PEGylation of SPIONs by polycondensation reactions: a new strategy to improve colloidal stability in biological media

  • Wesley Renato Viali
  • Eloiza da Silva Nunes
  • Caio Carvalho dos Santos
  • Sebastião William da Silva
  • Fermin Herrera Aragón
  • José Antonio Huamaní Coaquira
  • Paulo César Morais
  • Miguel JafelicciJr.
Research Paper


In this study, we report on a new route of PEGylation of superparamagnetic iron oxide nanoparticles (SPIONs) by polycondensation reaction with carboxylate groups. Structural and magnetic characterizations were performed by X-ray diffractometry (XRD), transmission electron microscopy (TEM), thermogravimetric analysis (TGA), and vibrating sample magnetometry (VSM). The XRD confirmed the spinel structure with a crystallite average diameter in the range of 3.5–4.1 nm in good agreement with the average diameter obtained by TEM (4.60–4.97 nm). The TGA data indicate the presence of PEG attached onto the SPIONs’ surface. The SPIONs were superparamagnetic at room temperature with saturation magnetization (M S) from 36.7 to 54.1 emu/g. The colloidal stability of citrate- and PEG-coated SPIONs was evaluated by means of dynamic light scattering measurements as a function of pH, ionic strength, and nature of dispersion media (phosphate buffer and cell culture media). Our findings demonstrated that the PEG polymer chain length plays a key role in the coagulation behavior of the Mag-PEG suspensions. The excellent colloidal stability under the extreme conditions we evaluated, such as high ionic strength, pH near the isoelectric point, and cell culture media, revealed that suspensions comprising PEG-coated SPION, with PEG of molecular weight 600 and above, present steric stabilization attributed to the polymer chains attached onto the surface of SPIONs.


SPIONs PEG Iron oxide Surface modification Magnetic fluid Colloidal stability 



This study was supported by the Brazilian agencies Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP 2010/20546-0), the Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq 476257/2010-7), the Empresa Brasileira de Pesquisa Agropecuária (EMBRAPA), and the Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES). The authors would like to thank LME/LNNano/CNPEM for technical support during electron microscopy investigation.

Supplementary material

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Supplementary material 1 (PDF 1407 kb)


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Copyright information

© Springer Science+Business Media Dordrecht 2013

Authors and Affiliations

  • Wesley Renato Viali
    • 1
  • Eloiza da Silva Nunes
    • 1
  • Caio Carvalho dos Santos
    • 1
  • Sebastião William da Silva
    • 2
  • Fermin Herrera Aragón
    • 2
  • José Antonio Huamaní Coaquira
    • 2
  • Paulo César Morais
    • 2
    • 3
  • Miguel JafelicciJr.
    • 1
  1. 1.Laboratório de Materiais Magnéticos e Coloides, Departamento de Físico-química, Instituto de QuímicaUniversidade Estadual PaulistaAraraquaraBrazil
  2. 2.Instituto de Física, Núcleo de Física AplicadaUniversidade de BrasíliaBrasíliaBrazil
  3. 3.Department of Control Science and EngineeringHuazhong University of Science and TechnologyWuhanChina

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