Synthesis and characterization of heat-stabilized albumin magnetic microspheres

Human serum albumin magnetic microspheres containing 30% iron oxide particl es were synthesized by a heat-stabilization process. The average diameter, the size distribution and the morphology were characterized by scanning ele ctron microscopy, atomic force microscopy and transmission electron microsc opy. The distribution of the iron oxide nanoparticles within the microspher es was confirmed by the contrast obtained in the morphology by backscattere d electron imaging in scanning electron microscopy. Energy-dispersive X-ray spectroscopy showed the presence of iron in the microspheres. The cabbage like surface structure in some of the microspheres obtained in scanning ele ctron microscopy can be better understood by atomic force microscopy. This peculiar surface structure in the microsphere may be due to the cross-linki ng in the protein molecule by heat. The amount of iron oxide in the microsp here was analyzed by atomic absorption spectroscopy. The magnetic propertie s of the particles were measured in a superconducting quantum interference device magnetometer.