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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.

No MeSH data available.


a Time evolution of the UV–vis spectra of gelatin-AuNPs synthesized at 80°C (Cgelatin: 0.4 wt%). The time intervals are (1) 10 min, (2) 20 min, (3) 40 min, (4) 60 min, (5) 80 min, (6) 100 min, (7) 120 min, (8) 140 min, (9) 160 min, (10) 180 min, (11) 240 min, (12) 360 min. The inset in a is digital images of gelatin-AuNPs (from left to right) corresponding to the curve 2, 3, 10, respectively; b TEM images of gelatin-AuNPs (curve 3), the inset in b is the TEM image of gelatin-AuNPs corresponding to the curve 10.
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Figure 5: a Time evolution of the UV–vis spectra of gelatin-AuNPs synthesized at 80°C (Cgelatin: 0.4 wt%). The time intervals are (1) 10 min, (2) 20 min, (3) 40 min, (4) 60 min, (5) 80 min, (6) 100 min, (7) 120 min, (8) 140 min, (9) 160 min, (10) 180 min, (11) 240 min, (12) 360 min. The inset in a is digital images of gelatin-AuNPs (from left to right) corresponding to the curve 2, 3, 10, respectively; b TEM images of gelatin-AuNPs (curve 3), the inset in b is the TEM image of gelatin-AuNPs corresponding to the curve 10.

Mentions: The interaction between the AuNPs and gelatin polypeptide chains at different stages was monitored by UV–vis absorption spectroscopy and TEM. As shown in Figure 5a, the intensity of the surface plasmon absorption increased with the increase in reaction time, which indicated the continued reduction of the metal ions with gelatin. The inset in Figure 5a showed the color of solution changed form light purple, purple into wine red, which indicated the nanoparticle morphology changing at different reaction stage. In addition, an obvious 25-nm blue shift from the surface plasmon absorption band of AuNPs with increased reaction time was observed. Figure 5b showed the initial stage of the reaction (Curve 3, 40 min), size of AuNPs with irregular shape at about 50–80 nm. The UV–vis absorption peak is about 550 nm. After this stage, complexes of gelatin-modified AuNPs changed into smaller particles stabilized by gelatin backbone (see the inset in Figure 5b). It maybe due to thermal dissociation of complexes of gelatin-modified AuNPs [15]. But the initial growth of nanoparticles by using gelatin polypeptide as reducing and stabilizing agent is not clear. The more rational scheme may be acquired by in situ SAXS and XANES using synchrotron radiation [28].


Biomimetic Synthesis of Gelatin Polypeptide-Assisted Noble-Metal Nanoparticles and Their Interaction Study
a Time evolution of the UV–vis spectra of gelatin-AuNPs synthesized at 80°C (Cgelatin: 0.4 wt%). The time intervals are (1) 10 min, (2) 20 min, (3) 40 min, (4) 60 min, (5) 80 min, (6) 100 min, (7) 120 min, (8) 140 min, (9) 160 min, (10) 180 min, (11) 240 min, (12) 360 min. The inset in a is digital images of gelatin-AuNPs (from left to right) corresponding to the curve 2, 3, 10, respectively; b TEM images of gelatin-AuNPs (curve 3), the inset in b is the TEM image of gelatin-AuNPs corresponding to the curve 10.
© Copyright Policy - open-access
Related In: Results  -  Collection

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getmorefigures.php?uid=PMC3211277&req=5

Figure 5: a Time evolution of the UV–vis spectra of gelatin-AuNPs synthesized at 80°C (Cgelatin: 0.4 wt%). The time intervals are (1) 10 min, (2) 20 min, (3) 40 min, (4) 60 min, (5) 80 min, (6) 100 min, (7) 120 min, (8) 140 min, (9) 160 min, (10) 180 min, (11) 240 min, (12) 360 min. The inset in a is digital images of gelatin-AuNPs (from left to right) corresponding to the curve 2, 3, 10, respectively; b TEM images of gelatin-AuNPs (curve 3), the inset in b is the TEM image of gelatin-AuNPs corresponding to the curve 10.
Mentions: The interaction between the AuNPs and gelatin polypeptide chains at different stages was monitored by UV–vis absorption spectroscopy and TEM. As shown in Figure 5a, the intensity of the surface plasmon absorption increased with the increase in reaction time, which indicated the continued reduction of the metal ions with gelatin. The inset in Figure 5a showed the color of solution changed form light purple, purple into wine red, which indicated the nanoparticle morphology changing at different reaction stage. In addition, an obvious 25-nm blue shift from the surface plasmon absorption band of AuNPs with increased reaction time was observed. Figure 5b showed the initial stage of the reaction (Curve 3, 40 min), size of AuNPs with irregular shape at about 50–80 nm. The UV–vis absorption peak is about 550 nm. After this stage, complexes of gelatin-modified AuNPs changed into smaller particles stabilized by gelatin backbone (see the inset in Figure 5b). It maybe due to thermal dissociation of complexes of gelatin-modified AuNPs [15]. But the initial growth of nanoparticles by using gelatin polypeptide as reducing and stabilizing agent is not clear. The more rational scheme may be acquired by in situ SAXS and XANES using synchrotron radiation [28].

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.