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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) UV visible spectra and (B) particle size distribution of protein-capped and bare silver nanoparticles.
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pone.0134337.g005: (A) UV visible spectra and (B) particle size distribution of protein-capped and bare silver nanoparticles.

Mentions: The removal of protein shell by SDS treatment reduced the size of nanoparticles as reflected by the blue shift observed in the SPR peak from 429 to 425 nm in case of bare silver nanoparticle (Fig 5A). Calzolai et al. [42] reported a similar observation while studying interaction between human ubiquitin and gold nanoparticles. Furthermore, hydrodynamic particle size distribution and polydispersity index (PDI) analysis was carried out to investigate the occupancy of protein shell in case of protein-capped silver nanoparticles. The protein-capped silver nanoparticles showed a mean particle size of 90.53 nm (PDI = 0.357) which decreased to 58.39 nm (PDI = 0.396) in case of bare silver nanoparticles indicating the successful removal of protein shell from nanoparticles after SDS treatment (Fig 5B). The plausible reason for multi-layered shell (~32 nm thick) could be the non-specific and non-competitive binding of proteins present in the surrounding environment (reaction medium). The persistence of thick protein shell on biogenic silver nanoparticles has attracted our attention to compare the antibacterial efficacy of protein-capped nanoparticles in comparison to 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)

(A) UV visible spectra and (B) particle size distribution of protein-capped and bare silver nanoparticles.
© Copyright Policy
Related In: Results  -  Collection

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

pone.0134337.g005: (A) UV visible spectra and (B) particle size distribution of protein-capped and bare silver nanoparticles.
Mentions: The removal of protein shell by SDS treatment reduced the size of nanoparticles as reflected by the blue shift observed in the SPR peak from 429 to 425 nm in case of bare silver nanoparticle (Fig 5A). Calzolai et al. [42] reported a similar observation while studying interaction between human ubiquitin and gold nanoparticles. Furthermore, hydrodynamic particle size distribution and polydispersity index (PDI) analysis was carried out to investigate the occupancy of protein shell in case of protein-capped silver nanoparticles. The protein-capped silver nanoparticles showed a mean particle size of 90.53 nm (PDI = 0.357) which decreased to 58.39 nm (PDI = 0.396) in case of bare silver nanoparticles indicating the successful removal of protein shell from nanoparticles after SDS treatment (Fig 5B). The plausible reason for multi-layered shell (~32 nm thick) could be the non-specific and non-competitive binding of proteins present in the surrounding environment (reaction medium). The persistence of thick protein shell on biogenic silver nanoparticles has attracted our attention to compare the antibacterial efficacy of protein-capped nanoparticles in comparison to 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