Carboxymethyl group activation of dextran cross-linked superparamagnetic iron oxide nanoparticles

Abstract

Synthesis of monodispersed magnetic nanoparticles with a highly stable and biocompatible were developed for biomedical applications in nanomedicine. In this work, the hydrophilic colloidal SPIONs was synthesized in the presence of dextran matrix by in-situ co-precipitation method. In this way, agglomeration of magnetic nanoparticles due to their intrinsic magnetic force was avoided. Moreover, a facial stepwise process was developed for carboxymethyl activated cross-linked superparamagnetic iron oxide nanoparticles (CM-CL-SPIONs). Image analysis results show that the average core particle diameter is around 5.7 nm once formed, and does not change significantly during both crosslinking and carboxymethylation process. The results of FT-IR spectra imply that the surface of SPIONs is successively modified with dextran molecules and their activation with carboxylic groups. The endothermic peak shift determined by DSC provides a supplementary evidence of the successful crosslinking and activation of CMD. The cytotoxicity of particles is examined by MTT assay, which is performed after incubation of human osteosarcoma cells with CL-SPIONs and CM-CL-SPIONs for 24 h in vitro. MG63 cells incubated with CL-SPIONs and CM-CL-SPIONs show similar cell viability and morphologies to that of controls, demonstrating that CM-CL-SPIONs do not have any significant adverse effect on cells. The introduction of a carboxylic functional group into the coating layer after crosslinking extends the feasibility of covalent attachment of bioactive molecules, such as proteins, peptides and oligonucleotides to SPIONs, while minimizing the potential problem of dissociation. The CM-CL-SPIONs can be used as versatile backbone nanocarriers in potential biomedical applications. Several characterization techniques are used to prove the step-by-step success of the synthetic procedure.