MAGNETIC FLUIDS CONSISTING OF MAGNETITE NANOPARTICLES ARE THE SUBJECT OF MANY RECENT STUDIES, ESPECIALLY IN BIOLOGICAL APPLICATIONS SUCH AS CELL SEPARATION AND SORTING, MAGNETIC DRUG DELIVERY AND MAGNETIC RESONANCE IMAGING [1, 2]. MAGNETITE FE3O4 NPS ARE THE MOST COMMONLY USED MAGNETIC MATERIAL DUE TO ITS HIGH SATURATION MAGNETIZATION MS (90EMU/G). IN THIS PAPER FIRST MAGNETIC NANOPARTICLES (MNPS) OF ABOUT 10NM DIAMETERWERESYNTHESIZED BY METHOD CO-PRECEPITATION IRON SALTS (II), (III) IN AN AMMONIA SOLUTION, THEN CITRIC ACID WAS USED TO STABILIZE THE MAGNETIC PARTICLES SUSPENSION, IT WAS ANCHORED ON THE SURFACE OF FRESHLY PREPARED MNPS BY DIRECT ADDITION METHOD. THE MICROSTRUCTURE AND MORPHOLOGY OF THE NANOPARTICLES WERE CHARACTERIZED BY XRD, SEM AND TEM, AND THE INTRACTION BETWEEN CITRIC ACID AND MNPS WAS CHARACTERIZED FT-IR. IN THE NEXT STEP USED OF SYNTHESIZED NANOPARTICLES IN PREPARATION OF polymeric BIO-films WITH VARITY CONCENTRATINS.