Abstract—Nanosized materials are attracting a great deal in biological and pharmaceutical applications. Especially, metal oxide nanoparticles are known to possess antibacterial properties. TiO 2 nanoparticles, have become a new generation of advanced materials due to their optical, dielectric, and photo-catalytic characteristics from size quantization. These properties have been applied in removing bacteria and harmful organic materials from water and air. In this work, we investigated antimicrobial activity of synthesized TiO 2 nanoparticles by ultrasound method. The TiO 2 nanoparticles were characterized by X-ray diffraction, nano sizer and atomic force microscopy analyses. The antibacterial effect of these obtained nanoparticles was examined on E. coli (ATCC 8739), Staph.aureus (ATCC 6538), P.aeruginosa (ATCC 9027), C.albicans (ATCC 36232) and B.subtilis (ATCC 6633). The synthesized TiO 2 nanoparticles were found to be effective against these bacterias. Based on this study, we may conclude that the synthesized by ultrasound method TiO 2 nanoparticles can be a good inorganic antimicrobial agents. Keywords— Antimicrobial activity, TiO 2 Nanoparticles, Minimum inhibitory concentration, Escherichia coli, Staphylococcus aureus. I. INTRODUCTION ANO as a word means one-billionth of a physical quantity. One nanometer is a unit of length equal to one billionth of a meter. Nanoscale materials have very different new properties which differ from materials in molecular form. Nanomaterials have a much greater surface area to volume ratio than their conventional forms. The large surface area affects the interaction of the elements and nanoparticles. That is quite different than the larger size of the electrical, mechanical, optical and magnetic characteristics of atomic and molecular sizes (1-100 nm), functional materials, devices, systems subject to the production of the branch of science is called nanotechnology [1]. Nanotechnology is emerging as a rapidly growing field with its application in Science and Technology for the purpose of manufacturing new materials at the nanoscale level [2]. Sabriye Piskin, Yildiz Technical University Chemical Engineering Department, Davutpasa Campus, 34210 Esenler, Istanbul, Turkey (phone: +90 212 383 4729; fax:+90 212 383 4625; e-mail: piskin@yildiz.edu.tr). Arzu Palantöken, Yildiz Technical University Chemical Engineering Department, Davutpasa Campus, 34210 Esenler, Istanbul, Turkey (e-mail: apalantoken@gmail.com). Muge Sarı Yılmaz, Yildiz Technical University Chemical Engineering Department, Davutpasa Campus, 34210 Esenler, Istanbul, Turkey (e-mail: mugesari@yildiz.edu.tr). It can prove to be a boon for human health care, because nanoscience and nanotechnologies have a huge potential to bring benefits in areas as diverse as drug development, water decontamination, information and communication technologies, and the production of stronger, lighter materials [3]. Nanomaterials may also used for special medical purposes such as to produce novel drug delivery systems, to enhance the performance of medical devices, or to produce diagnostic imaging materials [4]. An antimicrobial refers to a substance that kills or inhibits the growth of microorganisms [5]. Antimicrobial agents are highly relevant for a host of industrial applications in environmental, food, synthetic textiles, packaging, health care, and medical care products. Metal oxide nanoparticles (NPs) are known to possess strong antimicrobial properties [6]. In addition to industrial uses, such as catalysts, these are also used in products familiar to ordinary consumers such as sunscreens, cosmetics, pharmaceutical products, and fuel additives [7]. Titanium dioxide (TiO 2 ) is a photo catalyst and widely utilized as a self-cleaning and self disinfecting material for surface coating in many applications. It has a more helpful role in our environmental purification due to its nontoxicity, photo induced super-hydrophobicity and antifogging effect [8]. They are used frequently in cosmetics, pharmaceutical, paint and paper industry. However, the small particle size of nanoparticles may have different chemical, magnetic optical and structural features, so they may have more differential toxicity profiles than normal-sized TiO 2 . II. EXPERIMENTAL A. Materials and methods All reagents used in the synthesis of TiO 2 and antibacterial studies were analytical grade and employed without any further treatments. Distilled water was used for all synthesis and antimicrobial activity processes. Esherichia coli (ATCC 8739), Stapyloccus aureus (ATCC 6538), Pseudomonas aeruginosa (ATCC 9027), Candida albicans (ATCC 36232) and Bacillus subtilis (ATCC 6633) were obtained from American Type Culture Collection. All the media and chemicals were purchased from Oxoid Microbiology Products and Difco Laboratories. Antimicrobial Activity of Synthesized TiO 2 Nanoparticles Sabriye Pişkin, Arzu Palantöken, and Müge Sari Yılmaz N International Conference on Emerging Trends in Engineering and Technology (ICETET'2013) Dec. 7-8, 2013 Patong Beach, Phuket (Thailand) http://dx.doi.org/10.15242/IIE.E1213004 91