Microwave-Assisted Biosynthesis of Quercetin-Stabilized Gold Nanoparticles with Enhanced Antibacterial and Catalytic Properties

In the past few years, substantial progress has been made in the field of microwave-assisted biosynthesis of gold nanoparticles (AuNPs) using quercetin (QT) as a natural reducing and stabilizing agent. This study explores the rapid and eco-friendly synthesis of AuNPs facilitated by microwave irradiation, offering a time-efficient alternative to conventional methods. The AuNPs were thoroughly characterized to confirm their morphology, size, crystalline structure, and surface plasmon resonance (SPR). The synthesized AuNPs were confirmed by visual color change from yellow to violet and characteristic SPR peak at 519 nm. Furthermore, XRD studies clearly confirmed the crystalline nature of the face-centered cubic structure of AuNPs. Moreover, TEM images reveal that the AuNPs were found to be more or less spherical and have a slightly variable morphology with an average diameter of 14 nm. The antibacterial properties of QT and AuNPs were evaluated against two different bacterial strains via <i>Staphylococcus aureus</i> and <i>Escherichia coli</i>, demonstrating significant activity, particularly due to the stabilizing effect of QT. Additionally, the catalytic efficiency of the AuNPs was evaluated by their ability to reduce 4-nitrophenol to 4-aminophenol, a model reaction for the catalytic activity. The results were promising, with the rate constant of QT-AuNPs determined to be 0.1016 s^-1. This work highlights the dual functionality of QT-mediated AuNPs in enhancing both antimicrobial and catalytic properties, contributing to their potential applications in the biomedical and environmental fields. This study highlights the dual role of QT-mediated AuNPs in enhancing antimicrobial and catalytic properties, paving the way for innovative applications in both the biomedical and environmental fields. The uniqueness lies in leveraging the natural properties of QT to simultaneously improve biological activity and catalytic efficiency, offering a sustainable and multifunctional QT-AuNP solution.