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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

Malondialdehyde (MDA) assay demonstrating the difference in membrane damage capability of protein-capped and bare silver nanoparticles.Vertical bars represent standard errors. Significant differences from control (p ≤ 0.05) are marked with asterisk.
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pone.0134337.g010: Malondialdehyde (MDA) assay demonstrating the difference in membrane damage capability of protein-capped and bare silver nanoparticles.Vertical bars represent standard errors. Significant differences from control (p ≤ 0.05) are marked with asterisk.

Mentions: The generation of free radicals such as peroxide, superoxide and hydroxyl ions by silver nanoparticles have been reported to exert lipid peroxidation and damage membrane integrity [9,50–52]. Furthermore, biochemical and proteomic studies strengthened the fact that silver nanoparticles resulted in an immediate dissipation of the proton motive force which causes de-energization of cell membrane and consequently cell death [53]. Keeping these facts in mind, the membrane damage studies were performed by measuring MDA content. In general, an increased MDA content was observed in all the tested bacterial species when exposed to silver nanoparticles (Fig 10). However, marginal difference was observed between protein-capped and bare silver nanoparticles.


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)

Malondialdehyde (MDA) assay demonstrating the difference in membrane damage capability of protein-capped and bare silver nanoparticles.Vertical bars represent standard errors. Significant differences from control (p ≤ 0.05) are marked with asterisk.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0134337.g010: Malondialdehyde (MDA) assay demonstrating the difference in membrane damage capability of protein-capped and bare silver nanoparticles.Vertical bars represent standard errors. Significant differences from control (p ≤ 0.05) are marked with asterisk.
Mentions: The generation of free radicals such as peroxide, superoxide and hydroxyl ions by silver nanoparticles have been reported to exert lipid peroxidation and damage membrane integrity [9,50–52]. Furthermore, biochemical and proteomic studies strengthened the fact that silver nanoparticles resulted in an immediate dissipation of the proton motive force which causes de-energization of cell membrane and consequently cell death [53]. Keeping these facts in mind, the membrane damage studies were performed by measuring MDA content. In general, an increased MDA content was observed in all the tested bacterial species when exposed to silver nanoparticles (Fig 10). However, marginal difference was observed between protein-capped and bare silver nanoparticles.

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