Green Synthesis of Alginate-stabilized Silver Nanoparticles, Its Interaction with Thione Functional Group and Its Antioxidant Scavenging Activity.

Krishnanmurty, Yamunaah (2020) Green Synthesis of Alginate-stabilized Silver Nanoparticles, Its Interaction with Thione Functional Group and Its Antioxidant Scavenging Activity. Final Year Project (Bachelor), Tunku Abdul Rahman University College.

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Abstract

The implementation of the 12 Principles of Green Chemistry in nanoparticles syntheses is a burgeoning research field due to a global movement for sustainable, less hazardous synthesis of chemicals. This thesis entails the successful synthesis and characterization of silver nanoparticles and the evaluation of its anti-oxidative property. Dextrose (a form of glucose) was used to replace a common but harmful reducing agent, namely sodium borohydride. Non-toxic sodium alginate was employed as surfactant instead of the popular hazardous thiol-based surfactants. Additionally, the synthesis was designed to be carried out under ambient conditions, in order to fulfil the Design for Energy Efficiency Principle. The silver nanoparticles synthesized were then studied for its antioxidant scavenging activity because such property may work synergistically with the well-known antibacterial properties of Ag NPs in the future, facilitating the progress of its future commercialization. The synthesized alginate-stabilized silver nanoparticles (Alginate-stabilized Ag NPs) were characterized by UV-Vis absorption spectroscopy, Powder X-ray Diffraction (PXRD), Zeta Potential Analysis, Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDAX). The Alginate-stabilized Ag NPs showed a localized surface Plasmon resonance centered at ~400 nm with the mean zeta potential value of -34.1 mV, higher than the -20mV reported in literature, suggesting an improved colloidal stability. PXRD, SEM and EDAX collectively showed the presence of crystalline Ag NPs (40-70 nm). The Alginate-stabilized AgNPs were further reacted with the thione (C=S) functional group of 4-phenylthiosemicarbazide (PT) with an aim to improve its antioxidant property. The antioxidant scavenging activity was evaluated using the standard 2, 2-diphenyl-1-picrylhydrazyl (DPPH) assay with the order of found as the following: Alginate-stabilized-AgNPs-PT > Alginate-stabilized AgNPs> Vitamin C >PT.