peak
and thus proven that GNPs is more suitable to be used as sensing material. Besides,
GNPs shows good stability response in 600 seconds with fast response and recovery
time during five cycles change of medium. As a conclusion, the GNPs was
successfully synthesised and used as sensing material for chlorothalonil detection from
1mM to 40 mM
