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Removal of Protein Capping Enhances the Antibacterial Efficiency of Biosynthesized Silver Nanoparticles.

Jain N, Bhargava A, Rathi M, Dilip RV, Panwar J - PLoS ONE (2015)

Bottom Line: The synthesized nanoparticles were found to be homogenous, spherical, mono-dispersed and covered with multi-layered protein shell.The results revealed that bare nanoparticles were more effective as compared to the protein-capped silver nanoparticles with varying antibacterial potential against the tested Gram positive and negative bacterial species.In conclusion, our results illustrate that presence of protein shell on silver nanoparticles can decrease their bactericidal effects.

View Article: PubMed Central - PubMed

Affiliation: Centre for Biotechnology, Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, 333 031, India.

ABSTRACT
The present study demonstrates an economical and environmental affable approach for the synthesis of "protein-capped" silver nanoparticles in aqueous solvent system. A variety of standard techniques viz. UV-visible spectroscopy, transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) measurements were employed to characterize the shape, size and composition of nanoparticles. The synthesized nanoparticles were found to be homogenous, spherical, mono-dispersed and covered with multi-layered protein shell. In order to prepare bare silver nanoparticles, the protein shell was removed from biogenic nanoparticles as confirmed by UV-visible spectroscopy, FTIR and photoluminescence analysis. Subsequently, the antibacterial efficacy of protein-capped and bare silver nanoparticles was compared by bacterial growth rate and minimum inhibitory concentration assay. The results revealed that bare nanoparticles were more effective as compared to the protein-capped silver nanoparticles with varying antibacterial potential against the tested Gram positive and negative bacterial species. Mechanistic studies based on ROS generation and membrane damage suggested that protein-capped and bare silver nanoparticles demonstrate distinct mode of action. These findings were strengthened by the TEM imaging along with silver ion release measurements using inductively coupled plasma atomic emission spectroscopy (ICP-AES). In conclusion, our results illustrate that presence of protein shell on silver nanoparticles can decrease their bactericidal effects. These findings open new avenues for surface modifications of nanoparticles to modulate and enhance their functional properties.

No MeSH data available.


Related in: MedlinePlus

(A) XRD spectrum of as-synthesized protein-capped silver nanoparticles with Bragg’s diffraction values shown in parentheses. (B) EDS spectrum showing the elemental composition of silver nanoparticles.
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pone.0134337.g003: (A) XRD spectrum of as-synthesized protein-capped silver nanoparticles with Bragg’s diffraction values shown in parentheses. (B) EDS spectrum showing the elemental composition of silver nanoparticles.

Mentions: X-ray diffraction pattern recorded by preparing drop-coated film of protein-capped silver nanoparticles further validated the crystalline nature of nanoparticles. The well-defined peaks at 2θ values of 38.03°, 46.18°, 64.60°, and 77.18° corresponds to (111), (200), (220) and (311) planes of silver, respectively (Fig 3A). These values were in complete agreement with the face-centered cubic (fcc) lattice structure of crystalline silver (JCPDS file no. 04–0783). A similar pattern of XRD spectrum has been reported for metallic silver nanoparticles synthesized by other fungi [41]. EDS was carried out to determine the elemental composition of as-synthesized nanoparticles and capping molecules. An intense optical absorption band at 3.0 KeV confirmed the presence of pure metallic silver nanoparticles (Fig 3B). Other peaks observed for C, N and O atoms indicated the presence of proteins as capping molecules.


Removal of Protein Capping Enhances the Antibacterial Efficiency of Biosynthesized Silver Nanoparticles.

Jain N, Bhargava A, Rathi M, Dilip RV, Panwar J - PLoS ONE (2015)

(A) XRD spectrum of as-synthesized protein-capped silver nanoparticles with Bragg’s diffraction values shown in parentheses. (B) EDS spectrum showing the elemental composition of silver nanoparticles.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4520467&req=5

pone.0134337.g003: (A) XRD spectrum of as-synthesized protein-capped silver nanoparticles with Bragg’s diffraction values shown in parentheses. (B) EDS spectrum showing the elemental composition of silver nanoparticles.
Mentions: X-ray diffraction pattern recorded by preparing drop-coated film of protein-capped silver nanoparticles further validated the crystalline nature of nanoparticles. The well-defined peaks at 2θ values of 38.03°, 46.18°, 64.60°, and 77.18° corresponds to (111), (200), (220) and (311) planes of silver, respectively (Fig 3A). These values were in complete agreement with the face-centered cubic (fcc) lattice structure of crystalline silver (JCPDS file no. 04–0783). A similar pattern of XRD spectrum has been reported for metallic silver nanoparticles synthesized by other fungi [41]. EDS was carried out to determine the elemental composition of as-synthesized nanoparticles and capping molecules. An intense optical absorption band at 3.0 KeV confirmed the presence of pure metallic silver nanoparticles (Fig 3B). Other peaks observed for C, N and O atoms indicated the presence of proteins as capping molecules.

Bottom Line: The synthesized nanoparticles were found to be homogenous, spherical, mono-dispersed and covered with multi-layered protein shell.The results revealed that bare nanoparticles were more effective as compared to the protein-capped silver nanoparticles with varying antibacterial potential against the tested Gram positive and negative bacterial species.In conclusion, our results illustrate that presence of protein shell on silver nanoparticles can decrease their bactericidal effects.

View Article: PubMed Central - PubMed

Affiliation: Centre for Biotechnology, Department of Biological Sciences, Birla Institute of Technology and Science, Pilani, 333 031, India.

ABSTRACT
The present study demonstrates an economical and environmental affable approach for the synthesis of "protein-capped" silver nanoparticles in aqueous solvent system. A variety of standard techniques viz. UV-visible spectroscopy, transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) measurements were employed to characterize the shape, size and composition of nanoparticles. The synthesized nanoparticles were found to be homogenous, spherical, mono-dispersed and covered with multi-layered protein shell. In order to prepare bare silver nanoparticles, the protein shell was removed from biogenic nanoparticles as confirmed by UV-visible spectroscopy, FTIR and photoluminescence analysis. Subsequently, the antibacterial efficacy of protein-capped and bare silver nanoparticles was compared by bacterial growth rate and minimum inhibitory concentration assay. The results revealed that bare nanoparticles were more effective as compared to the protein-capped silver nanoparticles with varying antibacterial potential against the tested Gram positive and negative bacterial species. Mechanistic studies based on ROS generation and membrane damage suggested that protein-capped and bare silver nanoparticles demonstrate distinct mode of action. These findings were strengthened by the TEM imaging along with silver ion release measurements using inductively coupled plasma atomic emission spectroscopy (ICP-AES). In conclusion, our results illustrate that presence of protein shell on silver nanoparticles can decrease their bactericidal effects. These findings open new avenues for surface modifications of nanoparticles to modulate and enhance their functional properties.

No MeSH data available.


Related in: MedlinePlus