Antibacterial activity of immobilized silver nanoparticles on TEPA-Den-SiO 2 against shrimp pathogen, Vibrio sp. Persian1 Mehrdad Sarkheil 1 , Iman Sourinejad 1 , Maryam Mirbakhsh 2 , Davood Kordestani 3 & Seyed Ali Johari 4 1 Faculty of Marine Science and Technology, University of Hormozgan, Bandar Abbas, Iran 2 Shrimp Hygiene and Diseases Department, Iran Shrimp Research Center, Bushehr, Iran 3 Department of Chemistry, Amirkabir University of Technology, Tehran, Iran 4 Fisheries Department, Natural Resources Faculty, University of Kurdistan, Sanandaj, Iran Correspondence: I Sourinejad, Faculty of Marine Science and Technology, University of Hormozgan, P.O. Box: 3995, Bandar Abbas, Iran. E-mail: sourinejad@hormozgan.ac.ir Abstract In this study, we prepared silver nanoparticles immobilized onto silica sand beads as an antibacterial material against pathogenic luminous Vibrio sp. Persian1. Silica beads were modified with 3-aminopropyltriethoxysilane (APTES), cyanuric chlorid and tetraethylene pen- tamine, and silver nanoparticles were generated in various concentrations (0.5, 1, and 2 mM g À1 of silica beads) of AgNO 3 on the surface using chemical reduction. Ag/TEPA-Den-SiO 2 samples were characterized by TEM, FE-SEM/EDS, FT-IR and ICP OES and their antibacterial activity assayed by zone of inhibition and test tube tests against pathogenic Vibrio sp. The results of the zone inhibitory test revealed that all the Ag/TEPA-Den-SiO 2 samples had an antibacterial effect against luminous Vibrio sp. Persian1. In addition, the tube test results showed 100% killing of bacteria in 2h contact period. Ag/ TEPA-Den-SiO 2 samples maintained their antibac- terial activity after 14-day immersion in seawater by slow release of silver ions. These results suggest that Ag/TEPA-Den-SiO 2 substrates could be effective antibacterial materials for dis- infection of seawater used to culture Penaeid shrimp larvae. Keywords: antibacterial activity, Silver nanopar- ticles, Vibrio sp., Shrimp Introduction Aquaculture is one of the main food providers in the world and shrimp culture is known as an important aquaculture activity in numerous areas. The shrimp aquaculture industry has been damaged especially by viral and bacterial diseases (Moriarty 1999). Vib- riosis is the most predominant bacterial disease that causes mass mortalities of the cultured shrimp worldwide (Lavilla-Pitogo, Leano & Paner 1998). Vibrio species often cause mortality in both hatch- eries and grow-out ponds (Mohney, Lightner & Bell 1994). Early mortality syndrome (EMS) or more descriptively called acute hepatopancreatic necrosis syndrome (AHPNS) has emerged as a new disease of shrimp since 2009. This disease has caused significant mortalities of Pacific White shrimp Litopenaeus vannamei and black tiger shrimp Penaeus monodon in Southeast Asian shrimp farms. EMS/ AHPNS pathogen has been identified as a member of the vibrio harveyi clade, most closely related to V. parahemolyticus (Tran, Nunan, Redman, Mohney, Pantoja, Fitzsimmons & Lightner 2013). Chemical treatment of vibriosis among shrimp larvae is quite limited because of the ineffectiveness of existing drugs, resistance among vibrio species, high toxicity, human health hazards and high price of drugs (Krishnani, Kathiravan, Shakil, Singh, Brahmane, Meena, Sarkar, Choudhary, Singh & Kumar 2015). Therefore, there is a need to investigate novel con- trol strategies for shrimp diseases. © 2016 John Wiley & Sons Ltd 2120 Aquaculture Research, 2017, 48, 2120–2132 doi: 10.1111/are.13048