In this study, crude extracellular keratinase obtained from a novel keratin-degrading bacterial strain, Bacillus safensis LAU 13 (GenBank accession No. KJ461434) was used for the synthesis of silver nanoparticles (AgNPs). The particles were characterised by UVVisible spectroscopy, Fourier transform infrared (FTIR) spectroscopy, and transmission electron microscopy. The biosynthesised AgNPs exhibited maximum absorbance at 409 nm. They are spherical in shape with the size ranging 5-30 nm. The FTIR spectrum showed peaks at 3410, 2930, 1664, 1618, 1389 and 600 cm -1 , indicating that proteins were the capping and stabilisation molecules in the synthesis of AgNPs. Data obtained from XRD showed that the particles have face-centred cubic phase and are crystalline in nature with average size of *8.3 nm. The particles showed effective inhibitory activity against five clinical isolates of Escherichia coli. Therefore, the keratinase of this strain could be used to develop an environmental friendly method for the rapid synthesis of AgNPs. To the best of our knowledge, this is the first report of green synthesis of AgNPs using the metabolite of B. safensis, and the report adds to the growing relevance of B. safensis as a potential industrially viable organism.

This work reports the biogenic synthesis of silver nanoparticles (AgNPs) using the pod extract of Cola nitida, the evaluation of their antibacterial and antioxidant activities, and their application as an antimicrobial additive in paint. The AgNPs were characterized with UV-Vis spectroscopy, Fourier-transform infrared (FTIR) spectroscopy, and transmission electron microscopy (TEM). The AgNP solution was dark brown with a maximum absorbance occurring at 431.5 nm. The FTIR spectrum showed strong peaks at 3336.85, 2073.48, and 1639.49 cm −1 , indicating that proteins acted as the capping and stabilization agents in the synthesis of the AgNPs. The AgNPs were spherical, with sizes ranging from 12 to 80 nm. Energy dispersive X-ray (EDX) analysis showed that silver was the prominent metal present, while the selected area electron diffraction pattern conformed to the face-centred cubic phase and crystalline nature of AgNPs. At various concentrations between 50 and 150 g/ml, the AgNPs showed strong inhibition of the growth of multidrug resistant strains of Klebsiella granulomatis, Pseudomonas aeruginosa, and Escherichia coli. In addition, at 5 g/ml, the AgNPs completely inhibited the growth of Staphylococcus aureus, Escherichia coli, Pseudomonas aeruginosa, Aspergillus niger, A. flavus and A. fumigatus in a paint-AgNP admixture. The AgNPs exhibited a potent antioxidant activity with an IC 50 of 43.98 g/ml against 2,2-diphenyl-1-picrylhydrazyl and a ferric ion reduction of 13.62-49.96% at concentrations of 20-100 g/ml. This study has

In this study, spider cobweb as a novel biomaterial was used for the green synthesis of silver nanoparticles (AgNPs). The synthesized AgNPs were characterized using UV-Vis spectroscopy, Fourier-transform infrared spectroscopy (FTIR), and transmission electron microscopy. The efficacy of biosynthesized particles as antibacterial agents was evaluated using multidrug resistant clinical bacterial isolates through sensitivity testing with AgNPs and combination of AgNPs with some selected antibiotics. In addition, the potential application of the particles as additives in paints was demonstrated using some bacterial and fungal isolates. The synthesized AgNPs which were dark brown in color displayed maximum absorbance at the wavelength of 436 nm. It was observed that the reaction mixture of 1:40 (extract:AgNO 3 solution) at pH of 8.5 produced particles with maximum absorbance at 436 nm. The FTIR spectrum showed peaks at 3298, 2359, 2089, and 1635 cm -1 , indicating that proteins were the capping and stabilization molecules in the synthesis of AgNPs. The particles were spherical in shape with size ranging about 3-50 nm. The energy-dispersive X-ray analysis showed the presence of silver as the most prominent metal, while the selected area electron diffraction pattern conformed to the face-centered cubic phase and crystalline nature of AgNPs. The AgNPs inhibited the growth of several bacterial isolates including S. aureus, E. coli, Klebsiella granulomatis and P. aeruginosa in the range of 10-17 mm at concentration of 100 lg/ml. It was also demonstrated that AgNPs potentiated the activities of augmentin, ofloxacin and cefixime in the AgNP-antibiotic synergy studies. Similarly, the inclusion of AgNPs as additive in white emulsion paint led to the total inhibition of growth of E. coli, P. aeruginosa, Aspergillus niger and A. fumigatus. To the best of our knowledge, this is the first report of the use of cobweb for the green synthesis of AgNPs. The immense antimicrobial activities of the particles can be explored in the creation of novel products, where it can be used as additive to protect materials against microbial attack.

In this study, seed and seed shell extracts of Cola nitida were investigated for the biogenic synthesis of silver nanoparticles (AgNPs) under ambient condition. The biosynthesized AgNPs were characterized through visual development of colour, UV-vis spectroscopy, Fourier transform infrared spectroscopy (FTIR) and transmission electron microscopy (TEM). The antibacterial activities of the AgNPs were determined using some multidrug-resistant clinical isolates. The biosynthesized AgNPs depicted brown and yellowish orange colour using seed and seed extract, respectively, with maximum absorbance readings at 457.5 and 454.5 nm. The FTIR spectrum showed strong peaks at 3292.49, 2086.98 and 1631.78 cm −1 for seed extract-mediated AgNPs, while peaks of 3302.13, 2086.05 and 1633.71 cm −1 were obtained for seed shell extract-mediated AgNPs, all indicating that proteins were the capping and stabilization molecules in the biogenic synthesis of AgNPs. The AgNPs were spherical in shape with sizes ranging from 8 to 50 and 5 to 40 nm for seed and seed shell-mediated AgNPs, respectively. The energydispersive X-ray (EDX) analysis showed the presence of silver as a prominent metal, while the selected area electron diffraction (SAED) pattern conformed to the face-centred cubic phase and crystalline nature of AgNPs. At various concentrations ranging from 50-150 μg/ml, the AgNPs inhibited growth of multidrug-resistant strains of Klebsiella granulomatis, Pseudomonas aeruginosa and Escherichia coli to the tune of 10-32 mm. Comparatively, seed shell extractmediated AgNPs had better activities with minimum inhibitory concentration (MIC) of 50 μg/ml against all the tested isolates, while the MICs of seed extract-mediated AgNPs were obtained as 50, 80 and 120 μg/ml against E. coli, P. aeruginosa (wound) and P. aeruginosa (burn), respectively. This study has demonstrated the feasibility of eco-friendly biogenic synthesis of AgNPs using seed and seed shell extracts of C. nitida, and the report to the best of our knowledge is the first reference to extracts of C. nitida for the green synthesis of AgNPs.

This study investigated the green biosynthesis of gold (Au) and silver-gold alloy (Ag-Au) nanoparticles using cell-free extract of Bacillus safensis LAU 13 strain (GenBank accession No: KJ461434). The biosynthesized AuNPs and Ag-AuNPs were characterized using UV-Vis spectroscopy, Fourier-transform infrared spectroscopy, and transmission electron microscopy. Evaluation of the antifungal activities, degradation of malachite green, anti-coagulation of blood, and thrombolysis of human blood clot by the biosynthesized nanoparticles were investigated. The AuNPs and Ag-AuNPs had maximum absorbance at 561 and 545 nm, respectively. The FTIR peaks at 3318, 2378, 2114, 1998, 1636, 1287, 446, 421 cm for AuNPs; and 3310, 2345, 2203, 2033, 1636, 1273, 502, 453, 424 cm for Ag-AuNPs indicated that proteins were the capping and stabilization molecules in the biosynthesized nanoparticles. The particles were fairly spherical in shape with size of 10-45 nm for AuNPs and 13-80 nm for Ag-AuNPs. Moreover, energy dispersive X-ray analysis of AuNPs revealed gold as the most prominent metal in the AuNPs solution, while silver and gold were the most prominent in the case of Ag-AuNPs. Selected area electron diffraction showed the biosynthesized nanoparticles as crystal structures with ring shape pattern. AuNPs and Ag-AuNPs displayed growth inhibitions of 66.67-90.78% against strains of Aspergillus fumigatus and A. niger at concentration of 200 μg/ml , and remarkable degradation (> 90%) of malachite green after 48 h. Furthermore, the nanoparticles prevented coagulation of blood, and also completely dissolved blood clots, indicating the biomedical potential of AuNPs and Ag-AuNPs in the management of blood coagulation disorders. This is the first report of the synthesis of AuNPs and Ag-AuNPs using a strain of B. safensis for biomedical and catalytic applications.