Abstract
Based on chelation effect between iron ions and amino groups of chitosan, in situ mineralization of magnetite nanoparticles in chitosan hydrogel under ambient conditions was proposed. The chelation effect between iron ions and amino groups in CS–Fe complex, which led to that chitosan hydrogel exerted a crucial control on the magnetite mineralization, was proved by X-ray photoelectron spectrum. The composition, morphology and size of the mineralized magnetite nanoparticles were characterized by X-ray diffraction, Raman spectroscopy, transmission electron microscopy and thermal gravity. The mineralized nanoparticles were nonstoichiometric magnetite with a unit formula of Fe2.85O4and coated by a thin layer of chitosan. The mineralized magnetite nanoparticles with mean diameter of 13 nm dispersed in chitosan hydrogel uniformly. Magnetization measurement indicated that superparamagnetism behavior was exhibited. These magnetite nanoparticles mineralized in chitosan hydrogel have potential applications in the field of biotechnology. Moreover, this method can also be used to synthesize other kinds of inorganic nanoparticles, such as ZnO, Fe2O3and hydroxyapatite.
Highlights
Mineralization, leading to the formation of minerals in the presence of organic molecules, is a widespread phenomenon in biological system [1, 2]
We propose in situ mineralization of magnetite nanoparticles in chitosan hydrogel under ambient conditions
This chelation effect of CS–Fe complex is the base of mineralization of magnetite in chitosan hydrogel, as demonstrated in this article
Summary
Mineralization, leading to the formation of minerals in the presence of organic molecules, is a widespread phenomenon in biological system [1, 2]. One of the most intriguing examples for mineralization is magnetic bacteria [4, 5]. Each magnetic bacteria acts as a small reaction vessel for mineralization, and the bacterial cell wall can control the iron ions diffusion. The mineralized magnetite nanoparticles in magnetic bacteria are water soluble and biocompatible, which makes it suitable for being used in the fields of bioscience and biomedicine, such as separation for purification and immunoassay [6], drug target delivery [7, 8], magnetic resonance imaging (MRI) [9, 10] and hyperthermia [11]. The yield of mineralization of magnetite nanoparticles in magnetic bacteria is too low to make it practical for industrial applications
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