PEGylation of SPIONs by polycondensation reactions: a new strategy to improve colloidal stability in biological media
- 369 Downloads
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.
KeywordsSPIONs 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.
- Barrera C, Herrera AP, Bezares N, Fachini E, Olayo-Valles R, Hinestroza JP, Rinaldi C (2012) Effect of poly(ethylene oxide)-silane graft molecular weight on the colloidal properties of iron oxide nanoparticles for biomedical applications. J Colloid Interf Sci 377:40–50. doi: 10.1016/j.jcis.2012.03.050 CrossRefGoogle Scholar
- Cabuil V, Massart R, Bacri JC, Perzynski R, Salin D (1987) Ionic ferrofluids—toward fractional distillation. J Chem Res-S 5:130–131Google Scholar
- Cornell RM, Schwertmann U (2004) Surface chemistry and colloidal stability. In: The iron oxides. Wiley Weinheim, pp 221–252Google Scholar
- Cullity BD (1978) Elements of X-ray diffraction 2nd edn. Addison-Wesley, ReadingGoogle Scholar
- Cullity BD, Graham CD (2009) Introduction to magnetic materials. IEEE Press, PiscatawayGoogle Scholar
- Hiemenz P, Rajagopalan R (1997) Principles of colloid and surface chemistry. Marcell Dekker, New YorkGoogle Scholar
- Hunter RJ (1981) Zeta potential in colloid science principles and applications. Academic Press, LondonGoogle Scholar
- Nakamoto K (1970) Infrared spectra of inorganic and coordination compounds, 4th edn. Wiley, New YorkGoogle Scholar
- Roca AG, Costo R, Rebolledo AF, Veintemillas-Verdaguer S, Tartaj P, Gonzalez-Carreno T, Morales MP, Serna CJ (2009) Progress in the preparation of magnetic nanoparticles for applications in biomedicine. J Phys D Appl Phys 42 (22). doi: 10.1088/0022-3727/42/22/224002
- Unsoy G, Yalcin S, Khodadust R, Gunduz G, Gunduz U (2012) Synthesis optimization and characterization of chitosan-coated iron oxide nanoparticles produced for biomedical applications. J Nanopart Res 14 (11). doi: 10.1007/S11051-012-0964-8