Biosynthesis of silver nano-particles by marine sediment fungi for a dose dependent cytotoxicity against HEp2 cell lines

Biosynthesis of silver nanoparticles has been carried out by using the cell free filtrate of marine sediment fungal species of Southern peninsular coastal region of India and identified based on the sequence analysis of Internal Transcribed Spacer region of rRNA genes. Species were identified as Aspergillus flavus SP-3, Trichoderma gamsii SP-4, Talaromyces flavus SP-5, and Aspergillus oryzae SP-6. The phylogenetic relationship between the fungal isolates and other fungal strains was compared. Treatment of silver nitrate with the fungal extract produced stable, predominant, monodispersed and spherical silver nanoparticles. Preliminary characterization revealed that the nano-particles were in the range of 20–60 nm in all the fungal isolates. Among all the fungi the silver nano-particles of T. gamsii SP-4 showed an enhanced antimicrobial activity against Gram positive bacteria, Gram negative bacteria and fungi pathogens; an anti-oxidant activity at an effective concentration of 99 µg/ml; and a dose dependent cytotoxic activity against HEp2 cell lines at LC50 value of 23 µg/ml. Thus, the strains, SP3, SP4, SP5, and SP6 could be used for simple, non-hazardous and efficient synthesis of antimicrobial and HEp2 cytotoxic silver nano-particles.