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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 detailed structure of the individual ferrogel components is characterized by small-angle neutron scattering (SANS) using contrast matching.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

(left) Representative structure for FeIII(OH)3 coordination by collagen. Note that three carbonyl/hydroxyl groups are providing O·Fe salt bridges via one short (2.3 Å) and two weaker (2.6 Å) contacts. (right) FeII(OH)2 cluster coordination by collagen leading to distorted/incomplete octahedral coordination of FeII (the number of coordinating water molecules from the solvent varies from 0 to 2). Atom colors: Fe (yellow), O (red/green for solvent), H (white), N(blue) and C(grey).
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fig-9: (left) Representative structure for FeIII(OH)3 coordination by collagen. Note that three carbonyl/hydroxyl groups are providing O·Fe salt bridges via one short (2.3 Å) and two weaker (2.6 Å) contacts. (right) FeII(OH)2 cluster coordination by collagen leading to distorted/incomplete octahedral coordination of FeII (the number of coordinating water molecules from the solvent varies from 0 to 2). Atom colors: Fe (yellow), O (red/green for solvent), H (white), N(blue) and C(grey).

Mentions: We performed molecular simulation studies of Fe2+/Fe3+ and hydroxide ion association to a triple helical (Gly-Hyp-Pro)n peptide to characterize the interplay of collagen and inorganic nanoparticle formation on the molecular scale. To allow direct comparison, the collagen fragment and the simulation method is chosen in full analogy to earlier studies on calcium and phosphate ion association to collagen.63 From this, favorable association sites for both FeII(OH)2 and FeIII(OH)3 ion clusters were identified. Figure 9 illustrates representative constellations as observed for each species. It is noteworthy, that both precursors to magnetite bind to collagen via hydrogen bonds and salt bridges without distorting the triple helix. Instead, Fe(OH)x binds to carbonyl and hydroxyl groups which oxygen atoms tend to complete an octahedral coordination polyhedral for either Fe3+ and Fe2+ association. The close interplay of Fe(OH)x motifs and collagen as observed from molecular simulation hints at the suitability of collagen to bind iron and hydroxide ions (with the later only forming stable bonds in combination with iron ions). From this we conclude that collagen acts as a nucleation seed to iron hydroxide aggregation, and thus intergrowth of collagen and magnetite nanoparticles already at the precursor stage. Moreover, the TEM micrographs of the final magnetite-collagen composites indicate a structural alignment of the nanoparticles (Figure 3), which we attribute to magnetite nucleation along collagen fibers. This interplay of organic and inorganic components could give rise to hierarchical composites as observed for calcium phosphate–collagen based biominerals.64


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)

(left) Representative structure for FeIII(OH)3 coordination by collagen. Note that three carbonyl/hydroxyl groups are providing O·Fe salt bridges via one short (2.3 Å) and two weaker (2.6 Å) contacts. (right) FeII(OH)2 cluster coordination by collagen leading to distorted/incomplete octahedral coordination of FeII (the number of coordinating water molecules from the solvent varies from 0 to 2). Atom colors: Fe (yellow), O (red/green for solvent), H (white), N(blue) and C(grey).
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC4379906&req=5

fig-9: (left) Representative structure for FeIII(OH)3 coordination by collagen. Note that three carbonyl/hydroxyl groups are providing O·Fe salt bridges via one short (2.3 Å) and two weaker (2.6 Å) contacts. (right) FeII(OH)2 cluster coordination by collagen leading to distorted/incomplete octahedral coordination of FeII (the number of coordinating water molecules from the solvent varies from 0 to 2). Atom colors: Fe (yellow), O (red/green for solvent), H (white), N(blue) and C(grey).
Mentions: We performed molecular simulation studies of Fe2+/Fe3+ and hydroxide ion association to a triple helical (Gly-Hyp-Pro)n peptide to characterize the interplay of collagen and inorganic nanoparticle formation on the molecular scale. To allow direct comparison, the collagen fragment and the simulation method is chosen in full analogy to earlier studies on calcium and phosphate ion association to collagen.63 From this, favorable association sites for both FeII(OH)2 and FeIII(OH)3 ion clusters were identified. Figure 9 illustrates representative constellations as observed for each species. It is noteworthy, that both precursors to magnetite bind to collagen via hydrogen bonds and salt bridges without distorting the triple helix. Instead, Fe(OH)x binds to carbonyl and hydroxyl groups which oxygen atoms tend to complete an octahedral coordination polyhedral for either Fe3+ and Fe2+ association. The close interplay of Fe(OH)x motifs and collagen as observed from molecular simulation hints at the suitability of collagen to bind iron and hydroxide ions (with the later only forming stable bonds in combination with iron ions). From this we conclude that collagen acts as a nucleation seed to iron hydroxide aggregation, and thus intergrowth of collagen and magnetite nanoparticles already at the precursor stage. Moreover, the TEM micrographs of the final magnetite-collagen composites indicate a structural alignment of the nanoparticles (Figure 3), which we attribute to magnetite nucleation along collagen fibers. This interplay of organic and inorganic components could give rise to hierarchical composites as observed for calcium phosphate–collagen based biominerals.64

Bottom Line: The detailed structure of the individual ferrogel components is characterized by small-angle neutron scattering (SANS) using contrast matching.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