Green Synthesis and Applications of Gold Nanoparticles: From Food Safety to Heavy Metals Detection

Abstract

Nanoscience, an emerging field that bridges science, engineering and technology, has offered solutions to challenges in different sectors including healthcare, food safety, electronics and medicine through the unique properties of nanomaterials. At the heart of these materials, gold nanoparticles have attracted particular attention due to their remarkable optical, electronic and surface properties that make them ideal candidates for different applications. However, traditional synthesis approaches often rely on toxic reagents. This highlights the need for green, safe and sustainable routes. This thesis demonstrates two green approaches for AuNPs synthesis and their applications in sensing. In the first project, curcumin, the main active ingredient in turmeric and a natural polyphenol will act simultaneously as a reducing and capping agent to produce stable AuNPs. These nanoparticles will be employed for the sensing of tert-butylhydroquinone (TBHQ), an antioxidant preservative commonly used in edible oils. Although TBHQ is permitted in limited amounts, its excessive use has been associated with potential health risks, making its monitoring essential. Through fluorescence-based detection, the system offers an efficient, low cost and sustainable method to monitor oil quality. In the second project, ascorbic acid will serve as a green reducing agent while Pluronic, a triblock copolymer, will function as a stabilizer yielding well dispersed AuNPs. The focus will be on the detection of heavy metal ions such as lead using optical techniques like Rayleigh Scattering and absorbance. This approach targets a significant public health concern, as heavy metal contamination in water poses long term risks to the environment and human health. By integrating green synthesis methods with optical detection, this thesis aspires to expand the role of nanotechnology in sustainable development. The focus on food safety assurance and environmental monitoring highlights the potential of AuNPs based sensing systems.