water and 0 1 g of sodium dodecyl sulfate are added to an erlenmeyer flask under stirring and then is left soaking for 15 hours at room temperature the poly styrene glycidyl methacrylate submicron particles are prepared by copolymerizing glycidyl methacrylate and styrene the molar ratio is 5 100 in the presence of potassium persulfate as an initiator using the emulsifier free emulsion polymerization subsequently 5 ml of 24 mg ml fe 3 o 4 magnetic nanoparticle aqueous solution is added to the ps gma solution prepared above at 30 u00b0 c with stirring at 140 rpm for 24 hours in order to allow the magnetic nanoparticles to enter the interior of the ps gma particles afterwards the ps gma submicron particles are separated from the solution by centrifuging sequentially washed three times with methanol and three times with deionized water and dried by vacuum drying at room temperature for 1 2 days to obtain the magnetic polymer microbeads fig8 shows the scanning electron micrograph of the magnetic polymer microbeads according to this embodiment the average particle diameter of the magnetic polymer microbeads is about 0 38 u03bcm fig9 shows the magnetization curve of the magnetic polymer microbeads and the saturation magnetization are found to be up to 16 emu g the magnetic polymer microbeads prepared above have the surface epoxy groups which can bond to various biomolecules the surface epoxy groups can be modified by conventional chemical reactions so that the magnetic polymer microbeads can have different functional groups such as carboxyl groups aldehyde groups amino groups hydroxyl groups or the like following the same procedure as example 9 four separate sets of ps gma solutions are prepared each set of ps gma solutions is prepared as following 0 5.