Tehran University of Medical Sciences Iranian Journal of Microbiology 2008-3289 15 5 2023 10 12 697 704 EN Mehrnaz Sheikh Hosseini Department of Biotechnology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran Zahra Moosavi-Nejad Department of Biotechnology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran Parisa Mohammadi Department of Microbiology, Faculty of Biological Sciences, Alzahra University, Tehran, Iran 2023 01 16 2023 09 27 Background and Objectives: With entering the “post-antibiotic era”, antibiotic resistance is one of the most important problems in food security, health and medicine. Invention of nanoparticles with intrinsic antimicrobial activity has been provided a new tool to combat the problem, including some metal nanoparticles. But protein nanoparticles have been often used as nano-carrier for antibiotic drugs, not for their own antibiotic activity. In this article we have fabricated a very small BSA-NP without any chemical modification on BSA molecules showing antibacterial activity. Materials and Methods: Bovine serum albumin nanoparticle (BSA-NP) was synthesized using botton-up approach, by dissolution of BSA in urea-containing Tris buffer for 60 min at 60°C. Then, the BSA solution was dialyzed against distilled water in order to nanoparticle formation. The resulted BSA-NP has been characterized by dynamic light scattering (DLS), field emission surface electron microscopy (FESEM), SDS-PAGE, Fourier transform infrared spectroscopy (FTIR) and UV-spectrophotometery. Minimum inhibitory concentration (MIC) method was used for evaluation of antibacterial activity of BSA-NP against Staphylococcus aureus and Pseudomonas aeruginosa. Results: The results obtained by DLS technique indicated that BSA molecules were self-assembled into small aggregates with a hydrodynamic diameter of 23.23 ± 2.1 nm. With a small polydispersity index (PDI=0.522), the nanoparticles had good spherical uniformity. The nanoparticles made from a single type of protein molecule (BSA) and have a relatively transparent appearance. The BSA-NPs caused a decrease in cell growth of both P. aeruginosa and S. aureus. Moreover, they had a bacteriostatic effect on P. aeruginosa (MIC=112×10-5 μM). Conclusion: In this study, using a green synthesis method, we succeeded in synthesizing a very small uniform BSA nanoparticles without any chemical modification on BSA molecules. It also has bacteriostatic properties against P. aeruginosa. Therefore, it is hypothesized that our BSA-NPs may be effective as a new approach to combat antibiotic resistance. https://ijm.tums.ac.ir/index.php/ijm/article/view/4086 https://ijm.tums.ac.ir/index.php/ijm/article/download/4086/1615