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Antimicrobial activity of iron oxide nanoparticle upon modulation of nanoparticle-bacteria interface.

Arakha M, Pal S, Samantarrai D, Panigrahi TK, Mallick BC, Pramanik K, Mallick B, Jha S - Sci Rep (2015)

Bottom Line: Additionally, the nanocrystals obtained were found to have spherical size with 10-20 nm diameter.However, coating with chitosan molecule resulted significant increase in antimicrobial propensity of IONP.The data, altogether, indicated that the chitosan coating of IONP result in interface that enhances ROS production, hence the antimicrobial activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Science, National Institute of Technology Rourkela, Odisha 769008, India.

ABSTRACT
Investigating the interaction patterns at nano-bio interface is a key challenge for safe use of nanoparticles (NPs) to any biological system. The study intends to explore the role of interaction pattern at the iron oxide nanoparticle (IONP)-bacteria interface affecting antimicrobial propensity of IONP. To this end, IONP with magnetite like atomic arrangement and negative surface potential (n-IONP) was synthesized by co-precipitation method. Positively charged chitosan molecule coating was used to reverse the surface potential of n-IONP, i.e. positive surface potential IONP (p-IONP). The comparative data from fourier transform infrared spectroscope, XRD, and zeta potential analyzer indicated the successful coating of IONP surface with chitosan molecule. Additionally, the nanocrystals obtained were found to have spherical size with 10-20 nm diameter. The BacLight fluorescence assay, bacterial growth kinetic and colony forming unit studies indicated that n-IONP (<50 μM) has insignificant antimicrobial activity against Bacillus subtilis and Escherichia coli. However, coating with chitosan molecule resulted significant increase in antimicrobial propensity of IONP. Additionally, the assay to study reactive oxygen species (ROS) indicated relatively higher ROS production upon p-IONP treatment of the bacteria. The data, altogether, indicated that the chitosan coating of IONP result in interface that enhances ROS production, hence the antimicrobial activity.

No MeSH data available.


Related in: MedlinePlus

SEM micrographs showing membrane deformation/damage of B. subtilis upon p-IONP treatment.(a) SEM image of control (without p-IONP treatment), and figure inset shows the EDX spectra of B. subtilis surface. (b) SEM image of B. subtilis cells upon p-IONP treatment, and figure inset shows the EDX spectra of B. subtilis surface after p-IONP treatment.
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f7: SEM micrographs showing membrane deformation/damage of B. subtilis upon p-IONP treatment.(a) SEM image of control (without p-IONP treatment), and figure inset shows the EDX spectra of B. subtilis surface. (b) SEM image of B. subtilis cells upon p-IONP treatment, and figure inset shows the EDX spectra of B. subtilis surface after p-IONP treatment.

Mentions: OH° and HO2° formed in the process are free radicals. Iron in magnetite (Fe3O4) NP through a series of reactions is fully oxidized to maghemite (γ-Fe2O3) causing oxidative stress to bacterial cells, hence bacterial cell death. In contrast, fully oxidized maghemite is relatively stable in culture medium without any further possibility of electronic or ionic transition. Hence, maghemite formed as end product possesses insignificant in vitro cytotoxic propensity37. Nevertheless, the amount of free radicals formed in the oxido-reduction process are sufficient to put stress on the viable bacterial cells, causing non-viable cells. The amount of ROS produced at the nano-bacteria interface depolarizes the bacterial membranes, causing membrane damage as suggested by BacLight assay (Fig. 6) and in our work with ZnONP8. However, we have also checked the membrane depolarization of B. subtilis (Fig. 7) using Scanning Electron Microscopy (detail method for sample preparation is in supplementary information), and the interaction between p-IONP and bacteria was confirmed using Energy-dispersive X-ray spectroscope (EDX). Unlike control (inset of Fig. 7a), the EDX spectra of p-IONP treated bacterial surface shows the traces of Fe, confirming the interaction of p-IONP with bacteria catalyses the membrane depolarization (inset of Fig. 7b). Moreover, the bacterial membrane depolarization upon p-IONP treatment, as suggested by BacLight assay, was further confirmed and illustrated in SEM micrograph (Fig. 7). Figure 8 shows the proposed schematic model elucidating the detail mechanism described here to understand the antimicrobial activity followed by p-IONP. Although n-IONP has less antibacterial activity, the growth kinetic study, LIVE/DEAD BacLight assay, and ROS detection studies indicate that the surface modification n-IONP with chitosan makes it more toxic to bacterial cells due to relatively stronger attractive interaction at the interface. Additionally, the cytotoxicity assay using Alamar blue dye following the procedure adopted by Jha, S. et al.38 (method is in supplementary information, Fig. S2) demonstrated the cytocompatibilty nature of both the nanoparticles, IONP and chitosan coated IONP. The work along with the recently published work from our group, Arakha, M. et al. (Scientific Reports, 2015, 5, 09578) indicate that the interfacial potential is not only the determining factor for the bactericidal effects of nanoparticle. In addition to interfacial potential, the interacting functional group at the interface also contribute in the effect through regulating level os ROS production. Hence, adopting the optimized approach, the antibacterial propensity of IONP interface can be modulated using chitosan coating without changing the cytocompatible nature of the nanoparticle.


Antimicrobial activity of iron oxide nanoparticle upon modulation of nanoparticle-bacteria interface.

Arakha M, Pal S, Samantarrai D, Panigrahi TK, Mallick BC, Pramanik K, Mallick B, Jha S - Sci Rep (2015)

SEM micrographs showing membrane deformation/damage of B. subtilis upon p-IONP treatment.(a) SEM image of control (without p-IONP treatment), and figure inset shows the EDX spectra of B. subtilis surface. (b) SEM image of B. subtilis cells upon p-IONP treatment, and figure inset shows the EDX spectra of B. subtilis surface after p-IONP treatment.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4594095&req=5

f7: SEM micrographs showing membrane deformation/damage of B. subtilis upon p-IONP treatment.(a) SEM image of control (without p-IONP treatment), and figure inset shows the EDX spectra of B. subtilis surface. (b) SEM image of B. subtilis cells upon p-IONP treatment, and figure inset shows the EDX spectra of B. subtilis surface after p-IONP treatment.
Mentions: OH° and HO2° formed in the process are free radicals. Iron in magnetite (Fe3O4) NP through a series of reactions is fully oxidized to maghemite (γ-Fe2O3) causing oxidative stress to bacterial cells, hence bacterial cell death. In contrast, fully oxidized maghemite is relatively stable in culture medium without any further possibility of electronic or ionic transition. Hence, maghemite formed as end product possesses insignificant in vitro cytotoxic propensity37. Nevertheless, the amount of free radicals formed in the oxido-reduction process are sufficient to put stress on the viable bacterial cells, causing non-viable cells. The amount of ROS produced at the nano-bacteria interface depolarizes the bacterial membranes, causing membrane damage as suggested by BacLight assay (Fig. 6) and in our work with ZnONP8. However, we have also checked the membrane depolarization of B. subtilis (Fig. 7) using Scanning Electron Microscopy (detail method for sample preparation is in supplementary information), and the interaction between p-IONP and bacteria was confirmed using Energy-dispersive X-ray spectroscope (EDX). Unlike control (inset of Fig. 7a), the EDX spectra of p-IONP treated bacterial surface shows the traces of Fe, confirming the interaction of p-IONP with bacteria catalyses the membrane depolarization (inset of Fig. 7b). Moreover, the bacterial membrane depolarization upon p-IONP treatment, as suggested by BacLight assay, was further confirmed and illustrated in SEM micrograph (Fig. 7). Figure 8 shows the proposed schematic model elucidating the detail mechanism described here to understand the antimicrobial activity followed by p-IONP. Although n-IONP has less antibacterial activity, the growth kinetic study, LIVE/DEAD BacLight assay, and ROS detection studies indicate that the surface modification n-IONP with chitosan makes it more toxic to bacterial cells due to relatively stronger attractive interaction at the interface. Additionally, the cytotoxicity assay using Alamar blue dye following the procedure adopted by Jha, S. et al.38 (method is in supplementary information, Fig. S2) demonstrated the cytocompatibilty nature of both the nanoparticles, IONP and chitosan coated IONP. The work along with the recently published work from our group, Arakha, M. et al. (Scientific Reports, 2015, 5, 09578) indicate that the interfacial potential is not only the determining factor for the bactericidal effects of nanoparticle. In addition to interfacial potential, the interacting functional group at the interface also contribute in the effect through regulating level os ROS production. Hence, adopting the optimized approach, the antibacterial propensity of IONP interface can be modulated using chitosan coating without changing the cytocompatible nature of the nanoparticle.

Bottom Line: Additionally, the nanocrystals obtained were found to have spherical size with 10-20 nm diameter.However, coating with chitosan molecule resulted significant increase in antimicrobial propensity of IONP.The data, altogether, indicated that the chitosan coating of IONP result in interface that enhances ROS production, hence the antimicrobial activity.

View Article: PubMed Central - PubMed

Affiliation: Department of Life Science, National Institute of Technology Rourkela, Odisha 769008, India.

ABSTRACT
Investigating the interaction patterns at nano-bio interface is a key challenge for safe use of nanoparticles (NPs) to any biological system. The study intends to explore the role of interaction pattern at the iron oxide nanoparticle (IONP)-bacteria interface affecting antimicrobial propensity of IONP. To this end, IONP with magnetite like atomic arrangement and negative surface potential (n-IONP) was synthesized by co-precipitation method. Positively charged chitosan molecule coating was used to reverse the surface potential of n-IONP, i.e. positive surface potential IONP (p-IONP). The comparative data from fourier transform infrared spectroscope, XRD, and zeta potential analyzer indicated the successful coating of IONP surface with chitosan molecule. Additionally, the nanocrystals obtained were found to have spherical size with 10-20 nm diameter. The BacLight fluorescence assay, bacterial growth kinetic and colony forming unit studies indicated that n-IONP (<50 μM) has insignificant antimicrobial activity against Bacillus subtilis and Escherichia coli. However, coating with chitosan molecule resulted significant increase in antimicrobial propensity of IONP. Additionally, the assay to study reactive oxygen species (ROS) indicated relatively higher ROS production upon p-IONP treatment of the bacteria. The data, altogether, indicated that the chitosan coating of IONP result in interface that enhances ROS production, hence the antimicrobial activity.

No MeSH data available.


Related in: MedlinePlus