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In vitro antibacterial activity of ZnO and Nd doped ZnO nanoparticles against ESBL producing Escherichia coli and Klebsiella pneumoniae.

Hameed AS, Karthikeyan C, Ahamed AP, Thajuddin N, Alharbi NS, Alharbi SA, Ravi G - Sci Rep (2016)

Bottom Line: The FT-IR spectra confirmed the Zn-O stretching bands at 422 and 451 cm(-1) for ZnO and Nd doped ZnO NPs respectively.From the UV-VIS spectroscopic measurement, the excitonic peaks were found around 373 nm and 380 nm for the respective samples.From confocal laser scanning microscopic (CLSM) analysis, the apoptotic nature of the cells was confirmed by the cell shrinkage, disorganization of cell wall and cell membrane and dead cell of the bacteria.

View Article: PubMed Central - PubMed

Affiliation: PG and Research Department of Physics, Jamal Mohamed College, Tiruchirappalli-620020, Tamil Nadu, India.

ABSTRACT
Pure ZnO and Neodymium (Nd) doped ZnO nanoparticles (NPs) were synthesized by the co-precipitation method. The synthesized nanoparticles retained the wurtzite hexagonal structure. From FESEM studies, ZnO and Nd doped ZnO NPs showed nanorod and nanoflower like morphology respectively. The FT-IR spectra confirmed the Zn-O stretching bands at 422 and 451 cm(-1) for ZnO and Nd doped ZnO NPs respectively. From the UV-VIS spectroscopic measurement, the excitonic peaks were found around 373 nm and 380 nm for the respective samples. The photoluminescence measurements revealed that the broad emission was composed of ten different bands due to zinc vacancies, oxygen vacancies and surface defects. The antibacterial studies performed against extended spectrum β-lactamases (ESBLs) producing strains of Escherichia coli and Klebsiella pneumoniae showed that the Nd doped ZnO NPs possessed a greater antibacterial effect than the pure ZnO NPs. From confocal laser scanning microscopic (CLSM) analysis, the apoptotic nature of the cells was confirmed by the cell shrinkage, disorganization of cell wall and cell membrane and dead cell of the bacteria. SEM analysis revealed the existence of bacterial loss of viability due to an impairment of cell membrane integrity, which was highly consistent with the damage of cell walls.

No MeSH data available.


Related in: MedlinePlus

Confocal micrographs of ESBL producing K. pneumoniae (a) Control, (b) treated with 1000 μg/mL of Nd doped ZnO NPs.
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f9: Confocal micrographs of ESBL producing K. pneumoniae (a) Control, (b) treated with 1000 μg/mL of Nd doped ZnO NPs.

Mentions: The effect of Nd doped ZnO nanoparticles on the viability of E. coli and K. pneumoniae strains were studied by confocal laser scanning microscopy (CLSM) in the presence of Acridine orange/Ethidium Bromide (AO/EB) staining. It should be noted that in AO/ EB, Acridine orange stains both live and dead cells. Ethidium bromide stains only cells that have lost membrane integrity, i.e., EB permeates only cells which lost membrane integrity. Live cells appear as green in colour and dead cells appear as red in colour. The nanoparticles prepared in this study have the small particle sizes and thus cause the bacteria to coagulate in nanoparticle suspensions making it challenging to observe individual bacterium. Figures 8(a,b and 9a,b) represent dual-stained cells at magnification of 60X of E. coli and K. pneumoniae strains untreated (control) and treated with (1000 μg/mL) Nd doped ZnO NPs. The results from the dual staining suggest that the Nd doped ZnO NPs treated cells are dead as compared to untreated E. coli and K. pneumoniae cells. The majority of the untreated cells showed a green fluorescence due to the viable or live cells, indicating intact cell wall structure, whereas only a small percentage of the untreated cells showed red fluorescence denoting dead cells with non-permeable cell wall or membrane structure. Figure 8(b) in contrast, the cells (almost 99%) treated with 1000 μg/mL of Nd doped ZnO NPs exhibited red fluorescence indicating dead cells. These results suggest that the treatment of E. coli strain with the Nd doped ZnO NPs leads to cell death and/or bacteriostatic effect, which coincides with the results determined by MIC through optical density measurement. But K. pneumoniae cells treated with 1000 μg/mL of Nd doped ZnO NPs (Fig. 9b) show a more apoptotic nature as well as cell shrinkage, disorganization of both cell wall and cell membrane and dead cell of the bacteria.


In vitro antibacterial activity of ZnO and Nd doped ZnO nanoparticles against ESBL producing Escherichia coli and Klebsiella pneumoniae.

Hameed AS, Karthikeyan C, Ahamed AP, Thajuddin N, Alharbi NS, Alharbi SA, Ravi G - Sci Rep (2016)

Confocal micrographs of ESBL producing K. pneumoniae (a) Control, (b) treated with 1000 μg/mL of Nd doped ZnO NPs.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4829841&req=5

f9: Confocal micrographs of ESBL producing K. pneumoniae (a) Control, (b) treated with 1000 μg/mL of Nd doped ZnO NPs.
Mentions: The effect of Nd doped ZnO nanoparticles on the viability of E. coli and K. pneumoniae strains were studied by confocal laser scanning microscopy (CLSM) in the presence of Acridine orange/Ethidium Bromide (AO/EB) staining. It should be noted that in AO/ EB, Acridine orange stains both live and dead cells. Ethidium bromide stains only cells that have lost membrane integrity, i.e., EB permeates only cells which lost membrane integrity. Live cells appear as green in colour and dead cells appear as red in colour. The nanoparticles prepared in this study have the small particle sizes and thus cause the bacteria to coagulate in nanoparticle suspensions making it challenging to observe individual bacterium. Figures 8(a,b and 9a,b) represent dual-stained cells at magnification of 60X of E. coli and K. pneumoniae strains untreated (control) and treated with (1000 μg/mL) Nd doped ZnO NPs. The results from the dual staining suggest that the Nd doped ZnO NPs treated cells are dead as compared to untreated E. coli and K. pneumoniae cells. The majority of the untreated cells showed a green fluorescence due to the viable or live cells, indicating intact cell wall structure, whereas only a small percentage of the untreated cells showed red fluorescence denoting dead cells with non-permeable cell wall or membrane structure. Figure 8(b) in contrast, the cells (almost 99%) treated with 1000 μg/mL of Nd doped ZnO NPs exhibited red fluorescence indicating dead cells. These results suggest that the treatment of E. coli strain with the Nd doped ZnO NPs leads to cell death and/or bacteriostatic effect, which coincides with the results determined by MIC through optical density measurement. But K. pneumoniae cells treated with 1000 μg/mL of Nd doped ZnO NPs (Fig. 9b) show a more apoptotic nature as well as cell shrinkage, disorganization of both cell wall and cell membrane and dead cell of the bacteria.

Bottom Line: The FT-IR spectra confirmed the Zn-O stretching bands at 422 and 451 cm(-1) for ZnO and Nd doped ZnO NPs respectively.From the UV-VIS spectroscopic measurement, the excitonic peaks were found around 373 nm and 380 nm for the respective samples.From confocal laser scanning microscopic (CLSM) analysis, the apoptotic nature of the cells was confirmed by the cell shrinkage, disorganization of cell wall and cell membrane and dead cell of the bacteria.

View Article: PubMed Central - PubMed

Affiliation: PG and Research Department of Physics, Jamal Mohamed College, Tiruchirappalli-620020, Tamil Nadu, India.

ABSTRACT
Pure ZnO and Neodymium (Nd) doped ZnO nanoparticles (NPs) were synthesized by the co-precipitation method. The synthesized nanoparticles retained the wurtzite hexagonal structure. From FESEM studies, ZnO and Nd doped ZnO NPs showed nanorod and nanoflower like morphology respectively. The FT-IR spectra confirmed the Zn-O stretching bands at 422 and 451 cm(-1) for ZnO and Nd doped ZnO NPs respectively. From the UV-VIS spectroscopic measurement, the excitonic peaks were found around 373 nm and 380 nm for the respective samples. The photoluminescence measurements revealed that the broad emission was composed of ten different bands due to zinc vacancies, oxygen vacancies and surface defects. The antibacterial studies performed against extended spectrum β-lactamases (ESBLs) producing strains of Escherichia coli and Klebsiella pneumoniae showed that the Nd doped ZnO NPs possessed a greater antibacterial effect than the pure ZnO NPs. From confocal laser scanning microscopic (CLSM) analysis, the apoptotic nature of the cells was confirmed by the cell shrinkage, disorganization of cell wall and cell membrane and dead cell of the bacteria. SEM analysis revealed the existence of bacterial loss of viability due to an impairment of cell membrane integrity, which was highly consistent with the damage of cell walls.

No MeSH data available.


Related in: MedlinePlus