Romanian Reports in Physics, Vol. 66, No. 3, P. 778–787, 2014 USING AFM TOPOGRAPHY MEASUREMENTS IN NANOPARTICLE SIZING D. CHICEA 1,2 1 “Lucian Blaga” University of Sibiu, Environmental Sciences Department, Dr. Ion Ratiu Str. 7-9, Sibiu, ηη0012, Romania, dan.chicea@ulbsibiu.ro 2 Pediatric Respiratory Medicine Research Center (CCMRP), Str. Pompeiu Onofreiu Nr. 2– 4, Sibiu Received July 19, 2013 Abstract. Two simple recipes for preparing Fe 3 O 4 nanoparticles are briefly presented. The nanoparticles were characterized using Dynamic Light Scattering and Atomic Force Microscopy. The results of the DLS procedure are presented in detail and discussed in connection with the AFM results, highlighting the differences between the size distribution in connection with the preparation parameters. Key words: dynamic light scattering, atomic force microscopy, Fe 3 O 4 nanoparticles. 1. INTRODUCTION Nanoparticle structured materials have been used to investigate living cells or to deliver certain substances or drugs to them. This is possible as the nanoparticle dimension is smaller than the cell organelles. Certain applications of nanostructured materials in biology and medicine have been developed and are presented in review papers, [1] being just one of them. In recent years warnings on the potential danger of the nanoparticles in environment were issued [2] though. Consequently different techniques of detection and monitoring the nanoparticle concentration are presented in the literature [2]. Nanoparticle penetration through the cell membrane strongly depends of the nanoparticles physico-chemical properties as shape, size, surface charge, surface chemistry [3], therefore it is of interest to characterize the nanoparticles size and size distribution prior of using them in biomedical applications. Fe 3 O 4 nanoparticles are of special interest for biomedical applications because they are not toxic [4] and they can be metabolized by living organisms [4]. They present a major inconvenient though, as they aggregate very fast in diluted aqueous suspension [η], as the body fluids are. The former nanofluid quickly exhibits micron sized particles in suspension.