Surfactant-free synthesis of Fe3O4@PANI and Fe3O4@PPy microspheres as adsorbents for isolation of PCR-ready DNA

Magnetic separation with composite microspheres presents an alternative strategy for applications in biomedical and bioengineering fields. However, the synthesis of core-shell structured magnetic composites universally assumes the surfactant-directing and/or silica-assisting polymerization approach to modify and stabilize the magnetic cores. In this paper, we report on the surfactant-free synthesis of well-defined core-shell structured Fe3O4@PANI and Fe3O4@PPy microspheres with high magnetization. The temperature dependence of magnetization of the samples was examined as a function of temperature between 3 and 300 K in an applied field of 500 Oe. It was found that the blocking temperature (T-B) values of the composite spheres are well above the room temperature. The small variation in magnetization as the temperature changes renders the composite spheres a suitable candidate when used at elevated temperatures. Also, the genomic DNA can be effectively isolated from Aspergillus niger (A. niger) cells with the composite microspheres, using a PEG-NaCl binding buffer and a phosphate eluting buffer. The magnetic isolation of genomic DNA with the composite microspheres was shown to be superior to the conventional phenol-chloroform extraction, which was confirmed by agarose gel eletrophoresis and polymerase chain reaction (PCR) diagnosis. The Fe3O4@PANI and Fe3O4@PPy microspheres presented here have great potential in enzyme immobilization, drug delivery, catalysis, and sensors.