Mycosynthesis of bactericidal silver and polymorphic gold nanoparticles: physicochemical variation effects and mechanism

AIM: Extracellular synthesis of silver and gold nanoparticles using aqueous cell-free filtrate (CFF) of endophytic Chaetomium globosum and characterization of its bioactive proteins. METHODS: Temperature and pH gradients were used to assess their effects on dimensions of NPs. NPs were tested in vivo for antibacterial activity. MALDI-TOF-MS/MS was used for characterization of CFF proteins. RESULTS: Fungal CFF fabricated nanoparticles of various shape under varied physicochemical conditions. Silver nanoparticles showed significantly (p ≤ 0.5) enhanced antibacterial activity against Staphylococcus aureus and Klebsiella pneumoniae compared with AgNO3. Two prominent CFF proteins showed homology with benzoate 4-monooxygenase cytochrome P450 and ubiquinol-cytochrome c reductase. CONCLUSION: The study achieved controlled mycosynthesis of NPs and explains the hitherto poorly known mechanism of reduction, stabilization and antibacterial activity of nanoparticles.