Antibacterial Activity of Silver Nanoparticles Using Ulva fasciata Extracts as Reducing Agent and Sodium Dodecyl Sulfate as Stabilizer

Green Synthesis of Silver Nanoparticles Using Datura metel Flower Extract Assisted by Ultrasound Method and Its Antibacterial Activity

BACKGROUND

Green synthesis method of nanoparticles has been developed for several years. Besides providing environmental-friendly process, green synthesis of nanoparticles using plant extract provides synergistic effect of the secondary metabolite in such antibiotic activity. The study with an intensification process in nanoparticles formation is also gaining great attention. This research deals with the green synthesis of silver nanoparticles using Datura metel flower extract for the antibacterial agent. The use of ultrasound-assisted method for the synthesis was investigated.

METHODS

Synthesis of silver nanoparticles (AgNPs) using Datura metel flower extract under ultrasound- assisted method has been conducted. Evaluation of the successful synthesis was done using UV-visible spectrophotometry, particle size analyzer, x-ray diffraction, and transmission electron microscopy. The prepared AgNPs were tested as an antibacterial against S. aureus, K. pneumoniae, S. pyogenes, and E. coli.

RESULTS

The ultrasound-assisted synthesis of AgNPs produces particles ranging from 25-70 nm in size; meanwhile, the reflux method demonstrated the size of 50-170 nm. These particles size represents the effect on the antibacterial activity as the ultrasound-assisted synthesized Ag NPs have higher inhibition zone towards all tested bacteria. Subsequently, these data presented the applicability of Ag NPs synthesis using an ultrasound method as a potential candidate for biomedical applications.

CONCLUSION

The profile of UV-Visible spectra and particle size analyses demonstrated the applicability of the ultrasound technique to produce a smaller size of the nanoparticles with higher antibacterial activity.

Ulvan as a Reducing Agent for the Green Synthesis of Silver Nanoparticles: A Novel Mouthwash

The antibacterial activity of an Ulvan-based silver nanoparticle (AgNP) system was evaluated in the current study. The green synthesis of biogenic silver nanoparticles was conducted using Ulvan, a sulphated polysaccharide extracted from Ulva lactuca. A novel mouthwash containing AgNPs was prepared, and tested for its efficacy and safety. AgNPs were confirmed with spectrophotometric analysis (UV–A visible spectrophotometer), and the characterisation was established with Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD), and transmission electron microscopy (TEM). The AgNPs were spherical, and their average size was 8–33 nm, as shown via TEM. The antioxidant assay was conducted via DDPH assay, wherein the AgNPs, at a concentration of 50 μL/mL, showed 93.15% inhibition. Furthermore, anticancer activity was tested by evaluating the cell viability utilising the method of an MTT assay on the 3T3-L1 cell lines. AgNPs, at 30 µL/mL, showed maximal cell viability, denoting no cytotoxic effect. The silver-nanoparticle-based mouthrinse, at a concentration of 100 µL/mL, demonstrated antimicrobial activity against Streptococcus mutans, Staphylococcus aureus, Lactobacillus, and Candida albicans. This study shows that mouthwash prepared from the Ulvan-silver nanoparticle system could be a nontoxic and effective oral antimicrobial agent.

Biogenic and characterizations of new silver nanoparticles stabilized with indole acetic acid derived from Azospirillum brasilense MMGH-SADAT1, their bioactivity, and histopathological assessment in rats

An Egyptian rhizobacterium Azospirillum sp. isolated from Sadat city was able to produce indole acetic acid (IAA) up to (30.59 µg/ml). The isolate was identified biochemically and by 16S rRNA sequencing which showed 99.9% similarity to Azospirillum brasilense. The new isolate has been registered in Genbank with accession number MH179119.1. Extracted IAA was used as reducing or stabilizing agent of sliver nanoparticles (AgNPs). Successful fabrication of biogenic IAA-AgNPs was confirmed by Fourier Transform Infrared Spectrophotometer (FTIR) analysis of IAA which showed absorbance peak at 3434.78 cm^-1 due to the N-H stretch of primary amines. Highly resolution Transmission Electron Microscopy (HR-TEM) showed AgNPs coating or capping with IAA in spherical shaped with size ranged from 6.01 to 44.02 nm. Energy dispersive X-ray (EDX) analysis revealed that Ag⁺ ions were attached to the surface of IAA-AgNPs particles. HR-TEM examination showed cell wall damage of Citrobacter freundii cells after exposure to IAA-AgNPs leading to cell death. In vivo results showed that C. freundii infection of rats induced significant increase in liver and kidney functions and deleterious histopathological alteration in rat's tissues. However, treatment by extracted IAA and IAA-AgNPs could normalize the biochemical and histopathological alterations occurred in infected rats. This is the first study to prove that IAA extracted from Azospirillum brasilense is a hopeful capping agent for NPs which has potential to protect against pathogenic infections, nontoxic and/or safe on rat's metabolisms.

Green synthesis of silver nanoparticles with algae and the importance of capping agents in the process

BACKGROUND

Nanoparticle synthesis is a very interesting area of research currently due to the wide applications of nanoparticles. The nanoparticles have a diameter ranging between 1 and 100 nm and they are used in different fields like electronics, pharmaceuticals, cosmetics, biotechnology, medicines, etc. Nanoparticles have gained the interest of researchers due to their large surface-to-volume ratio and their capability to interact effectively with other particles. Several different methods can be used for the production of silver nanoparticles (AgNPs) including chemical, physical, and biological. Out of all the methods, the biological method is considered the cleanest and safest as no toxic chemicals are used in the process. The biological method includes the use of bacteria, fungi, algae, and plant extract for the synthesis. Algal synthesis of AgNPs is especially interesting because of the high capacity of the algae to take in metals and reduce metal ions. Algae is a widely distributed organism and its availability is abundant; an added advantage is their growth under laboratory conditions. These organisms can help in large-scale production at a low cost.

SHORT CONCLUSION

This review article explains the different factors that should be considered for the effective synthesis of AgNPs using algae. Capping agents also affect the stability of nanoparticles. It also sheds light on the importance of capping agents in the synthesis of AgNPs. Alga-mediated synthesis of AgNPs along with the use of different capping agents can help in modulating the stability and size of the nanoparticles, thereby improving its cost-effectiveness and environment-friendly production.

Synthesis and Comparative Antibacterial Activity of Fatty Acid Capped Silver Nanoparticles

In the present work, the chemical reduction method has been used to synthesize silver nanoparticles using stearic acid capping agents in different concentrations. These nanoparticles are characterized by ultraviolet-visible spectroscopy and dynamic light scattering (DLS). The size of the synthesized silver nanoparticles found between 80-100 nm and stable up to 5 months. These nanoparticles show a very good bactericidal influence on E. coli and S. aureus. In this method silver nanoparticles have synthesized at room temperature without using any inert atmosphere, this is the advantage of this method over others.

New Brush Copolymers as an Effective Dispersant for Stabilizing Concentrated Suspensions of Silver Nanoparticles

Silver nanopowders (nano-Ag) have extremely high surface energy and are generally difficult to have an effective dispersant for their dispersion stabilization. This study proposes two brush copolymers that show a strong preference for adsorption on the nano-Ag surface via their backbone, while their side chains extend into the dispersion solvent for particle stabilization. After adding only 5 wt % (based on the mass of nano-Ag) of the proposed dispersants, the nano-Ag particles can be stably suspended without settling for at least 2 months. Besides, 5 wt % of these dispersants can well stabilize at least 40 wt % nano-Ag dispersed in di(ethylene glycol) ethyl ether, which is a common solvent for conductive inks and pastes. For applications, a thin film cast using the dispersed nano-Ag shows greatly improved surface flatness as compared to that made without the dispersant, and a low electrical resistivity of 2 × 10^-5 Ω cm is obtained after the film is annealed at 170 °C for 20 min.