Silver (Ag) nanoparticles (NPs) were synthesized by pulsed laser (Nd:YAG, 1064 nm) ablation of individual target in various solutions. The influence of deionized water (DIW), ethanol and Polyvinylpyrrolidone (PVP) as ambient medium on the fundamental aspects such as ablation efficiency, particle size and stability of Ag NPs was studied. UV-vis spectrophotometer and transmission electron microscopy (TEM) were used to study the optical characterization and morphological analysis of all the synthesized samples, respectively. Preparation in DIW was carried out as a reference sample. The experiments demonstrated that ablation efficiency and stability of NPs in ethanol medium are lowest than those prepared in PVP medium and the reference sample. PVP medium led to higher stability, lower ablation efficiency and finer average particle size compared to reference sample.
This study examined the effect of varying concentrations of Ocimum basilicum aqueous extract, which was done via the green synthesis of Silver nanoparticles (AgNPs), on the identification of the most effective concentration for bacteria inhibitory activity. Different concentrations of the aqueous Ocimum basilicum extract (0.25, 0.50, 0.75 and 1.00 mM) were used as reducing and stabilizing agent to synthesize AgNPs by means of the reduction method. The crystal structure and morphology of the NPs were characterized UV–Vis spectra, X-ray diffraction (XRD) and scanning electron microscopy (SEM). The antibacterial efficacy of AgNPs was studied against E. coli ATCC 35218 using well diffusion, MIC, MBC, and time-kill curve. The dark yellow color of the Ocimum basilicum aqueous solution indicates the successful synthesis process of the AgNPs. UV-spectra of the AgNPs display a gradual increase of absorption in sequence with concentration increase of aqueous Ocimum basilicum extract solution from 0.25 to 1.00 mM. This, in turn, led to a shift in the wavelength from 488 to 497 nm, along with a change in the nanoparticle size from 52 to 8 nm. The tests also showed a high activity of the particles against bacteria (E. coli), ranging between 15.6 and 62.5 µg/ml. Based on AgNPs, it was confirmed that an aqueous Ocimum basilicum extract can be used as an effective, reducing and stabilizing agent for the synthesis of different sizes of AgNPs based on the solvent concentration. The AgNPs also proved to be effective in inhibiting and killing bacteria.
Our work was devoted to studying the effect of different concentrations of Mentha spicata aqueous extract on the green synthesis of silver nanoparticles (AgNPs) in order to obtain the most effective of these concentrations for bacteria inhibitory activity. Different concentrations of the aqueous M. spicata extract (0.25, 0.50, 0.75, and 1.00 mM) were used as biological solvent to synthesize AgNPs by means of the reduction method. The crystal structure and morphology of the NPs were characterized UV–vis spectra, X-ray diffraction (XRD), and scanning electron microscopy (SEM). The inhibition effect of AgNPs on Escherichia coli was studied to determine the minimum inhibitory concentration (MIC). The dark yellow color of the M. spicata extract aqueous solution indicates the successful synthesis of the AgNPs. UV spectra of the NPs show a gradual increase in absorption with increasing concentration of aqueous M. spicata extract solution from 0.25 to 1.00 mM, accompanied by a shift in the wavelength from 455 to 479 nm along with a change in the nanoparticle size from 31 to 9 nm. The tests also showed a high activity of the particles against bacteria (E. coli) ranging between 15.6 and 62.5 µg/ml. From the AgNPs, it was confirmed that aqueous M. spicata extract is an effective biosolvent for the synthesis of different sizes of AgNPs according to the solvent concentration. The AgNPs also proved effectual for the killing of bacteria.
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