Relaxometric Studies of 纬-Fe2O3@SiO2 Core Shell Nanoparticles: When the Coating Matters

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• 作者：Sonia L. C. Pinho ; Sophie Laurent ; Jo茫o Rocha ; Alain Roch ; Marie-H茅l猫ne Delville ; St茅phane Mornet ; Luis D. Carlos ; Luce Vander Elst ; Robert N. Muller ; Carlos F. G. C. Geraldes
• 刊名：The Journal of Physical Chemistry C
• 出版年：2012
• 出版时间：January 26, 2012
• 年：2012
• 卷：116
• 期：3
• 页码：2285-2291
• 全文大小：439K
• 年卷期：v.116,no.3(January 26, 2012)
• ISSN：1932-7455

文摘

Iron oxide nanoparticles with a constant superparamagnetic core coated with a silica shell with a thickness ranging from 0.6 to 71 nm were prepared by a fast and facile soft chemistry approach. The increase of the coating thickness of the 纬-Fe₂O₃@SiO₂ nanoparticles causes a significant decrease of the r₁ and r₂ relaxivities of their aqueous suspensions. The sizes of the nanoparticles obtained by relaxometry are significantly lower than those measured by electron microscopy. Their magnetizations measured by relaxometry also decrease relative to the values obtained by magnetometry, which correspond to the core. However, this 鈥渕agnetic dilution鈥?is smaller than expected if the entire silica shell was water impermeable. Both results indicate that a significant part of the silica coating is permeable to water. The adequate silica shell thickness may, thus, be tuned to allow for both a sufficiently high response as contrast agent and an adequate grafting of targeted biomolecules.