Synthesis Of Magnetic Iron Oxide Nanoparticles And The Interaction Between Magnetic Iron Oxide Nanoparticles With Biomacromolecules And Cells

Magnetic iron oxide nanoparticles (MNPs) have shown great prospects in a wide variety of biological and biomedical applications such as bioseparation, immunoassay, tumor hyperthermia, and MRI owing to their unique magnetic properties and nano-characters. However, little is known about its potential adverse effects in vivo due to prolonged exposure in biological systems, which is a bottleneck to the development of MNPs on nanobiology and nanomedicine. Since we studies on the interactions between MNPs with biomacromolecule and cells in order to investigate biological effect of MNPs.The interaction of MNPs with bovine serum albumin (BSA) was investigated by fluorescence (FL), ultraviolet visible absorption (UV-vis), Raman and circular dichroism (CD) spectroscopy. Results indicated that MNPs quench BSA FL mainly by a static quenching mechanism. The FL quenching constants, thermodynamic parameters, the association constant and the number of binding sites were calculated, respectively. Analysis results suggested that the interaction was spontaneous and the electrostatic interactions played key roles in the reaction process. In addition, the Raman and CD spectra proved secondary structure alteration of BSA in the presence of MNPs.MNPs were synthesized by microwave-assisted coprecipitation. The effects of MNPs on the calf thymus DNA (ct DNA) were evaluated by UV-vis spectra, Raman spectra and Agarose gel electrophoresis (AGE), respectively. UV-vis spectra revealed the hyperchromic effect on ct DNA due to the exposure of basic group that induced by MNPs. Raman spectra indicated the basic group, ribodesose and backbone were disturbed in the presence of MNPs. However, AGE confirmed that DNA melting or DNA strand break haven’t occurred under the influence of MNPs.The MNPs and carbon decorated magnetic iron oxide nanoparticles (C-MNPs) were synthesised by thermal decomposition and hydrothermal method, respectively. It was found that the synthesized MNPs were spherical in shape with an average size of 14 nm, low aggregation and good magnetic responsivity. Meanwhile, the majorty of MNPs were carbonized to carbon decorated MNPs,20 nm in size; the minorities were self-assembled to a flowerlike nanostructure,5μm in diameter approximately. The cytotoxicity of MNPs and C-MNPs towards HeLa cells was investigated by MTT analysis. The MNPs and C-MNPs revealed significant cell growth stimulating activities in light concentration. Supposedly the trace iron released from MNPs and C-MNPs could be taken up by HeLa cells as an iron source, benefiting their growth. In addition, it was observed that the C-MNPs could effectively stimulate the growth of HeLa cells in light concentration while dropped gradually in high concentration because of the physiological environment for HeLa cells growth were disturbed under conditions of C-MNPs overload.