Harnessing barley grains for green synthesis of gold and silver nanoparticles with antibacterial potential.

The continuous evolution and significance of green resources-based nanomaterials have spurred the exploration of sustainable sources for nanoparticle production. Green synthesis routes offer eco-friendly methodologies, ensuring nanoparticle stability and monodispersity, enhancing their efficiency for various applications. Notably, the thick biological corona layer surrounding nanoparticles (NPs) synthesized through green routes contributes to their unique properties. Consequently, there has been a surge in the development of NPs synthesis methods utilizing medicinal plants and diverse agricultural and waste resources. This study highlights the sustainable potential of barley grains for the synthesis of gold nanoparticles (Barley-AuNPs) and silver nanoparticles (Barley-AgNPs) as an environmentally friendly alternative, followed by NPs characterizations and their application against pathogenic bacteria: Escherichia coli UTI 89 and Pseudomonas aeruginosa PAO1. The rapid synthesis of Barley-AuNPs within 20 min and Barley-AgNPs within 30 min at 90 °C underscores the efficiency of barley as a green precursor. Characterization through advanced techniques, including SEM, TEM, EDS, AFM, DLS, FT-IR, MALDI-TOF, and sp-ICPMS, reveals the 20-25 nm size for Barley-AuNPs, while Barley-AgNPs demonstrate 2-10 nm size with spherical monodispersity. A notable contribution lies in the stability of these NPs over extended periods, attributed to a thick biological corona layer. This corona layer, which enhances stability, also influences the antimicrobial activity of Barley-AgNPs, presenting an intriguing trade-off. The antimicrobial investigations highlight the significant potential of Barley-AgNPs, with distinct minimum bactericidal concentrations (MBC) against P. aeruginosa and E. coli at 8 µg/mL. Overall, this research pioneers the use of barley grains for nanoparticle synthesis and unveils these nanoparticles' unique characteristics and potential antibacterial applications, contributing to the evolving landscape of sustainable nanotechnology.