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In this study, silver nanoparticles (AgNPs) were synthesized in an environmentally friendly manner using plant extracts from Luisia tristis. The formation of the nanoparticles was confirmed by a reddish-brown colour change and further characterized using ultraviolet–visible (UV–Vis), Fourier transform infrared spectrometer (FTIR), scanning electron microscope (SEM), and transmission electron microscope (TEM) techniques. The average size of the particles was found to be 16–48 nm. The antimicrobial activity of the AgNPs was evaluated against harmful bacteria and compared to the commonly used antibiotic ciprofloxacin. The AgNPs were found to be highly effective, with a 24 mm zone of inhibition against Escherichia coli, and more effective than ciprofloxacin. Additionally, a minimum inhibitory concentration assay was performed with a concentration of 100 mg/mL of AgNPs, which were found to effectively inhibit the growth of selected pathogens. Overall, the study demonstrates the potential for using plant-derived AgNPs as a natural and eco-friendly alternative for antimicrobial and antioxidant applications. This method is a fast, cost-effective way to generate silver nanoparticles at room temperature and may be useful in creating environmentally friendly antibacterial solutions for biomedical applications.

Green nanotechnology involves the synthesis of nanoparticles without the involvement of toxic chemicals. The present study reports the green synthesis of silver nanoparticles from Annona squamosa leaf extract rapidly within 20 min. High throughput characterization such as UV-vis spectroscopy, Fourier Transform-Infrared Spectroscopy (FT-IR), Transmission Electron Microscopy (TEM), Field Emission-Scanning Electron Microscopy (FE-SEM), X-ray diffraction (XRD) and Zeta potential measurements disclose the existence of silver nanoparticles. The phenolic compounds present in the aqueous leaves extract paves way for the possible reduction of silver to nano-silver. Electron microscopic studies revealed the average size of nanoparticles were 52 nm. The nanoparticles are highly stable by reaching a zeta potential value of −33.6 mV. Comparative antibacterial efficacy of silver nanoparticles was investigated by disk diffusion and microtitre broth dilution method against Escherichia coli. The result showed that silver nanoparticles are toxic to E. coli cells at higher concentration. Overall, we suggest microtitre broth dilution method is more reliable to determine the antimicrobial activity of silver nanoparticles than disk diffusion method.

Synthesis of nanomaterials by biological approach is innovative, cheaper and environmental friendly and requires less-labor. In this regard, the present study focused on the synthesis of silver nanoparticles from the extract of Sargassum tenerrimum. Synthesized silver nanoparticles were well-characterized by UV-Visible Spectroscopy (UV-Vis), Fourier-Transform Infra-red Spectroscopy (FT-IR), Transmission Electron Microscopy analysis (TEM) and Dynamic Light Scattering (DLS). It was found that spherical shaped nanoparticles of size 20 nm were found in TEM analysis and showed effective anti-bacterial activity against standard reference strains. Altogether, extracts from seaweed were screened for phytochemicals followed by FT-IR prediction to reveal chemical functional groups present. The results showed that the anti-bacterial activity of silver nanoparticles was comparably higher than the phytochemicals present. Therefore, the present study elucidates silver nanoparticles can play a vital role in nano-based therapy in future.