Effect of poly(ethylene oxide)-silane graft molecular weight on the colloidal properties of iron oxide nanoparticles for biomedical applications

• Published in: Journal of colloid and interface science Vol. 377; no. 1; pp. 40 - 50
• Main Authors: Barrera, Carola, Herrera, Adriana P., Bezares, Nayla, Fachini, Estevão, Olayo-Valles, Roberto, Hinestroza, Juan P., Rinaldi, Carlos
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.07.2012; Elsevier
• Subjects: Biocompatible Materials - chemistry; Biological; buffers; cell culture; Chemistry; colloidal properties; Colloidal stability; Colloidal state and disperse state; Colloids; Colloids - chemistry; Culture; culture media; ethylene glycol; ethylene oxide; Exact sciences and technology; Ferric Compounds - chemistry; General and physical chemistry; Hydrodynamics; ionic strength; Iron oxide; iron oxides; Magnetic nanoparticles; Media; Molecular Weight; Nanoparticles; Nanoparticles - chemistry; Particle Size; Physical and chemical studies. Granulometry. Electrokinetic phenomena; Poly(ethylene glycol); polyethylene glycol; Polyethylene Glycols - chemistry; Silane; Silanes - chemistry; Stability; Surface Properties; van der Waals forces; X-ray photoelectron spectroscopy; Iron oxide; Colloidal stability; Silane; Magnetic nanoparticles; Poly(ethylene glycol); Water; Nanoparticle; X ray; Density; DLVO theory; Ethylene oxide polymer; Particle; Amine; pH; Photoelectron spectrometry; Molecular mass; Diameter; Surface charge; Stability; Transition element compounds; Hydrodynamics; Polymer; Thickness; Ionic strength; Colloidal suspension; Distribution; Van der Waals interaction; Models; Electrostatics
• ISSN: 0021-9797; 1095-7103
• DOI: 10.1016/j.jcis.2012.03.050

[Display omitted] ► Stability of PEG-silane grafted iron oxides evaluated in water and cell culture media. ► PEG-silane graft molecular weight had negligible effect on magnetic properties. ► Agreement observed between DLS hydrodynamic diameters and density distribution model. ► PEG molecular weight >1000g/mol needs to ensure colloidal stability. The size, charge, and stability of colloidal suspensions of magnetic nanoparticles with narrow size distribution and grafted with poly(ethylene glycol)-silane of different molecular weights were studied in water, biological buffers, and cell culture media. X-ray photoelectron spectroscopy provided information on the chemical nature of the nanoparticle surface, indicating the particle surfaces consisted of a mixture of amine groups and grafted polymer. The results indicate that the exposure of the amine groups on the surface decreased as the molecular weight of the polymer increased. The hydrodynamic diameters correlated with PEG graft molecular weight and were in agreement with a distributed density model for the thickness of a polymer shell end-grafted to a particle core. This indicates that the particles obtained consist of single iron oxide cores coated with a polymer brush. Particle surface charge and hydrodynamic diameter were measured as a function of pH, ionic strength, and in biological buffers and cell culture media. DLVO theory was used to analyze the particle stability considering electrostatic, magnetic, steric, and van der Waals interactions. Experimental results and colloidal stability theory indicated that stability changes from electrostatically mediated for a graft molecular weight of 750g/mol to sterically mediated at molecular weights of 1000g/mol and above. These results indicate that a graft molecular weight above 1000g/mol is needed to produce particles that are stable in a wide range of pH and ionic strength, and in cell culture media.