10.22376/ijpbs.2019.10.1.p1-12 Volume 5 Issue 3 2014 (July- September) Iron oxide nanoparticles were synthesized and coated with silica by conventional co-precipitation method. Silica coated iron oxide nanoparticles were surface functionalized with chitosan. Silica coating and chitosan functionalization were confirmed by FTIR and TG-DTA analysis. XRD pattern revealed that the pure phase of Fe lessThan sub greaterThan 3 lessThan /sub greaterThan O lessThan sub greaterThan 4 lessThan /sub greaterThan was retained even after coating. Particles of average size 12 nm were obtained as revealed in TEM images. The chitosan functionalized Fe lessThan sub greaterThan 3 lessThan /sub greaterThan O lessThan sub greaterThan 4 lessThan /sub greaterThan @Silica superparamagnetic nanoparticles show a saturation magnetization as high as 56emu/g and enriched rapidly under external magnetic field. The results point out the prospective of these nanoparticles to be used as adsorbent and desorbent of negatively charged DNA. The nanoparticles were successfully exploited for purification of DNA from lessThan i greaterThan Escherichia coli lessThan /i greaterThan bacterial culture. The A lessThan sub greaterThan 260 lessThan /sub greaterThan /A lessThan sub greaterThan 280 lessThan /sub greaterThan value of eluted DNA was close to 1.8, indicating that the isolated DNA is relatively pure and without RNA and protein contamination. The whole process relied on an instrument free "green chemistry" approach and eliminates the need of toxic chemicals. A. P. TIWARI, S. J.GHOSH AND S.H PAWAR DNA isolation, Magnetic separation, Chitosan, superparamagnetic nanoparticles, Fe3O4@Silica. 533-542