XXX-X-XXXX-XXXX-X/XX/$XX.00 ©20XX IEEE Foundation Research Support of the State of São Paulo (FAPESP) and CAPES. Silver and Silver-Iron Nanoparticles Synthesized by Photoreduction for Applications in Cancer Therapy Karina de Oliveira Gonçalves Departamento de Física Universidade Federal de São Paulo Diadema, Brazil kgoncalves@unifesp.br Lilia Coronato Courrol Departamento de Física Universidade Federal de São Paulo Diadema, Brazil lccourrol@gmail.com Fúlvio Corazza Biotechnology Center Institute of Energy and Nuclear Research São Paulo, Brazil fcfulviocorazza@gmail.com Daniel Perez Vieira Biotechnology Center Institute of Energy and Nuclear Research São Paulo, Brazil dpvieira@ipen.br Abstract— Metal nanoparticles have been extensively studied for various purposes including therapeutic applications for cancer. In this study, nanoparticles of silver and silver-iron with aminolevulinic acid (ALA) were synthesized using (ALA:AgNPs and ALA:AgFeNPs) the photoreduction method with a 300 W xenon lamp, characterized by UV/vis absorption, zeta potential, x-rays diffraction, FTIR and transmission electron microscopy. The sizes obtained were ~ 23 nm for silver and ~ 12 nm for iron. Cytotoxicity assays were performed on breast tumor cells (MCF-7) and prostate cancer cells (LNCaP). The results obtained showed that it was possible to synthesize silver and silver-iron nanoparticles by the photoreduction method, and to functionalize their surfaces with ALA, which was delivered to the cells and converted to protoporphyrin IX (PpIX). Keywords— silver nanoparticles, iron nanoparticles, photoreduction, cancer Introduction Silver nanoparticles (AgNPs) attract significant interest because of their applicability in various areas [1]. The antimicrobial properties of AgNPs demonstrate efficiency against more than 650 pathogenic organisms, making these nanostructures applicable to products in the medical-hospital area (tissues and implants), shoes and sneakers, food storage containers, washing machines and air conditioners [2,3]. In biological systems, silver nanoparticles can cause the production of reactive oxygen species, changes in the cell cycle, damage to the genetic material, inflammatory processes and cell death [4]. In a study published by Asharani et al (2009), the toxicity of silver nanoparticles was tested in human lung fibroblasts and human glioblastoma cells [5]. The results showed the presence of AgNPs in the nucleus and in the mitochondria, which indicated a rupture of the mitochondrial respiratory chain originating reactive oxygen species (ROS) and blockage of ATP synthesis causing DNA damage. Generation of ROS is also known to induce apoptosis/cell death in various cell culture models [6]. Silver nanoparticles have applications in cancer treatment and are drug transporters that can deliver therapeutic agents. [7]. Aminolevulinic acid (ALA) is the first metabolite in the heme biosynthesis pathway. Porphyrins are biosynthesized from aminolevulinic acid (ALA). Moan et. al [8] showed enhanced ALA-mediated protoporphyrin IX (PpIX) accumulation in tumor cells and effective cell destruction after light illumination. The objective of this study was to synthesize metallic nanoparticles (silver and iron) by the photoreduction method, and at the same time functionalize the surfaces with aminolevulinic acid (ALA), improving the delivery of the drug, and increasing the cytotoxic effects on tumor cells [9]. I. MATERIALS AND METHODS A. Silver and silver-iron nanoparticles with 5-ALA To prepare ALA:AgNPs, 45 mg de AgNO3 were mixed with 13.5 mg de ALA and 30 mg of polyethylene glycol (PEG) in 30 mL of distilled water at 20 o C. The process was accompanied by vigorous stirring for 5 minutes, and 10 mL of the resulting solution was exposed to a 300 W xenon lamp for 1 minute. After irradiation pH solution was adjusted to ~ 7.0. To prepare ALA:AgFeNPs, 45 mg of iron powderwere diluted in 30 mL of distilled water and the pH solution was adjusted to 12. After that, 45 mg of AgNO3, 13.5 mg of ALA and 30 mg of PEG were added in solution, homogenized for 5 minutes and then exposed to a 300 W xenon lamp for 1 minute. After irradiation, the pH solution was adjusted to ~ 7. B. Characterization The UV-vis absorption spectra were measured by a Shimatzu spectrophotometer, using 1-cm quartz cells. The shape and sizes of ALA:AgNPs and ALA:AgFeNPs were obtained from transmission electron microscope (TEM) a Jeol (Zeiss, Germany). The effective surface charges on the ALA:AgNPs and ALA:AgFeNPs were measured using zeta potential (Malvern Instruments Zetasizer, Worcestershire, UK). The structural identification of the ALA:AgFeNPs sample was performed using the X-ray diffraction analysis (XRD) measurement using a Bruker D8 Advance 3kW diffractometer (Cu radiation tube, 250 mm goniometer, 40 kV, 30 mA) at Multiuser Center of the Nuclear Fuel (IPEN/CNEN-SP). The technique was performed for silver- iron nanoparticles. The material was separated using a