Sustainable green synthesis of silver nanoparticles using Sambucus ebulus phenolic extract (AgNPs@SEE): Optimization and assessment of photocatalytic degradation of methyl orange and their in vitro antibacterial and anticancer activity

The biogenic approach in the synthesis of nanoparticles provides an efficient alternative to the chemical synthesis system. Furthermore, the ecofriendly synthesis of metallic nanoparticles is developing rapidly due to its wide applications in sciences. In this research, metallic silver nanoparticles (AgNPs) were biosynthesized using Sambucus ebulus (S. ebulus; AgNPs@SEE) extract for the evaluation of efficient antibacterial, anticancer, and photocatalyst activities. The reaction parameters including temperatures, contact time, and AgNO₃ concentration were discussed and optimized. The optimized nanoparticles (AgNPs@SEE) showed cubic structure, spherical morphology with the average size of 35–50 nm. The photocatalytic performance of AgNPs was assessed by degradation of methyl orange at different concentrations of AgNPs@SEE (10 and 15 µl) under sun-light irradiation. About 95.89% of the pollutant was degraded (after 11 min), when 10 μl of nanocatalyst used. Also, the degradation of contaminant increased (about 95.47% after 7 min) by increasing the nanoparticle concentration to 20 μl. All in all, the results showed that the percentage of pollutant degradation increased with increasing the concentration of nanocatalyst. Furthermore, anticancer activity of AgNPs@SEE on human cancer cell lines (AGS and MCF-7), and antibacterial activity on both Gram-positive and Gram-negative microorganisms were studied. The synthesized AgNPs@SEE exhibited superior performance on cancer cell lines and effective antibacterial properties against Gram-positive microorganisms (like MIC value of 1.5 µg/ml for S. aureus) than Gram-negative microorganisms. All these investigations revealed that silver nanoparticles synthesized by natural extract have the potential to use as low-cost and efficient nanoparticles for environmental and biomedical applications.     

Green synthesis of silver nanoparticles using olive leaf extract and its antibacterial activity

The silver nanoparticles (AgNPs) synthesized using hot water olive leaf extracts (OLE) as reducing and stabilizing agent are reported and evaluated for antibacterial activity against drug resistant bacterial isolates. The effect of extract concentration, contact time, pH and temperature on the reaction rate and the shape of the Ag nanoparticles are investigated. The data revealed that the rate of formation of the nanosilver increased significantly in the basic medium with increasing temperature. The nature of AgNPs synthesized was analyzed by UV–vis spectroscopy, X-ray diffraction, scanning electron microscopy and thermal gravimetric analysis (TGA). The silver nanoparticles were with an average size of 20–25 nm and mostly spherical. The antibacterial potential of synthesized AgNPs was compared with that of aqueous OLE by well diffusion method. The AgNPs at 0.03–0.07 mg/ml concentration significantly inhibited bacterial growth against multi drug resistant Staphylococcus aureus (S. aureus), Pseudomonas aeruginosa (P. aeruginosa) and Escherichia coli (E. coli). This study revealed that the aqueous olive leaf extract has no effect at the concentrations used for preparation of the Ag nanoparticles. Thus AgNPs showed broad spectrum antibacterial activity at lower concentration and may be a good alternative therapeutic approach in future.     

Studies on green synthesized silver nanoparticles using Abelmoschus esculentus (L.) pulp extract having anticancer (in vitro) and antimicrobial applications

Silver nanoparticles (Ag NPs) were successfully synthesized using AgNO₃ via an eco-friendly and simple green route using Abelmoschus esculentus (L.) pulp extract at room temperature. The phytochemicals present in A. esculentus (L.) pulp extract were used both as a reducing and a stabilizing agent for the synthesis of Ag NPs. The stabilization of Ag NPs with phytochemicals was justified using Fourier-transform infrared spectroscopy. The size of the as-synthesized Ag NPs was examined using dynamic light scattering and confirmed by transmission electron microscopy. The crystalline nature of Ag NPs had been identified using X-ray diffraction. The present study demonstrated the efficacy of Ag NPs against Jurkat cells in vitro. Our study also showed that the IC₅₀ dose of Ag NPs leads to the increase in intracellular reactive oxygen species and significantly diminished mitochondrial membrane potential, indicating the effective involvement of apoptosis in cell death. The synthesized Ag NPs also exhibited good antimicrobial activity against different gram class bacteria.     

Green biosynthesis and characterization of zinc oxide nanoparticles using Corymbia citriodora leaf extract and their photocatalytic activity

ABSTRACT

We reported a green and simple method for biosynthesizing zinc oxide nanoparticles (ZnO NPs) using Corymbia citriodora leaf extract as reducing and stabilizing agent. SEM, EDX, XRD, UV–VIS spectroscopy, Raman spectroscopy and TGA have been used for characterizing the biosynthesized ZnO NPs. The results indicating the ZnO NPs synthesized by C. citriodora leaf extract have high purity and the average size is 64?nm. The photocatalytic activity of the ZnO NPs has been investigated by degradation methylene blue under visible light irradiation. Due to the smaller size, the biosynthesized ZnO NPs showed an excellent photocatalytic performance.     

Phytogenic fabrication of iron oxide nanoparticles and evaluation of their in vitro antibacterial and cytotoxic activity

Several metal-based nanoparticles (NPs) have been found to be toxic and are known to exert adverse health outcomes with irreversible side effects. This highlights the need to discover effective, stable, and biocompatible therapeutic components using natural sources. Here, a hexane extract of Nigella sativa seeds was used to synthesize iron oxide NPs (NS-IONPs) embedded with N. sativa phytoconstituents. The extract acted as a reducing agent that restricted the size of the NS-IONPs to 5–6 nm, signifying the potential to be cleared through the renal system. The fabricated NS-IONPs had a prominent effect on pathogenic gram-negative bacteria, E. coli (19.3 mm) and Salmonella typhi (14.2 mm) and lung cancer cells (lowest IC₅₀ of 18.75 µg/mL) mainly by binding to the phospholipid components of the cell membrane. This resulted in cell shrinkage and further inhibited cell growth. Transmission electron microscopy analyses revealed that the mechanisms of cellular NP uptake varied depending on the cell type. Accumulation of NS-IONPs inside the cell increased BAX expression and arrested the cells at the G0/G1 phase, thereby conspicuously extending the G0 phase to initiate necrosis. Thus, these finding suggest that the synthesized NS-IONPs exhibited high antibacterial activity and effective cytotoxicity against cancer cell lines A549 and HCT116 compared to IONPs. The innovation of the current study is that the biogenic fabrication of IONPs is simple and cost effective results in stable nanomaterial, NS-IONPs with potential antibacterial and anticancer activity, which can be explored furthermore for various biomedical applications.