Eight fungal species were screened for mycosynthesis of silver nanaoparticles (AgNPs), by visual observation of fungal filtrate only six fungal species were found to reduce the silver salt into silver nanoparticles. The UV-visible spectra of the biosynthesized nanoparticles (AgNPs) by Aspergillus ochraceus (RCMB 036254) cell filtrate showed characteristic surface plasmon absorption at 420 nm. Transmission electron microscopy (TEM) micrograph showed the formation of spherical AgNPs ranging from 5.5 to 24.5 nm diameter. The Qualitative, as well as quantitative status of elemental silver was characterized by Energy Dispersive Analysis of X-ray (EDX). The optimum conditions for maximum production of AgNPs were obtained using 0.75 mM silver nitrate at 40°C and pH 6. The antimicrobial activity of the mycosynthesized nanoparticles under optimum conditions were investigated alone and in combination with commonly used antibiotics against Methicillin-resistant Staphylococcus aureus (MRSA). Out of thirteen commonly used antibiotics, the antibacterial efficiency of only five antibiotics has been increased as a result of combination with AgNPs. Biosynthesized silver nanoparticles showed dose-dependent antitumor activity with IC50 at 1.4, 2.1, and 1.2 µg/ml against human colon carcinoma, human breast cancer and human hepato-cellular carcinoma cells, respectively, while 39.6 µg/ml was required to induce 50% of normal Vero cell mortality.
Key words: Biosynthesis, silver nanoparticles, mycosynthesized silver nanoparticles
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