Production of Gold Nanoparticles by Spore Displayed Tyrosinase

Introduction: According to the applications of gold nanoparticle in electronic and medicine, green biological synthesis methods for gold nanoparticle synthesis are considered. Different biological methods cause variant types of metal nanoparticles. Enzymes are one of the powerful tools in this approach. In this study, the role of tyrosinase in gold nanoparticle synthesis was studied by spore displayed tyrosinase. Materials and methods: Bacillus subtilis spore displayed tyrosinase developed in our previous work, was used as an enzyme source for synthesis of Au nanoparticles (AuNPs). Xray diffraction technique and transmission electron microscopy were used to characterize the nanoparticles. To confirm the role of enzyme in AuNPs synthesis, two types of tyrosinases from Bacillus megaterium and Streptomyces also were studied. Results: The results revealed that AuNPs were produced due to reducing Au3+ to Au0 by spore displayed tyrosinase. These biogenic nanoparticles showed mixed structures including spherical, triangular and hexagonal with the approximate size 2.5 to 35 nm. Furthermore, purified Bacillus megaterium tyrosinase and Streptomyces tyrosinase also produced AuNPs. Discussion and conclusion: The supposed mechanism of Au nanoparticle synthesis by tyrosinase, is electron transferring from copper ions to Au3+. The results represent a green environmental friendly simple method in synthesis AuNPs by spore displayed tyrosinase.