Cellular interaction with Si- and Iron-based nanoparticles for bio-imaging. A study of biocompatibility. I. Rivolta 1 , R. D’Amato 2 , R. Alexandrescu 3 , M. Falconieri 2 , I Morjan 3 , M. Chanana 5 , , V. Bouzas 4 , R. Costo 6 , F. Fabbri 2 , C. Fleacé 3 , M. A. Garcia 4 , P. Gasco 7 , W. Gonzalez 8 , , M. P. Morales 6 , Y. Nie 5 , G. Riccio 7 , C. Robic 8 , G. Sancini 1 , , N. Vivenza 7 , H. Xu 5 , V. Bello 9 , V. Maurice 10 , O. Sublemontier 10 , G. Mattei 9 , N. Herlin 10 , D. Wang 5 , J. M. Idee 8 , E. Trave 9 M. Port 8 , S. Veintemillas-Verdaguer 6 , E. Borsella 2 , G. Miserocchi 1 1 DIMS, Univ. of Milano-Bicocca, , Italy; 2 ENEA, Dept. FIM, Rome, Italy; 3 Natl Inst Lasers Plasma & Radiat Phys, Romania; 4 Univ Complutense Madrid, Dpto Fis Mat, Spain; 5 Max Planck Institute of Colloids and Interfaces, Dept. of Interfaces, Germany; 6 ICMM-CSIC C/Cantoblanco, Spain; 7 Nanovector S.r.l., Italy; 8 Guerbet Res, France; 9 University of Padova, Dept. of Physics, Italy; 10 Laboratoire Francis Perrin, SPAM, DSM, CEA Saclay, France. Abstract The overall objective of BONSAI project (FP6, EC) is the development of ultrasensitive bio-imaging techniques based on novel multifunctional nanoparticles (NPs) with tailored optical and magnetic properties for visualizing complex cellular structures (in tissues and organs), receptors, tumour cells and masses. An important aspect to take into consideration involves the cellular responses to the impact of exogenous structures represented by NPs themselves. As a preliminary sign of reaction, we start to investigate the basic cytotoxicity. 1. INTRODUCTION The field of bio-medical applications of NPs is still in its infancy as a consequence of the difficulties encountered in getting stable particles, easy dispersible in aqueous biological media and bio-compatible. True innovation in term of nanoparticles production rests on the capability to combine the preparation of “ad-hoc” NPs, having different properties and functions, with the development of advanced bio-imaging techniques. The expected improvements of labelling cells and cellular structures with tailored NPs are sensitivity, speed and specificity in the visualization of biological systems. The goal of the BONSAI project is the development of stable solutions containing non-cytotoxic, Si- and iron-based NPs surface functionalized to improve and tune their optical properties and to increase their selectivity for bio-imaging of specific biological targets. These NPs will be most useful for the development of optical bio-imaging techniques aiming at: cell labelling for detection and tracking for lineage studies; optical imaging of in-vitro and in-vivo tumour cells for early cancer diagnostics. Silicon is not a good light emitter, while nanostructured Si can emit photons in the visible- near IR range with a reasonable efficiency (1). It follows that silicon nanoparticles (Si-NPs) have the potential to overcome the inherent limitations in the biomedical use of Quantum Dots (QDs) because silicon is inert, non-toxic, abundant, economical and can be surface functionalized to allow stabilization and bioconjugation steps (2,3). In this project we investigate weather these NPs will be biocompatible as compared to largely investigated, toxic CdSe QDs that require permanent biocompatible coatings. Imaging can also be generated by exposure of cells or tissues to magnetic fields and by measuring dephasing times of water protons as in MRI (Magnetic Resonance Imaging). Actually, magnetic NPs are produced by complex multistep chemical procedures that unavoidably give rise to final particle sizes greater than 50 nm. The NP synthesis procedure proposed in this Project leads to the production of Fe-based magnetic NPs with size lower than 20 nm. The success in reaching this objective will lead to the production of new contrast agents for MRI with superior or compatible performances. In this project we will also propose to use Solid Lipid Nanoparticles (SLNs) as a carrier of either Si- or iron-based NPs. SLNs offer the advantage of being biocompatibile and stable. 2. MATERIAL AND METHODS NPs preparation: The NPs synthesys procedures employed in the BONSAI project is a one step process based on CO 2 laser induced pyrolysis of suitable gas-phase precursor. Silicon nanopowders were produced by laser pyrolysis of silane. The as-prepared particles (diameter averaged 4 nm) were dispersed in ethanol at a typical concentration in the range of 8 g/l and were diluted in cell medium (1% FBS) before test. Superparamagnetic iron oxide nanoparticles were produced by the fast laser heating of iron pentacarbonyl in an oxidant environment. Gases of high thermal conductivity (i.e. He, N 2 ) were used in order to favor the cooling of the nanoparticles as well as the decrease of the iron pentacarbonyl temperature during the synthesis. The result of this combined approach was the production of iron oxide nanoparticles with an almost spherical shape, TEM mean diameter of 3.0±1.2 nm and cell 716 978-981-08-3694-8 (RPS) c 2009 IEEE NANO Organizers