en ميکروب شناسي Microbiology تحقيقي Original Paper <strong>Background and objectives:</strong> Recycled polyethylene terephthalate (RPET) nanofibers have become an important part of human life, with a continuous increase in their production and consumption. Herein, the antibacterial activity of nickel nanoparticles/recycled polyethylene terephthalate nanofibers (NiNP/RPET NF web) was evaluated by analyzing alginate expression in <em>Pseudomonas aeruginosa</em>, as an opportunistic microorganism.<br> <strong>Methods:</strong> NiNPs were synthesized and NiNP/RPET NF was produced by adding 25 &mu;g/ml of NiNP to 10% solutions of RPET at a weight ratio of 3%. After exposing <em>P. aeruginosa</em> (PA01) to NiNP/RPET NF, the biofilm-forming capacity was determined and real-time PCR was performed to measure <em>algD</em> expression.<br> <strong>Results:</strong> Treatment with 25 &mu;g/ml of NiNP/RPET NF reduced growth of <em>P. aeruginosa</em> on Mueller Hinton agar but did not result in complete inhibition. The biofilm optical density (550 nm) was 0.464 &plusmn; 0.021 after treatment with NiNP/RPET NF and 0.082&plusmn; 0.011 in the absence of NiNP/RPET NF. This indicates the significant reduction of biofilm formation after exposure to NiNP/RPET NF (p=0.01). In addition, a 0.6-fold (p=0.03) reduction in alginate expression was detected by real-time quantitative real-time PCR.<br> <strong>Conclusion:</strong> Our results indicate the potential of NiNP/RPET NF for application in nano-based antibacterial medical systems. Nickel nanoparticles, polyethylene terephthalate, recycling, Pseudomonas aeruginosa, Alginate 21 26 http://mlj.goums.ac.ir/browse.php?a_code=A-10-997-1&slc_lang=en&sid=1 Mohammad Hassan Jokar jokarmh@mums.ac.ir 100319475328460021816 100319475328460021816 No Golestan Rheumatology Research Center, Sayad Shirazi Hospital, Golestan University of Medical Sciences, Gorgan, Iran Fatemeh Mohamadkhani fmohammadkhani@yahoo.com 100319475328460021817 100319475328460021817 No Department of Textile Engineering, Functional Fibrous Structures & Environmental Enhancement (FFSEE), Amirkabir University of Technology, Tehran, Iran Maliheh Moradzadeh moradzadeh63@yahoo.com 100319475328460021818 100319475328460021818 No Golestan Rheumatology Research Center, Sayad Shirazi Hospital, Golestan University of Medical Sciences, Gorgan, Iran Samira Beygi samirabyg@gmail.com 100319475328460021819 100319475328460021819 No Department of Biology, Science and Research Branch, Islamic Azad University, Tehran, Iran Ashraf Mohamadkhani ashraf_mohamadkhani@yahoo.com 100319475328460021820 100319475328460021820 Yes Liver and Pancreatobiliary Diseases Research Center, Digestive Disease Research Institute, Shariati Hospital, Tehran University of Medical Sciences, Tehran, Iran