| Abstract
| - We report the fabrication and characterization of antifouling polymer-coated magnetic nanoparticles as nanoprobes for magnetic resonance (MR) contrast agents. Magnetite superparamagnetic ironoxide nanoparticles (SPION) were coated with the protein- or cell-resistant polymer, poly(TMSMA-r-PEGMA),to generate stable, protein-resistant MR probes. Coated magnetic nanoparticles synthesized using twodifferent preparation methods (in situ and stepwise, respectively) were both well dispersed in PBS bufferat a variety of pH conditions (pH 1−10). In addition, dynamic light scattering data revealed that their sizeswere not altered even after 24 h of incubation in 10% serum containing cell culture medium, indicative ofa lack of protein adsorption on their surfaces. When the antibiofouling polymer-coated SPION were incubatedwith macrophage cells, uptake was significantly lower in comparison to that of the popular contrast agent,Feridex I.V., suggesting that the polymer-coated SPION can be long-circulated in plasma by escapingfrom uptake by the reticular endothelial system (RES) such as macrophages. Indeed, when the coatedSPION were administered to tumor xenograft mice by intravenous injection, the tumor could be detectedin T2-weighted MR images within 1 h as a result of the accumulation of the nanomagnets within the tumorsite. Although the poly(TMSMA-r-PEGMA)-coated SPION do not have any targeting ligands on their surface,they are potentially useful for cancer diagnosis in vivo.
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