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Biomimetic Synthesis of Gelatin Polypeptide-Assisted Noble-Metal Nanoparticles and Their Interaction Study

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ABSTRACT

Herein, the generation of gold, silver, and silver–gold (Ag–Au) bimetallic nanoparticles was carried out in collagen (gelatin) solution. It first showed that the major ingredient in gelatin polypeptide, glutamic acid, acted as reducing agent to biomimetically synthesize noble metal nanoparticles at 80°C. The size of nanoparticles can be controlled not only by the mass ratio of gelatin to gold ion but also by pH of gelatin solution. Interaction between noble-metal nanoparticles and polypeptide has been investigated by TEM, UV–visible, fluorescence spectroscopy, and HNMR. This study testified that the degradation of gelatin protein could not alter the morphology of nanoparticles, but it made nanoparticles aggregated clusters array (opposing three-dimensional α-helix folding structure) into isolated nanoparticles stabilized by gelatin residues. This is a promising merit of gelatin to apply in the synthesis of nanoparticles. Therefore, gelatin protein is an excellent template for biomimetic synthesis of noble metal/bimetallic nanoparticle growth to form nanometer-sized device.

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a TEM image of gelatin-AgNPs synthesized at 90°C (Cgelatin: 0.4 wt%, : 2 mL); b XRD of gelatin-AgNPs power obtained from the sample in a; c TEM image of gelatin-AgNPs synthesized at 90°C (Cgelatin: 0.4 wt%, : 4 mL). AgNO3 was added in gelatin solution in two times. At first, 0.2 mL AgNO3 was added. The other AgNO3 was added into reaction mixture after 10 h.
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Figure 10: a TEM image of gelatin-AgNPs synthesized at 90°C (Cgelatin: 0.4 wt%, : 2 mL); b XRD of gelatin-AgNPs power obtained from the sample in a; c TEM image of gelatin-AgNPs synthesized at 90°C (Cgelatin: 0.4 wt%, : 4 mL). AgNO3 was added in gelatin solution in two times. At first, 0.2 mL AgNO3 was added. The other AgNO3 was added into reaction mixture after 10 h.

Mentions: Figure 10a showed that spherical AgNPs could be prepared by using gelatin polypeptide as reducing and stabilizing agent. The large face on the gelatin-directed silver crystals is (111), verified by XRD (see Figure 10b). The (111) family of faces is those with the fewest number of broken bonds per atom and the lowest surface energy. That is, bringing in another silver atom from the gelatin solution above the silver–water interface to the growing crystal is least energetically favored at the (111) faces. Most face-centered cubic (fcc) metals, including gold, silver have cuboctahedral equilibrium shape with (111) facets that have a slightly lower surface energy than the (100) facets, reflected as (111) facets having a slightly larger area than (100) facets. At present, it is widely accepted that controlling the shape of metal nanoparticles in liquid media requires the use of an appropriate seed or soft structure–directing agent such as surfactant, stabilizer, and foreign metal ion [34]. Therefore, we synthesized non-spherical AgNPs and AuNPs by controlling the crystal facet growth. Figure 10c showed non-spherical AgNPs was formed by adding AgNO3 into gelatin solution in two times. The AgNPs formed in the first step was used as silver seeds.


Biomimetic Synthesis of Gelatin Polypeptide-Assisted Noble-Metal Nanoparticles and Their Interaction Study
a TEM image of gelatin-AgNPs synthesized at 90°C (Cgelatin: 0.4 wt%, : 2 mL); b XRD of gelatin-AgNPs power obtained from the sample in a; c TEM image of gelatin-AgNPs synthesized at 90°C (Cgelatin: 0.4 wt%, : 4 mL). AgNO3 was added in gelatin solution in two times. At first, 0.2 mL AgNO3 was added. The other AgNO3 was added into reaction mixture after 10 h.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3211277&req=5

Figure 10: a TEM image of gelatin-AgNPs synthesized at 90°C (Cgelatin: 0.4 wt%, : 2 mL); b XRD of gelatin-AgNPs power obtained from the sample in a; c TEM image of gelatin-AgNPs synthesized at 90°C (Cgelatin: 0.4 wt%, : 4 mL). AgNO3 was added in gelatin solution in two times. At first, 0.2 mL AgNO3 was added. The other AgNO3 was added into reaction mixture after 10 h.
Mentions: Figure 10a showed that spherical AgNPs could be prepared by using gelatin polypeptide as reducing and stabilizing agent. The large face on the gelatin-directed silver crystals is (111), verified by XRD (see Figure 10b). The (111) family of faces is those with the fewest number of broken bonds per atom and the lowest surface energy. That is, bringing in another silver atom from the gelatin solution above the silver–water interface to the growing crystal is least energetically favored at the (111) faces. Most face-centered cubic (fcc) metals, including gold, silver have cuboctahedral equilibrium shape with (111) facets that have a slightly lower surface energy than the (100) facets, reflected as (111) facets having a slightly larger area than (100) facets. At present, it is widely accepted that controlling the shape of metal nanoparticles in liquid media requires the use of an appropriate seed or soft structure–directing agent such as surfactant, stabilizer, and foreign metal ion [34]. Therefore, we synthesized non-spherical AgNPs and AuNPs by controlling the crystal facet growth. Figure 10c showed non-spherical AgNPs was formed by adding AgNO3 into gelatin solution in two times. The AgNPs formed in the first step was used as silver seeds.

View Article: PubMed Central - HTML - PubMed

ABSTRACT

Herein, the generation of gold, silver, and silver–gold (Ag–Au) bimetallic nanoparticles was carried out in collagen (gelatin) solution. It first showed that the major ingredient in gelatin polypeptide, glutamic acid, acted as reducing agent to biomimetically synthesize noble metal nanoparticles at 80°C. The size of nanoparticles can be controlled not only by the mass ratio of gelatin to gold ion but also by pH of gelatin solution. Interaction between noble-metal nanoparticles and polypeptide has been investigated by TEM, UV–visible, fluorescence spectroscopy, and HNMR. This study testified that the degradation of gelatin protein could not alter the morphology of nanoparticles, but it made nanoparticles aggregated clusters array (opposing three-dimensional α-helix folding structure) into isolated nanoparticles stabilized by gelatin residues. This is a promising merit of gelatin to apply in the synthesis of nanoparticles. Therefore, gelatin protein is an excellent template for biomimetic synthesis of noble metal/bimetallic nanoparticle growth to form nanometer-sized device.

No MeSH data available.