Dispersion of nanoparticles in media of biological interest
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Dispersion of nanoparticles in media of biological interest Marie Carriere1, Axelle Casanova2 and N. Herlin Boime2 1 Lésion des Acides Nucléiques (UMR E3 CEA-UJF) 17 rue des Martyrs, 38054 Grenoble Cedex 09, France 2 Laboratoire Francis Perrin/ Service des Photons, Atomes et Molécules (CEA CNRS URA 2453), IRAMIS, Bat 522, CEA Saclay, 91191 Gif/Yvette Cedex, France ABSTRACT Nanoparticles (NP) are introduced in a growing number of commercial products, including food and beverage, daily use hygiene products such as toothpaste, or orallyadministered drugs. To study the possible toxicity of these nanoparticles, a model system is the in vitro response of eukaryotic cells to the presence of NP. However, to understand the observed effects, it is clear that good physical and chemical characterization of NP, and in particular of their dispersion are needed. Indeed, the expected effects should be different if the study is dealing with agglomerates or isolated nanoparticles. For fundamental understanding, it appears important to work with nanoparticles as well dispersed as possible while being in relevant biological condition, i.e. cellular culture cell. In this context, we have studied the dispersion of a very common industrial titania NP (Degussa P25 produced in ton quantities). When dispersed in water, the suspensions of NP appear stable for weeks.. When transferred in the cell culture medium (DMEM) or if directly dispersed in DMEM, strong evolution of size is seen as well as sedimentation. To address this problem, we have compared different ways, coming from materials science, of dispersing NP in water with the idea to break in a preliminary step some of the necks between nanoparticles. The effect of dry ball milling, liquid ball milling, size of the balls and Ultrasonic dispersion will be compared. The best results were obtained from high power ultrasonic dispersion. To avoid direct aggregation, when going to DMEM, a "surfactant" relevant with biological studies (Foetal Bovine Serum (FBS)) was added in the suspension in order to coat the nanoparticles prior to transfer in DMEM (or other cell media). The result obtained with various surfactants and cell media will be presented. It must be noted that our best results were obtained in the FBS + DMEM medium. INTRODUCTION Due to its properties of absorption of solar light in the UV range, titania is useful for a wide range of applications, including photoabsorbtion, photocatalysis or photovoltaic. It is industrially produced in large quantities at the nanometric scale and concerns about potential exposure of workers and population to nanoparticles (NPs) have emerged. Since about five years, more and more publications are dealing with the problem of toxicity of NPs. However, the results still show some variability which can be related to difficulties in the characterization of NPs as noted for example by Simon [1 and references therein]. The characterization of NPs (size of individual particles, cristallinity, surface state, shape,...) is now considered by most of the authors. H
