Green synthesis and characterization of silver nanoparticles using banana peel extract and their antimicrobial activity against representative microorganisms

The present study reports an eco-friendly, cost efficient, rapid and easy method for synthesis of silver nanoparticles using banana peel extract (BPE) as a reducing and capping agent. The different factor affecting silver reduction was investigated. The optimum conditions were silver nitrate (1.75 mM), BPE (20.4 mg dry weight), pH (4.5) and incubation time (72 h). BPE can reduces silver ions into silver nanoparticles within 5 min after heating the reaction mixture (40–100 °C) as indicated by the developed reddish brown color. The UV–Vis spectrum of silver nanoparticles revealed a characteristic surface plasmon resonance (SPR) peak at 433 nm. Silver nanoparticles were characterized. X ray diffraction revealed their crystalline nature. Scanning electron microscope and field emission scanning electron microscope showed spherical shaped and monodispersed nanoparticles. Transmission electron microscope confirmed the spherical nature and the crystallinity of nanoparticles. The average size of nanoparticles was 23.7 nm as determined by dynamic light scattering. Energy dispersive X-ray spectroscopy analysis showed the peak in silver region confirming presence of elemental silver. Fourier transform infrared spectroscopy affirmed the role of BPE as a reducing and capping agent of silver ions. Silver nanoparticles showed effective antibacterial activity against representative pathogens of bacteria and yeast. The minimum inhibitory concentration and minimum bactericidal concentration were determined. The synthesized nanoparticles showed synergistic effect with levofloxacin antibiotic, the antimicrobial activity increased by 1.16–1.32 fold.