Antibacterial Activity and Characteristics of Silver Nanoparticles Biosynthesized From Carduus Crispus

Recently, synthesizing metal nanoparticles using plants has been extensively studied and recognized as a non-toxic and efficient way for biomedical field. The aim of this study is to investigate the role of different parts of Carduus crispus medical plant on synthesizing silver nanoparticles and their characteristics. Our study showed that silver nanoparticles (AgNP) synthesized via whole plant extract exhibited a blue shift in absorption spectra with increased optical density, which correlates to a high yield and smaller size. Also, the results of zeta potential, XRD, PCCS analysis showed the surface charge of -54.29 ±4.96 mV (AgNP-S), -42.64 ±3.762 mV (AgNP-F), -46.02 ±4.17 mV (AgNP-W), the crystallite size of 36 nm (AgNP-S), 13 nm (AgNP-F), 14 nm (AgNP-W) with face-centered cubic structure and average grain size of approximately 100 nm. Another important characteristic, such as elemental composition and constituent capping agent has been determined by EDX and FTIR. The silver nanoparticles were composed of ~80% Ag, ~15% K, and ~7.5% Ca (or ~2.8% P) elements. Moreover, the results of the FTIR measurement suggested that AgNP-F and AgNP-S contained distinct functional groups, on the other hand, AgNP-W contained all of the functional groups present in AgNP-F and AgNP-S. The silver nanoparticles showed antibacterial activity on both gram-negative bacterium Escherichia coli (5.5 ± 0.2 mm to 6.5 ± 0.3 mm) and gram-positive bacterium Micrococcus luteus (7 ± 0.4 mm to 7.7 ± 0.5 mm). Our study is meaningful as a first observation indicating the possibility of using special plant organs to control the characteristics of nanoparticles.