The present study reports that the biosynthesis of AgNPs using an endophytic fungus isolated from the ethnomedicinal plant Centella asiatica. The endophytic fungus was identified as Aspergillus versicolor ENT7 based on 18S rRNA gene sequencing (NCBI Accession number KF493864). The AgNPs synthesized were characterized by UV–visible spectroscopy, Fourier transform infra-red spectroscopy (FTIR), transmission electron microscopy (TEM), X-ray diffraction (XRD), particle size analyzer, and zeta potential measurements. The UV–Vis absorption spectra showed the peak at 429 nm which confirmed the synthesis of AgNPs. TEM analysis revealed that the AgNPs were spherical in shape with 3–40 nm in size; similar results were also obtained by Horiba particle size analyzer with 5–40 nm in size. The synthesized AgNPs were highly stable due to their high negative zeta potential value of −38.2 mV. XRD studies showed (111), (200), (220), (311), and (222) planes of the face-centered cubic (FCC) lattice, indicating the crystalline nature of the AgNPs. Selected area electron diffraction (SAED) pattern of the AgNPs showed five circular fringes which were in accordance with XRD data and confirmed the formation of high crystalline nature of AgNPs. FTIR measurements indicated the peaks at 3273, 2925, 1629, 1320, and 1020 cm⁻¹ corresponding to different functional groups possibly involved in the synthesis and stabilization of AgNPs. The synthesized AgNPs exhibited effective free radical scavenging activity with the IC50 value of 60.64 µg/ml. The synthesized AgNPs were found to be highly toxic against both gram-positive and gram-negative bacteria and also showed a very good antifungal activity.

The present study reports the simple and eco-friendly approach for biosynthesis of silver nanoparticles (AgNPs) using aqueous callus extract as reducing agent for the first time. The formation of AgNPs was initially confirmed by characteristic surface plasmon resonance (SPR) peak 453 nm by UV–Visible spectroscopy. FTIR spectrum shows different functional groups which probably involved in the synthesis and stabilization of AgNPs. TEM analysis determined the well-dispersed AgNPs with roughly spherical shape and size ranging 5–40 nm. XRD patterns revealed the crystalline nature of AgNPs with face-centered cubic (fcc) lattice. The synthesized AgNPs were found to have strong inhibitory activity against Staphylococcus aureus, Bacillus subtilis, Escherichia coli, Pseudomonas aeruginosa.

In the present study, green synthesis of silver nanoparticles (AgNPs) was performed using flower extracts of Aerva lanata (Al) from Amaranthaceae family. The size, shape, and elemental composition of the silver nanoparticles (AgNPs) was studied using transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), and UV-visible spectroscopy. The dynamic light scattering (DLS), of silver nanoparticles (AgNPs) exhibited mean size of 7.6 nm in the range of 5–15 nm, having a poly-dispersed indexed value of 0.419. Zeta potential contributing to the stability of silver nanoparticles was recorded as −18.7 mV. Transmission electron microscopy (TEM) and energy dispersive X-ray (EDX) analysis confirmed the presence of the synthesized AgNPs with an average size range 7 ± 3 nm. The biosynthesized silver nanoparticles displayed antibacterial activity against Gram-positive and Gram-negative bacteria. The 2,2’-Diphenyl-1-picrylhydrazyl (DPPH) radical scavenging assay revealed antioxidant potential of silver nanoparticles in the concentration of 100 µg/ml. The photocatalytic activity of silver nanoparticles was evaluated using decolourization of the dyes under the sunlight using UV-Vis. spectroscopy. The results suggest that biosynthesized silver nanoparticles from A. lanata (Al-AgNPs) flower extracts have broad spectrum antibacterial, antioxidant and catalytic activities may be useful in a variety of biomedical and industrial applications. Graphical Abstract

The present study reports the biosynthesis of silver nanoparticles (IH-AgNPs) using aqueous leaf extract of Indigofera hisruta L. The biosynthesized IH-AgNPs were found to be FCC crystals, 5–10 nm in size, spherical in shape and stable. The biosynthesized IH-AgNPs showed dose-dependant cytotoxicity against prostate cancer (PC3) (IC₅₀ = 68.5 μg/mL), colon cancer (COLO205) (IC₅₀ = 85.2 μg/mL), and mouse melanoma (B16F10) (IC₅₀ = 80.9 μg/mL). IH-AgNPs were found to be nontoxic towards normal CHO (Chinese hamster ovary) cells. The biosynthesized IH-AgNPs showed effective in vitro antioxidant activity against DPPH (IC₅₀ = 63.43 μg/mL) and H₂O₂ (IC₅₀ = 89.93 μg/mL) radicals. IH-AgNPs exhibited effective antibacterial activity against both Gram+ve and Gram-ve bacteria. MIC values of IH-AgNPs against S. aureus, B. subtilis, P. aeruginosa and E. coli were found to be 7.8 μg/mL, 3.9 μg/mL, 15.6 μg/mL and 15.6 μg/mL respectively. IH-AgNPs also showed inhibitory activity against fungal pathogens including C. albicans, C. nonalbicans and C. tropicalis. Considering the results together, we demonstrate that IH-AgNPs exhibits three different bioactivities (3-in-1 system) and they could be employed as future antimicrobial, antioxidant and anticancer agents/drug delivery vehicles in the field of biomedicine.