ABSTRACT

Nanoparticles is a refined particle ranging between 1 and 100 nanometres (nanometer). Microbial  biosynthesis of nanoparticles is a rapidly progressing area of nanobiotechnology. In this study Aspergillus floridensis  used for the extracellular biosynthesis of silver (Ag), gold (Au) and silver-gold composite  nanoparticles is reported.  This study synthesized eco-friendly, costeffective, and non-toxic Ag, Au, and Ag-Au composite NPs using the mycelia of   Aspergillus floridensis and applied the synthesized NPs for antimicrobial activities and to remediate waste petroleum products.  Polymerase Chain Reaction (PCR) and Internal Transcribed Spacer (ITS1/5.8S) rDNA techniques were used to characterize Aspergillus  floridensis. The Ag, Au and Ag-Au composite NPs synthesized by Aspergillus floridensis were characterized by UV–vis spectrophotometry FTIR and XRD. The UV-vis spectrophotometry was used to obverse the bioreduction properties of the Ag⁺ and Au⁺ NPs . FTIR and XRD were used for  the characterization of Ag, Au and Ag-Au composite NPs, For FTIR, The intensity of the NP peak revealed hydroxyl (OH) and carbonyl (C=O) groups formed by the capping of the carboxylic acid moieties. The XRD peaks were compared having the JCPDS card No (00-019-0701) as a facecentered cubic (FCC) crystal lattice structure.  The NPs formed revealed pores having tissue-like strands formed on the periplasmic surface of the mycelia of Aspergillus floridensis. The synthesized Ag and Au NPs showed antimicrobial activity against staphylococcus aureus. The remediation property of the NPs formed was revealed by the clearance of waste engine oil (WEO) on the surface of the agar medium. The synthesized NPs display potential for use in dermal creams and the remediation of petroleum products.