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Introduction and Aim: The Biosynthesis of Gold nanoparticles (Au NPs) is an eco-friendly, cost effective and nontoxic alternative to chemical and physical methods. In the present study synthesis of Au NPs was performed by using a fungi Penicillium sp. isolated from agriculture soil. Materials and Methods: Fungi was isolated from the agricultural field and inoculated into Sabouraud Dextrose broth and incubated at 28º C in a shaker at 180 rpm for 96 to 120 hours. After incubation, the fungal culture was filtered and centrifuged, obtained fungal cell free extracts treated with 1mM gold salt (HAuCl4). The synthesis of Au NPs was confirmed by UV–visible spectroscopy and particles size was measured using Dynamic Light Scattering (DLS). Haemolytic assay of Au NPs was carried out using Chicken RBCs and results measured at 540 nm in UV-visible spectrophotometer. To study catalytic activity, Bromothymol blue (BB) was subjected to reduction by using sodium borohydride (NaBH4, 5.28X10-2 M) in the presence of Au NPs. Then the color change was monitored by visual observation. Results: The synthesis of Au NPs was preliminary observed by a color change from yellow to purple and confirmed by a peak at 560 nm using a UV–visible spectroscopy. The DLS analysis showed that the Au NPs were poly-dispersed and size ranges from 130 to 150 nm. The biosynthesised Au NPs was studied for their biocompatibility and dye degradation properties. Conclusion: The obtained results revealed that biosynthesized Au NPs shows a minimum level of toxicity to chicken erythrocytes and good catalytic activity towards the degradation of hazardous dye bromothymol blue. These nanoparticles could be potentially useful in various applications in medical and environmental fields.

Vanillin and its derivative, (4-((E)-(4-hydroxy-2-methylphenylimino) methyl)-2-methoxyphenol (MMP) were showed clear inhibition of violacein and pyocyanin at sub-MICs indicating a possible quorum quenching effect of both the compounds. MMP was able to inhibit the biofilm formation in Pseudomonas aeruginosa PAO1 at 125 μg/mL (p < 0.05), while vanillin at 250 μg/mL (p < 0.05) indicating that they act against quorum sensing regulated biofilm formation. The inhibition of biofilm was confirmed by visualization through fluorescence microscopy followed by docking analysis of molecules against quorum sensing activator proteins. Caenorhabditis elegans survival assay revealed that vanillin and MMP were able to increase survival of C. elegans from P. aeruginosa PAO1 infection. The study showed that the potent features of the MMP and vanillin in inhibiting the quorum sensing regulated virulence and biofilm, which was proved in C. elegans infection model as well as molecular docking studies.

Nanoparticles of different sizes and shapes can be synthesized by physical and chemical methods. But these methods involve toxic ingredients and hazardous byproducts which may be potentially harmful to either environment or human health. Therefore in the present study, an eco-friendly simple biosynthetic route was used for the synthesis of gold nanoparticles (GNPs) using cell free extracts of Enterobacter aerogenes. The synthesis of GNPs was preliminary observed by color change and confirmed by a peak at 530–560 nm using a UV–visible spectroscopy. The crystalline nature of the GNPs was confirmed by X-ray diffraction. TEM image showed the size of GNPs in the range of 4–6 nm. The functional groups adhered on the surface of the GNPs was analyzed by FTIR. The variation of size, shape and dispersity with the varying gold salt concentration was studied. The synthesized GNPs exhibited good catalytic activity for the reduction of methylene blue by NaBH4.

The biosynthesis of nanoparticles is a cost effective, eco-friendly and non toxic alternative to physical and chemical methods. In the present study, we report a rapid and eco-friendly method for extracellular biosynthesis of gold nanoparticles (GNPs) using cell free extract of Staphylococcus epidermidis. In this method, the formation of GNPs is rapid as the reaction process completes within few minutes. The synthesis of GNPs was preliminary observed by colour change from pale yellow to pink red and confirmed by peaks at 545–550 nm using a UV–visible spectroscopy. Transmission electron microscopy (TEM) showed formation of well dispersed GNPs in the range of 20–25 nm. Fourier transform-infrared spectroscopy (FT-IR) was used to characterise the functional groups which might have played an important role in reduction and stabilisation of GNPs. The synthesised GNPs showed good catalytic activity for methylene blue degradation. This is the first to report on the rapid and ecofriendly method for the biosynthesis of GNPs by S. epidermidis.

The development of eco-friendly approach for the preparation of monodispersed gold nanoparticles (GNPs) has received much attention for their easy application. Most of the current methods involve known protocols which employ toxic chemicals and hazardous byproducts. This greatly limits their use in biomedical fields, particularly in clinical applications. Recent research has been focused on green synthesis methods to produce different nanoparticles with suitable commercial viability. The biosynthesis of monodispersed GNPs using the spent cultures of Klebsiella pneumoniae as reducing and stabilizing agent has been reported. The gold salt concentration to improve monodispersity and stability of GNPs has been optimized. Synthesized GNPs were characterized by UV–Visible spectroscopy showed absorption spectra in the range of 530–560 nm at different concentrations of HAuCl4. At the optimum reaction concentration of 1.5 mM HAuCl4, absorption peak was obtained at 535 nm. The GNPs have been further characterized by X-ray diffraction, FTIR, DLS and TEM analysis. The DLS graph showed that the particles were more monodispersed. The TEM image showed the formation of spherical shaped GNPs in the range of 4–10 nm. The effect of gold salt concentration on dispersity, size and stability of the biosynthesized GNPs has been reported.

Introduction and Aim: Biosynthesis of metal nanoparticles is an important branch of nanobiotechnology. In recent years, microbial biosynthesis of nanoparticles is gaining importance due to its simplicity and eco-friendliness. Materials and Methods: In this study, Selenium nanoparticles (Se NPs) were synthesized by using the fungi Fusarium sp. isolated from agricultural soil. Mycosynthesized Se NPs were characterized by UV-Vis spectrometer and Dynamic Light Scattering (DLS) analysis. Further biosynthesized Se NPs screened for different biological activities such as antibacterial, antioxidant, hemolysis, cytotoxicity and catalytic activity. Results: Synthesis Se NPs was preliminary observed by a color change from pale yellow to orange red color and confirmed by UV peak at 342 nm. The DLS result shows the particles size ranges from 19 to 43 nm.The obtained result showed that the synthesized Se NPs possess good antibacterial activity against human pathogens such as E. coli, Staphylococcus aureus, Salmonella typhi and Klebsiella pneumonia. Further biogenic Se NPs showed less cytotoxicity on yeast cells and slight hemolysis. Conclusion: The synthesized Se NPs have good antioxidant property and antibacterial activity with less haemolytic property these properties lead to use of Se NPs in different biomedical applications. This Se NPs Also showed an efficient catalytic activity by degrading hazardous dyes such as methylene blue and bromothymol blue.