- 7 - - DEVELOPMENT OF BIOCOMPATIBLE COLLOIDAL FePt JASS Vol 52 No. 2, December 2011 DEVELOPMENT OF BIOCOMPATIBLE COLLOIDAL FePt NANOPARTICLES FOR NANOBIOMEDICAL APPLICATIONS USING A GREEN SYNTHETIC APPROACH P Deb 1 and E Kalita 2* 1 Department of Physics, Tezpur University (Central University), Tezpur 784028, Assam, India 2 Department of Molecular Biology and Biotechnology Tezpur University (Central University), Tezpur 784028, Assam, India E mail: ekalita@tezu.ernet.in Abstract FePt nanoparticles were synthesized using a green synthetic route, in a facile one- step process. The iron and platinum precursors were reduced in presence of the naturally available ascorbic acid to obtain the FePt nanoparticles. The synthesis parameters were modulated such that the FePt nanoparticles acquire biocompatible characteristics due to the ascorbic acid capping. The microstructural studies confirmed the formation of the ascorbic acid coating over the FePt nanoparticles. The role of the coating in enhancing the biocompatibility was demonstrated by the cytotoxicity assay on the coated and uncoated FePt nanoparticles. These nanoparticles have unique properties previously absent in the bulk materials. The magnetic and relaxivity studies on these FePt nanoparticles show promising attributes as precursors for T 2 contrast agents for magnetic imaging applications. Keywords: FePt, Ascorbic acid, biocompatibility, green synthesis. Introduction Nanoparticles (NP) has been able to arise considerable interest towards research applications over the last decade. The amalgamation of nanotechnology with modern medicine has brought to light previously unknown vistas and possibilities in the field of nanomedicine [1]. Nanomaterials have significantly enriched the diagnostic, therapeutic and bioengineering procedures and helped understand the complexities of biological systems at a molecular level [2,3]. Consequently, there is the potential of providing novel methods for the diagnosis and treatment of diseases which were previously difficult to target due to size restrictions. The increase in efforts to develop non-invasive methods for detection and diagnosis has led to rapid developments in the field of magnetic resonance imaging [4]. In most of the perceived applications, the best results are obtained with particles with sizes below a critical value, within a size range of 10–20 nm, depending on the type of materials used. At such dimensions the individual nanoparticles have a large constant magnetic moment with a rapid response to applied magnetic fields with negligible residual magnetism. These features make nanoparticles attractive prospects for application in diverse fields of magnetic imaging. FePt NPs offer an extensive range of magnetic properties and are much more stable than other well-known magnetic NPs used for magnetic imaging [5]. FePt NPs developed through chemical routes have many attractive features, such as their ease of synthesis, chemical stability and narrow size distribution [6]. In the current study, iron nitrate and platinum acetyl acetate precursors were reduced at room temperature in presence of ascorbic acid and/or NaBH 4 to obtain FePt NPs with narrow size distribution. The merit of the synthesis procedure lies in the fact that ascorbic acid acts as capping agent to convert hydrophobic FePt nanoparticles to hydrophilic biocompatible nanoparticles, with