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Synthesis and Characterization of Gelatin-Based Magnetic Hydrogels.

Helminger M, Wu B, Kollmann T, Benke D, Schwahn D, Pipich V, Faivre D, Zahn D, Cölfen H - Adv Funct Mater (2014)

Bottom Line: The magnetite structure characterization is supplemented by small-angle X-ray scattering and microscopy only visualizing magnetite.SANS shows an unchanged gelatin structure of average mesh size larger than the nanoparticles with respect to gel concentration while the magnetite nanoparticles size of around 10 nm seems to be limited by the gel mesh size.Overall, the simple and variable synthesis protocol, the cheap and easy accessibility of the components as well as the biocompatibility of the gelatin-based materials suggest them for a number of applications including actuators.

View Article: PubMed Central - PubMed

Affiliation: Physical Chemistry, University of Konstanz Universitätsstrasse 10, D-78457, Konstanz, Germany.

ABSTRACT

A simple preparation of thermoreversible gelatin-based ferrogels in water provides a constant structure defined by the crosslinking degree for gelatin contents between 6 and 18 wt%. The possibility of varying magnetite nanoparticle concentration between 20 and 70 wt% is also reported. Simulation studies hint at the suitability of collagen to bind iron and hydroxide ions, suggesting that collagen acts as a nucleation seed to iron hydroxide aggregation, and thus the intergrowth of collagen and magnetite nanoparticles already at the precursor stage. The detailed structure of the individual ferrogel components is characterized by small-angle neutron scattering (SANS) using contrast matching. The magnetite structure characterization is supplemented by small-angle X-ray scattering and microscopy only visualizing magnetite. SANS shows an unchanged gelatin structure of average mesh size larger than the nanoparticles with respect to gel concentration while the magnetite nanoparticles size of around 10 nm seems to be limited by the gel mesh size. Swelling measurements underline that magnetite acts as additional crosslinker and therefore varying the magnetic and mechanical properties of the ferrogels. Overall, the simple and variable synthesis protocol, the cheap and easy accessibility of the components as well as the biocompatibility of the gelatin-based materials suggest them for a number of applications including actuators.

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Schematic representation of the ferrogel synthesis. a) Unloaded gelatin hydrogel, b) hydrogel loaded with ferrous and ferric ions, and c) magnetic nanoparticles distributed inside the hydrogel after in situ co-precipitation with NaOH.
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fig-2: Schematic representation of the ferrogel synthesis. a) Unloaded gelatin hydrogel, b) hydrogel loaded with ferrous and ferric ions, and c) magnetic nanoparticles distributed inside the hydrogel after in situ co-precipitation with NaOH.

Mentions: Magnetic field-sensitive gels are called ferrogels. They can be synthesized through various procedures such as blending, in situ co-precipitation or grafting method.44 Here, we report an in situ mineralization protocol designed for the preparation of ferrogels consisting of biodegradable polymer gelatin and magnetic iron oxide nanoparticles. A three-step process was applied as schematically represented in Figure 2. In a first step, gelatin hydrogels were prepared at different biopolymer concentrations, ranging from 6 to 18 wt% to allow for different mesh sizes in the gelatin gels through concentration dependent variation of the crosslinking degree. These hydrogels were soaked in a solution of FeII (0.1 mol L−1) and FeIII (0.2 mol L−1) ions with a molar ratio of ferrous to ferric ions of 1:2 until they reached the swelling equilibrium. In a third step magnetite was formed inside the gelatin network after immersing the gel into a NaOH (0.1 mol L−1) solution, which did not affect the gel properties. The porous polymer network structure of the hydrogel in combination with the carbonyl, amine and anionic groups of the gelatin molecules binds the metal cations45 (see Section 2.7) and thereby acts as a template for co-precipitation of magnetic nanoparticles according to the following reaction:2


Synthesis and Characterization of Gelatin-Based Magnetic Hydrogels.

Helminger M, Wu B, Kollmann T, Benke D, Schwahn D, Pipich V, Faivre D, Zahn D, Cölfen H - Adv Funct Mater (2014)

Schematic representation of the ferrogel synthesis. a) Unloaded gelatin hydrogel, b) hydrogel loaded with ferrous and ferric ions, and c) magnetic nanoparticles distributed inside the hydrogel after in situ co-precipitation with NaOH.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4379906&req=5

fig-2: Schematic representation of the ferrogel synthesis. a) Unloaded gelatin hydrogel, b) hydrogel loaded with ferrous and ferric ions, and c) magnetic nanoparticles distributed inside the hydrogel after in situ co-precipitation with NaOH.
Mentions: Magnetic field-sensitive gels are called ferrogels. They can be synthesized through various procedures such as blending, in situ co-precipitation or grafting method.44 Here, we report an in situ mineralization protocol designed for the preparation of ferrogels consisting of biodegradable polymer gelatin and magnetic iron oxide nanoparticles. A three-step process was applied as schematically represented in Figure 2. In a first step, gelatin hydrogels were prepared at different biopolymer concentrations, ranging from 6 to 18 wt% to allow for different mesh sizes in the gelatin gels through concentration dependent variation of the crosslinking degree. These hydrogels were soaked in a solution of FeII (0.1 mol L−1) and FeIII (0.2 mol L−1) ions with a molar ratio of ferrous to ferric ions of 1:2 until they reached the swelling equilibrium. In a third step magnetite was formed inside the gelatin network after immersing the gel into a NaOH (0.1 mol L−1) solution, which did not affect the gel properties. The porous polymer network structure of the hydrogel in combination with the carbonyl, amine and anionic groups of the gelatin molecules binds the metal cations45 (see Section 2.7) and thereby acts as a template for co-precipitation of magnetic nanoparticles according to the following reaction:2

Bottom Line: The magnetite structure characterization is supplemented by small-angle X-ray scattering and microscopy only visualizing magnetite.SANS shows an unchanged gelatin structure of average mesh size larger than the nanoparticles with respect to gel concentration while the magnetite nanoparticles size of around 10 nm seems to be limited by the gel mesh size.Overall, the simple and variable synthesis protocol, the cheap and easy accessibility of the components as well as the biocompatibility of the gelatin-based materials suggest them for a number of applications including actuators.

View Article: PubMed Central - PubMed

Affiliation: Physical Chemistry, University of Konstanz Universitätsstrasse 10, D-78457, Konstanz, Germany.

ABSTRACT

A simple preparation of thermoreversible gelatin-based ferrogels in water provides a constant structure defined by the crosslinking degree for gelatin contents between 6 and 18 wt%. The possibility of varying magnetite nanoparticle concentration between 20 and 70 wt% is also reported. Simulation studies hint at the suitability of collagen to bind iron and hydroxide ions, suggesting that collagen acts as a nucleation seed to iron hydroxide aggregation, and thus the intergrowth of collagen and magnetite nanoparticles already at the precursor stage. The detailed structure of the individual ferrogel components is characterized by small-angle neutron scattering (SANS) using contrast matching. The magnetite structure characterization is supplemented by small-angle X-ray scattering and microscopy only visualizing magnetite. SANS shows an unchanged gelatin structure of average mesh size larger than the nanoparticles with respect to gel concentration while the magnetite nanoparticles size of around 10 nm seems to be limited by the gel mesh size. Swelling measurements underline that magnetite acts as additional crosslinker and therefore varying the magnetic and mechanical properties of the ferrogels. Overall, the simple and variable synthesis protocol, the cheap and easy accessibility of the components as well as the biocompatibility of the gelatin-based materials suggest them for a number of applications including actuators.

No MeSH data available.


Related in: MedlinePlus