Green synthesis of metallic nanoparticles (Ag, Au and Cu) obtained from the residues (peel/pulp) of guarana (Paullinia cupana) and determination of their antibacterial activity

Author(s)

Gustavo Henrique Barroso da Silva

• Document type: Master's Dissertation
• Press: Lorena.
• Institution: Universidade de São Paulo (USP). Escola de Engenharia de Lorena (EEL/ASDI)
• Defense date: 2024-11-21

Examining board members

Fabio Rodolfo Miguel Batista; Julian Martínez

• Advisor: Fabio Rodolfo Miguel Batista

Abstract

This work aimed to develop a green route to produce metallic nanoparticles (NPs) (Ag, Au and Cu) using an extract obtained from residues (peel/pulp) of guarana, in addition to investigating the antimicrobial activity of these extracts and the NPs produced. Renewable solvents (water and ethanol) were used to produce extracts from dry and wet biomass. Silver nitrate, tetrachloroauric acid and copper sulfate were used as precursors of the metals. The extracts were characterized by the Folin-Ciocalteau technique and gas chromatography coupled with mass spectrometry. The NPs were characterized by Ultraviolet and Visible Light Absorption Spectroscopy (UV-vis), X-ray Diffraction (XRD), Fourier Transform Infrared Spectroscopy (FTIR), Transmission Electron Microscopy (TEM) and Dynamic Light Scattering (DSL). The aqueous extract presented a more adequate content of total phenolic compounds and was chosen for the synthesis of NPs. As ideal conditions, an extract:precursor volumetric ratio of 1:10 for AgNPs and 1:5 for AuNPs, an extract concentration of 25 mg.mL-1 for both NPs, a precursor concentration of 1.10-2 molL-1 for AgNPs and 1.10-3 molL-1 for AuNPs, a reaction temperature of 40 °C for AgNPs and 60 °C for AuNPs, and a synthesis time of 6 h for AgNPs and 2 h for AuNPs were the best reaction conditions. AgNPs presented a spherical shape while AuNPs had a hexagonal predominance. For both NPs, the size distribution range was between 11 and 44 nm, with a high aggregation. The oxidized extract showed greater antimicrobial activity than the NPs themselves. Therefore, the proposed method proved to be a viable alternative to traditional methods of obtaining metallic NPs, enabling the use of a waste with no economic value to obtain products with higher added value. (AU)

• FAPESP's process: 22/04066-5 - GREEN SYNTHESIS OF METALLIC NANOPARTICLES (Ag, Au and Cu) AND DETERMINATION OF THE THERAPEUTIC ACTIVITY OF EXTRACTS OBTAINED FROM GUARANA (Paullinia cupana) RESIDUES (BARK/PULP)
• Grantee: Gustavo Henrique Barroso da Silva
• Support Opportunities: Scholarships in Brazil - Master