Iron oxyhydroxide colloids stabilized with polysaccharides

In Situ Synthesis of Magnetite Nanoparticles in Carrageenan Gels

“…It has been previously reported that κ-carrageenan stabilizes iron oxyhydroxides at higher Fe/polysaccharide ratio than either ι-or λ-carrageenan. 23 Also, it has been observed that iron stabilization decreases as the Fe/polysaccharide ratio increases, which is consistent with the higher average particle sizes found here at lower biopolymer concentrations. The addition of ferric ions to ι-carrageenan leads to the formation of a heterogeneous gel, with harder orange zones in a yellow soft matrix, while homogeneous and transparent yellow gels were obtained for κ-and λ-carrageenan.…”

“…The inset shows the whole vis-NIR spectrum, which is in agreement with the typical spectrum found for several iron oxides, including magnetite. 23,34 Although these spectroscopic results are consistent with magnetite nanoparticles undergoing oxidation, in the presence of carrageenan and at ambient conditions, they do not allow conclusions to be drawn as to the nature of the final iron oxide phase present in the gel.…”

“…23,24 Furthermore, specific studies have been carried out on the interaction of κ-carrageenan with several transition-metal oxides and a structural model has been proposed for the biomineralization of iron oxides in the presence of this polysaccharide. 23,25 As a result, the use of κ-carrageenan as coating for magnetic particles has been suggested in order to induce the formation of a self-assembled nanoreactor within which iron oxides nanoparticles are stabilized. 23 In this work, κ-, λ-, and ι-carrageenan have been used as a media for the synthesis of magnetite nanoparticles, and the morphology and chemical stability of the resulting nanocomposites toward oxidation have been investigated.…”

“…23,25 As a result, the use of κ-carrageenan as coating for magnetic particles has been suggested in order to induce the formation of a self-assembled nanoreactor within which iron oxides nanoparticles are stabilized. 23 In this work, κ-, λ-, and ι-carrageenan have been used as a media for the synthesis of magnetite nanoparticles, and the morphology and chemical stability of the resulting nanocomposites toward oxidation have been investigated. These biopolymers comprise a group of linear sulfated polysaccharides extracted from red seaweeds composed of a repeating disaccharide unit that differs in sulfate content/position as well as in the presence of an anhydrous bridge on one of the monomers (Figure 1).…”

Hybrid metal oxide@biopolymer materials precursors of metal oxides and metal oxide-carbon composites

“…57) And the situation can be even more complex when a mixture of polysaccharide is used, for example Fe 3 O 4 particles. 58) More rarely used polysaccharide like carrageenan, agarose or dextran should be more considered from this point of view, for examples, the type of carrageenan is reported to affect the size and shape of nanoparticles, 59), 60) and in the case YBa 2 Cu 3 O 7 , the use of dextran is reported to lead to a uniform crystal size and morphology and a macroporous structure. Even rarer are the studies comparing different biopolymers such as that on the preparation of ¡-Fe 2 O 3 in the presence of either dextran, agarose and gelatin where small differences in morphology and size are observed, but significantly different magnetic properties are identified.…”