Synthesis and characterization of amino functional poly(acrylamide) coated Fe 3 O 4 nanoparticles and investigation of their potential usage in DNA isolation

This study focuses on the synthesize of magnetic nanoparticles (MNPs) that can be used practically in the separation and purification processes of DNA. For this purpose, firstly, bilayer oleic acid coated Fe 3 O 4 (magnetite:M) nanoparticles with high water dispersibility and dispersion stability were synthesized. Subsequently, various amounts of acrylamide and crosslinker N, N-methylenebisacrylamide (NMBA) were added to the aqueous solution containing 4% by weight of magnetic particles, and the surface of the magnetic particles was coated with a cross-linked polyacrylamide (pAAm) by using reverse emulsion polymerization technique. Finally, these pAAm coated particles were modified by transamidation reaction with ethylene diamine yielding aminofunctional core–shell structure MNPs. The synthesized MNPs were characterized by various tests and techniques such as amine value (AV), FTIR, XRD, DLS, and TGA. The results showed that lowest particle size, narrow size distribution, and highest AV without any significant loss of magnetic properties can be obtained after EDA modification when acrylamide mole amount is fixed to 10 –2 mol in the polymerization reaction (particle size = 180 nm; AV:19.53 mmol/g). Finally, the DNA isolation studies showed that 4.5 μg/mg DNA adsorption capacity can be achieved at pH4 in 30 min; while 80% of the adsorbed DNA can be desorbed at pH 10 in 10 min. The obtained results indicated the effectiveness and convenience of the synthesized MNPs in biotechnology and DNA separation processes.