Temperature-dependent green biosynthesis and characterization of silver nanoparticles using balloon flower plants and their antibacterial potential

Abstract

Environmentally benign silver nanoparticles (Ag NPs) were synthesized at different temperatures using leaf extract of Platycodon grandiflorum. The apparent UV–Vis spectrum maxima clearly displayed plasmon resonance bands at 442 and 457 nm for nanoparticles synthesized at 37 °C and 50 °C, respectively. The morphology of Ag NPs were investigated by FESEM, FETEM and AFM analysis and the results showed the formation of uniform spherical nanoparticles with average sizes of 19 and 21 nm for Ag NPs produced at 37 °C and 50 °C, respectively, with slightly larger nanoparticles formed at 50 °C owing to agglomeration. Further characterization by XRD, XPS, and FTIR confirmed their crystal nature, while stability was confirmed by zeta potential analysis. The strong XRD diffraction pattern confirmed the face-central cubic crystalline nature of the nanoparticles. Moreover, XPS revealed Ag 3d doublet (3d5/2 and 3d3/2) with C1s peaks of the catalysts that were turned into CH (283.68) CC, CC (284.16 eV), CO (285.34 eV), and CO (288.55 eV). The O1s spectra were also exhibited with binding energy at 530.94, 531.96 and 532.53 for AgO, CO and CO, respectively, and FTIR confirmed the peaks of plant extract appeared on Ag NPs. Overall, Ag NPs synthesized at 50 °C had good shape and structure with a high stability (−5.23). The nanoparticles also exhibited antibacterial activity against Escherichia coli and Bacillus subtilis. The biosynthesized Ag NPs have the potential for use in various applications, particularly in the field of biomedicine.