Extracellular directed ag NPs formation and investigation of their antimicrobial and cytotoxic properties.

The use of microbial cell culture a valuable tool for the biosynthesis of nanoparticles is considered a green technology as it is eco-friendly, inexpensive and simple. Here, the synthesis of nanosilver particle (AgNP) from the yeast, Saccharomyces cerevisiae, gram (+), Bacillus subtilis and gram (-), Escherichia coli was shown. In this field we are the first to study their the antimicrobial effects of the microorganisms mentioned above against pathogens and anticancer activity on MCF-7 cell line. Silver nanoparticles in the size range of 126-323 nm were synthesized extracellularly by the microorganisms, which have different cell structures. Optical absorption, scanning electron microscopy, and zetasizer analysis confirmed the silver nanoparticles formation. Antimicrobial activity of AgNPs was evaluated the minimum inhibition concentration and disc diffusion methods. AgNPs inhibited nearly 90% the growth of Gram-positive Listeria monocytogenes, Streptococcus pneumoniae and Gram-negative Haemophilus influenzae, Klebsiella pneumoniae, Neisseria meningitidis bacterial pathogens. Anticancer potentials of AgNPs were investigated by MTT method. The synthesized AgNPs exhibited excellent high toxicity on MCF-7 cells and had a dose-dependent effect on cell viability. Especially AgNP 2 eliminated 67% of the MCF-7 cells at the concentration of 3.125 µg/mL. We found that extracellular synthesis of nanoparticles from microbial culture may be 'green' alternative to physical and chemical methods from the point of view of synthesis in large amounts and easy process.

Formation of Matricaria chamomilla extract-incorporated Ag nanoparticles and size-dependent enhanced antimicrobial property.

Various concentrations of Matricaria chamomilla (M. chamomilla) flower extract was used for biosynthesis of Ag NPs with different sizes, 70±5 (Ag NP-1), 52±5 (Ag NP-1) and 37±4nm (Ag NP-3), and size-specific antimicrobial activity of them was evaluated towards Gram+ Staphylococcus aureus (S. aureus), Gram- Escherichia coli (E. coli) bacteria and Candida fungus albicans (C. albicans). We also examine the formation of Ag NPs as a function of the plant extract volume, Ag ion concentration (Ag+) and reaction time. M. chamomilla flower extract at 100ppm shows mild inhibitory effect by inhibiting growth of all target pathogens. The extract mediated Ag NPs even at low concentration (6.25ppm) caused reductions in cell densities of the pathogens. The potential reasons for the highly effective inhibitory activity of the extract mediated Ag NPs are: (1) synergistic effects due to combination of M. chamomile extract and Ag NP because Ag NP is an effective germicidal and M. chamomile plant itself shows mild inhibitory property, (2) high localized concentration of M. chamomile extract due to nano scale entrapment of it on surface of Ag NP and (3) size-specific antibacterial efficacy of Ag NP because small size increases the active surface area of Ag NP, which reacting bacterial cells and increases number of extract molecules anchored on the surface of Ag NP.

The Effect of Pelargonium endlicherianum Fenzl. root extracts on formation of nanoparticles and their antimicrobial activities.

Herein, we report the biosynthesis of Ag NPs, for the first time, using identified antimicrobial molecules (gallic acid+apocynin) and (gallic acid+apocynin+quercetin) from the medicinal plant Pelargonium endlicherianum Fenzl. and dramatically enhanced antimicrobial activity. We also investigate the role of each molecule on formation Ag NPs and explain the increase in the antimicrobial activity of identified molecules mediated Ag NPs. The extraction protocols, 11% ethanol and 70% methanol, resulted in identification of different constituents of gallic acid+apocynin (M1) and gallic acid+apocynin+quercetin (M2) with respective concentrations. The M1-Ag and M2-Ag NPs exhibit excellent inhibitory activities towards Gram negative bacteria; Escherichia coli ATCC 25922, Pseudomonas aeruginosa ATCC 27853 and Gram positive bacteria; Staphylococcus epidermidis ATCC 3699 bacterial using in vitro microdilution method. The minimum inhibitory concentration (MIC) values of M1-Ag and M2-Ag NPs were determined to be 7.81 and 6.25ppm for S. epidermidis, respectively. Surprisingly, MIC value for both Ag NPs was indicated to be identical as 9. 37ppm for P. aeruginosa and E., coli.