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Graphene oxide-modified ZnO particles: synthesis, characterization, and antibacterial properties.

Zhong L, Yun K - Int J Nanomedicine (2015)

Bottom Line: The morphology of the graphene oxide sheets and ZnO particles was confirmed with field emission scanning electron microscopy and biological atomic force microscopy.Enhanced electrochemical properties were detected with cyclic voltammetry, with a redox peak of the composites at 0.025 mV.After further study of the antibacterial mechanism, we concluded that a vast number of reactive oxygen species formed on the surface of composites, improving antibacterial properties.

View Article: PubMed Central - PubMed

Affiliation: Department of Bionanotechnology, Gachon University, Gyeonggi-do, Republic of Korea.

ABSTRACT
Nanosized ZnO particles with diameters of 15 nm were prepared with a solution precipitation method at low cost and high yield. The synthesis of the particles was functionalized by the organic solvent dimethylformamide, and the particles were covalently bonded to the surface of graphene oxide. The morphology of the graphene oxide sheets and ZnO particles was confirmed with field emission scanning electron microscopy and biological atomic force microscopy. Fourier transform infrared spectroscopy and X-ray diffraction were used to analyze the physical and chemical properties of the ZnO/graphene oxide composites that differed from those of the individual components. Enhanced electrochemical properties were detected with cyclic voltammetry, with a redox peak of the composites at 0.025 mV. Excellent antibacterial activity of ZnO/graphene oxide composites was observed with a microdilution method in which minimum inhibitory concentrations of 6.25 µg/mL for Escherichia coli and Salmonella typhimurium, 12.5 µg/mL for Bacillus subtilis, and 25 µg/mL for Enterococcus faecalis. After further study of the antibacterial mechanism, we concluded that a vast number of reactive oxygen species formed on the surface of composites, improving antibacterial properties.

No MeSH data available.


Related in: MedlinePlus

Fluorescence images of Escherichia coli cell.Notes: (A) with only DCFH-DA for control; (B) with DCFH-DA in ZnO; (C) with DCFH-DA in graphene oxide; (D) with DCFH-DA in ZnO/graphene oxide.Abbreviations: DCFH-DA, 2′,7′-dichlorodihydrofluorescein diacetate; ZnO, zinc oxide.
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f13-ijn-10-079: Fluorescence images of Escherichia coli cell.Notes: (A) with only DCFH-DA for control; (B) with DCFH-DA in ZnO; (C) with DCFH-DA in graphene oxide; (D) with DCFH-DA in ZnO/graphene oxide.Abbreviations: DCFH-DA, 2′,7′-dichlorodihydrofluorescein diacetate; ZnO, zinc oxide.

Mentions: Antibacterial activity of ZnO/graphene oxide is attributed to the production of ROS, including singlet oxygen, hydroxyl radicals, superoxide ions, and hydrogen peroxide. To examine the production of ROS, we used the oxidant-sensing fluorescent probe DCFH-DA. DCFH-DA is a nonpolar dye that converted into the polar derivative DCFH by cellular esterases that are nonfluorescent but switched to highly fluorescent dichlorofluorescein when oxidized by intracellular ROS.39 The intensity of green fluorescence is proportional to the level of ROS. Figure 12 illustrates the emission spectra of E. coli broth incubated with samples after 12 hours, showing the emission peak at 520 nm after excitation at 485 nm. The E. coli broth without sample does not show the emission peak at 520 nm. The fluorescent intensity indicates that the ZnO/graphene oxide produced a higher level ROS compared to ZnO and graphene oxide components. Figure 13A displays widespread background green fluorescence, attributing to auto-oxidation by fluorescent microscopy. Figure 13B and C shows weaker green fluorescence, proving ZnO particle and graphene oxide components commonly produced low ROS.39 However, ZnO/graphene oxide composites present noticeable increasing green fluorescence in the E. coli cell. According to fluorescence test, we concluded ZnO/graphene oxide composites produced a significant increase in the ROS level.


Graphene oxide-modified ZnO particles: synthesis, characterization, and antibacterial properties.

Zhong L, Yun K - Int J Nanomedicine (2015)

Fluorescence images of Escherichia coli cell.Notes: (A) with only DCFH-DA for control; (B) with DCFH-DA in ZnO; (C) with DCFH-DA in graphene oxide; (D) with DCFH-DA in ZnO/graphene oxide.Abbreviations: DCFH-DA, 2′,7′-dichlorodihydrofluorescein diacetate; ZnO, zinc oxide.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4554433&req=5

f13-ijn-10-079: Fluorescence images of Escherichia coli cell.Notes: (A) with only DCFH-DA for control; (B) with DCFH-DA in ZnO; (C) with DCFH-DA in graphene oxide; (D) with DCFH-DA in ZnO/graphene oxide.Abbreviations: DCFH-DA, 2′,7′-dichlorodihydrofluorescein diacetate; ZnO, zinc oxide.
Mentions: Antibacterial activity of ZnO/graphene oxide is attributed to the production of ROS, including singlet oxygen, hydroxyl radicals, superoxide ions, and hydrogen peroxide. To examine the production of ROS, we used the oxidant-sensing fluorescent probe DCFH-DA. DCFH-DA is a nonpolar dye that converted into the polar derivative DCFH by cellular esterases that are nonfluorescent but switched to highly fluorescent dichlorofluorescein when oxidized by intracellular ROS.39 The intensity of green fluorescence is proportional to the level of ROS. Figure 12 illustrates the emission spectra of E. coli broth incubated with samples after 12 hours, showing the emission peak at 520 nm after excitation at 485 nm. The E. coli broth without sample does not show the emission peak at 520 nm. The fluorescent intensity indicates that the ZnO/graphene oxide produced a higher level ROS compared to ZnO and graphene oxide components. Figure 13A displays widespread background green fluorescence, attributing to auto-oxidation by fluorescent microscopy. Figure 13B and C shows weaker green fluorescence, proving ZnO particle and graphene oxide components commonly produced low ROS.39 However, ZnO/graphene oxide composites present noticeable increasing green fluorescence in the E. coli cell. According to fluorescence test, we concluded ZnO/graphene oxide composites produced a significant increase in the ROS level.

Bottom Line: The morphology of the graphene oxide sheets and ZnO particles was confirmed with field emission scanning electron microscopy and biological atomic force microscopy.Enhanced electrochemical properties were detected with cyclic voltammetry, with a redox peak of the composites at 0.025 mV.After further study of the antibacterial mechanism, we concluded that a vast number of reactive oxygen species formed on the surface of composites, improving antibacterial properties.

View Article: PubMed Central - PubMed

Affiliation: Department of Bionanotechnology, Gachon University, Gyeonggi-do, Republic of Korea.

ABSTRACT
Nanosized ZnO particles with diameters of 15 nm were prepared with a solution precipitation method at low cost and high yield. The synthesis of the particles was functionalized by the organic solvent dimethylformamide, and the particles were covalently bonded to the surface of graphene oxide. The morphology of the graphene oxide sheets and ZnO particles was confirmed with field emission scanning electron microscopy and biological atomic force microscopy. Fourier transform infrared spectroscopy and X-ray diffraction were used to analyze the physical and chemical properties of the ZnO/graphene oxide composites that differed from those of the individual components. Enhanced electrochemical properties were detected with cyclic voltammetry, with a redox peak of the composites at 0.025 mV. Excellent antibacterial activity of ZnO/graphene oxide composites was observed with a microdilution method in which minimum inhibitory concentrations of 6.25 µg/mL for Escherichia coli and Salmonella typhimurium, 12.5 µg/mL for Bacillus subtilis, and 25 µg/mL for Enterococcus faecalis. After further study of the antibacterial mechanism, we concluded that a vast number of reactive oxygen species formed on the surface of composites, improving antibacterial properties.

No MeSH data available.


Related in: MedlinePlus