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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

UV visible spectrum of reaction medium as a function of time (0, 12, 24, 48 and 72 h).Inset shows tubes containing fungal cell-free filtrate (a) without and (b) with silver nitrate solution after 72 h of reaction.
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pone.0134337.g001: UV visible spectrum of reaction medium as a function of time (0, 12, 24, 48 and 72 h).Inset shows tubes containing fungal cell-free filtrate (a) without and (b) with silver nitrate solution after 72 h of reaction.

Mentions: A gradual change in the colour of reaction medium (containing fungal cell-free filtrate and precursor silver ions) from colourless to reddish brown revealed a visual evidence for silver nanoparticle synthesis (Fig 1 inset). UV-visible spectrum showed a gradual increase in the absorbance at 429 nm with respect to time (Fig 1). The absorption maxima at 429 nm can be attributed to the surface plasmon resonance (SPR) vibrations of synthesized silver nanoparticles [37]. No further increase in absorbance was observed after 72 h of reaction (data not shown), which indicated the complete reduction of precursor silver ions in reaction medium. Stability of as-synthesized silver nanoparticles was monitored periodically for more than three months. It was observed that the nanoparticle solution was extremely stable at room temperature, with no evidence of particle aggregation as determined by UV-visible spectroscopy measurements.


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)

UV visible spectrum of reaction medium as a function of time (0, 12, 24, 48 and 72 h).Inset shows tubes containing fungal cell-free filtrate (a) without and (b) with silver nitrate solution after 72 h of reaction.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0134337.g001: UV visible spectrum of reaction medium as a function of time (0, 12, 24, 48 and 72 h).Inset shows tubes containing fungal cell-free filtrate (a) without and (b) with silver nitrate solution after 72 h of reaction.
Mentions: A gradual change in the colour of reaction medium (containing fungal cell-free filtrate and precursor silver ions) from colourless to reddish brown revealed a visual evidence for silver nanoparticle synthesis (Fig 1 inset). UV-visible spectrum showed a gradual increase in the absorbance at 429 nm with respect to time (Fig 1). The absorption maxima at 429 nm can be attributed to the surface plasmon resonance (SPR) vibrations of synthesized silver nanoparticles [37]. No further increase in absorbance was observed after 72 h of reaction (data not shown), which indicated the complete reduction of precursor silver ions in reaction medium. Stability of as-synthesized silver nanoparticles was monitored periodically for more than three months. It was observed that the nanoparticle solution was extremely stable at room temperature, with no evidence of particle aggregation as determined by UV-visible spectroscopy measurements.

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