Investigation of gold nanoparticles for Ganoderma fungi treatment in oil palm trees

Abstract

In recent years, oil palm has been one of the industries that contribute substantially to the gross domestic product of producing countries. As per Plantation Industries and Commodities, palm oil accounted for roughly 66.1% of the total export earnings, reaching RM 44.63 billion in 2022. However, several threats to palm trees, such as Ganoderma basal stem rot disease (BSR), pose risks to our country's gross domestic product. BSR, caused by the fungus Ganoderma boninense, leads to the breakdown and degradation of the lignin trunk of palm trees. Therefore, gold nanoparticles have been fabricated in this project because of their ability to treat fungi. Gold nanoparticles were synthesized in two forms: gold nanorods (GNRs) and gold nanobipyramids (GNBPs) utilizing a wet chemical technique called the Seed-Mediated Growth Method (SMGM). Two plasmon peaks were obtained for synthesized nanoparticles corresponding to transverse surface plasmon resonance (t-SPR) and longitudinal surface plasmon resonance (l-SPR). GNRs have a t-SPR peak at 536 nm and an l-SPR peak at 713 nm, while for GNBPs, a t-SPR peak was obtained at 563 nm and 809 nm for l-SPR peak. For structural properties, the intensity peak at the plane (111) for GNRs and GNBPs occurs at 38.19° and the plane (200) occurs at 44.39°. The surface density of GNRs is 65.26±3.44% and for GNBPs is 69.44±2.94%. For the Ganoderma treatment process, the observation was made for three samples; no control, GNRs and GNBPs. It was found that GNBPs have a high ability to inhibit fungal growth GNRs with no fungal found in their area. In the GNRs area, 20% of fungal growth was found, and there was 60% of fungal growth around no control. In conclusion, GNBPs successfully inhibited fungal growth due to their curvature and sharp edge tips that will interact with microbial cell membranes, resulting in membrane damage and leakage of cellular contents of fungi.