Biosynthesis of Silver and Gold Nanoparticles Using Aqueous Extract of <i>Codonopsis pilosula</i> Roots for Antibacterial and Catalytic Applications
Van‐Dat Doan, Bao-An Huynh, Thanh–Danh Nguyen, Xuan-Thang Cao, Van Cuong Nguyen, Thi Lan-Huong Nguyen, Hoài Thương Nguyễn, Van Thuan Le
Abstract
In this study, biogenic silver nanoparticles (AgNPs) and gold nanoparticles (AuNPs) were synthesized by a green approach using an aqueous extract from Codonopsis pilosula (CP) roots as a reducing and stabilizing agent. The formation of CP-AgNPs and CP-AuNPs was confirmed and optimized by UV-Vis spectroscopy. The CP-AgNPs and CP-AuNPs obtained under optimum conditions of metal ion concentration, reaction temperature, and reaction time were characterized by high-resolution transition electron microscopy (HR-TEM), selected area electron diffraction (SAED) analysis, field-emission scan electron microscopy (FE-SEM), powder X-ray diffraction (XRD) analysis, Fourier transform infrared (FTIR) spectroscopy, dispersive X-ray spectroscopy (EDX), and dynamic light scattering (DLS) method. It has been found that the biosynthesized CP-AgNPs and CP-AuNPs were formed in spherical shape with an average size of <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M1"><mml:mn>10</mml:mn><mml:mo>±</mml:mo><mml:mn>2.5</mml:mn><mml:mtext> </mml:mtext><mml:mtext>nm</mml:mtext></mml:math> and <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="M2"><mml:mn>20</mml:mn><mml:mo>±</mml:mo><mml:mn>3.2</mml:mn><mml:mtext> </mml:mtext><mml:mtext>nm</mml:mtext></mml:math>, respectively. The biosynthesized metallic nanoparticles exhibited selective bacterial activity against three bacterial strains including two Gram-positive bacteria of Bacillus subtilis and Staphylococcus aureus and one Gram-negative bacteria of Escherichia coli . Meanwhile, there was no antibacterial activity detected toward Gram-negative Salmonella enteritidis. CP-AgNPs and CP-AuNPs also manifested an excellent catalytic performance in the reduction of 1,4-dinitrobenzene, 2-nitrophenol, 3-nitrophenol, and 4-nitrophenol.