Synthesis and Characterization of ThiolCapped FePt Nanomagnetic Porous Particles

Technologies based on magnetic separation have recently been widely explored?-51 This can be described as a two-step process, involving: 1) the tagging or labeling of a desired biological/chemical entity on colloidal magnetic particles for the recognition of complementary species in solution, and 2) the separation of the resulting solid entities via a fluid-based magnetic separation followed by regeneration of the species from the particle.'61 This technique is now widely adopted in protein purification, immunoassays?' preprocessing in polymerase chain reactions,'81 and pre-concentration of biological entitiesP Recently, applications of magnetic separation to catalysis and biocatalysis in order to regenerate expensive catalyst species''' or enzymes" from reaction mixtures have been particularly studied. Concerning the use of magnetic nanoparticles in magnetic separation, two key problems require urgent attention. First, many magnetic materials with a strong magnetization (such as magnetic alloys) are chemically susceptible to attack (e.g., oxidation, hydrolysis) during the separation and thus deemed unsuitable for this purpose. Referring to its particular application in (bio)catalysis, an undesirable catalytic reaction could also be introduced if the reactive surface of the magnetic core is exposed to substrate molecules. Secondly, there are limited numbers of surface sites on the magnetic particle for carrying biological/chemical species and no physical storage of the species in a significant quantity can be made possible. The availability of reported chemical methods to modify surface properties and to add a coating to nanomagnetic colloidal particles in solution is limited since the particles tend to agglomerate very easily during subsequent treatment(s).