Biogenic Silver Nanoparticles by Cacumen Platycladi Extract: Synthesis, Formation Mechanism, and Antibacterial Activity

Abstract

Biosynthesis of Ag nanoparticles (AgNPs) by Cacumen Platycladi extract was investigated. The AgNPs were characterized by ultravioletÀvisible absorption spectroscopy (UVÀvis), transmission electron microscopy (TEM), selected-area electron diffraction (SAED), and X-ray diffraction (XRD). The results showed that increasing the initial AgNO 3 concentration at 30 or 60 °C increased the mean size and widened the size distribution of the AgNPs leading to red shift and broadening of the Surface Plasmon Resonance absorption. The conversion of silver ions was determined by atomic absorption spectroscopy (AAS) and to discuss the bioreductive mechanism, the reducing sugar, flavonoid, saccharide, protein contents in the extract, and the antioxidant activity were measured using 3,5-dinitrosalicylic acid colorimetric; Coomassie brilliant blue; phenol-sulfuric acid; rutin-based spectrophotometry method; and 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical-scavenging assay methods. The results showed that the reducing sugars and flavonoids were mainly responsible for the bioreduction of the silver ions and their reductive capability promoted at 90 °C, leading to the formation of AgNPs (18.4 ( 4.6 nm) with narrow size distribution. Finally, the antibacterial activity of the AgNPs against E. coli and S. aureus was assessed to determine their potential applications in silver-loaded antibacterial materials. This work provides useful technical parameters for industrialization of the biosynthetic technique and further antibacterial application of the AgNPs. Furthermore, the elucidation of bioreductive mechanism of silver ions by measuring the change of the biomolecular concentrations in plant extract exemplifies understanding the formation mechanism of such biogenic AgNPs.

Phytosynthesis of eco-friendly silver nanoparticles and biological applications A novel concept in nanobiotechnology

“…Christensen et al (2011) studied the biological synthesis of AgNPs using Murraya koenigii leaf extract and the effect of broth concentration on reduction mechanism and particle size. Huang et al (2011) reported that increasing the AgNO 3 concentration at 30 or 65°C increased the mean size and the size distribution of the AgNPs. Singhal et al (2011) reported that Ocimum sanctum leaf extract can reduce AgNO 3 into AgNPs within 8 min of reaction time.…”

Biosynthesis of silver nanocomposite with Tarragon leaf extract and assessment of antibacterial activity

“…Briefly, AgNPs at 5, 0.5, and 0.05 μg/mL were used to prevent E. coli (ATCC 25922) and S. aureus (ATCC 25923) growth. Bacterial cultures at a concentration of 1.5 × 10 8 CFU/mL were inoculated with different concentrations of AgNPs [31]. After incubating the culture plates at 37 °C for 24 h, the bacterial growth inhibition zone was measured in millimeters [32].…”

Silver Nanoparticles

“…Reducing sugars and flavonoids in the extract seemed to be mainly responsible for reduction of silver ions, and their reductive capability promoted at 90 °C, leading to formation of silver nanoparticles (18.4 ± 4.6 nm) with narrow size distribution. The produced nanoparticles had significant antibacterial activity against both gram negative and gram positive bacteria (E. coli and S. aureus) (Huang et al 2011). In case of Cinnamon zeylanicum, the bark extract could be used in biosynthesis of cubic and hexagonal silver nanocrystals (31-40 nm) (Sathishkumar et al 2009).…”