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Physicochemical properties of surface charge-modified ZnO nanoparticles with different particle sizes.

Kim KM, Choi MH, Lee JK, Jeong J, Kim YR, Kim MK, Paek SM, Oh JM - Int J Nanomedicine (2014)

Bottom Line: The coating agents were determined to have attached to the ZnO surfaces through either electrostatic interaction or partial coordination bonding.Electrokinetic measurements showed that the surface charges of the ZnO nanoparticles were successfully modified to be negative (about -40 mV) or positive (about +25 mV).Although all the four types of ZnO nanoparticles showed some agglomeration when suspended in water according to dynamic light scattering analysis, they had clearly distinguishable particle size and surface charge parameters and well defined physicochemical properties.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Medical Chemistry, College of Science and Technology, Yonsei University, Gangwon-do, South Korea.

ABSTRACT
In this study, four types of standardized ZnO nanoparticles were prepared for assessment of their potential biological risk. Powder-phased ZnO nanoparticles with different particle sizes (20 nm and 100 nm) were coated with citrate or L-serine to induce a negative or positive surface charge, respectively. The four types of coated ZnO nanoparticles were subjected to physicochemical evaluation according to the guidelines published by the Organisation for Economic Cooperation and Development. All four samples had a well crystallized Wurtzite phase, with particle sizes of ∼30 nm and ∼70 nm after coating with organic molecules. The coating agents were determined to have attached to the ZnO surfaces through either electrostatic interaction or partial coordination bonding. Electrokinetic measurements showed that the surface charges of the ZnO nanoparticles were successfully modified to be negative (about -40 mV) or positive (about +25 mV). Although all the four types of ZnO nanoparticles showed some agglomeration when suspended in water according to dynamic light scattering analysis, they had clearly distinguishable particle size and surface charge parameters and well defined physicochemical properties.

No MeSH data available.


Powder X-ray diffraction patterns for (a) ZnOSM20(−), (b) ZnOSM20(+), (c) ZnOAE100(−), and (d) ZnOAE100(+).
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f1-ijn-9-041: Powder X-ray diffraction patterns for (a) ZnOSM20(−), (b) ZnOSM20(+), (c) ZnOAE100(−), and (d) ZnOAE100(+).

Mentions: According to the powder XRD patterns, all the coated ZnO nanoparticles showed a classic hexagonal crystal Wurtzite structure (JPCDS No 36–1451), with a highly crystalline phase. Characteristic peaks at 2θ=31.8°, 34.4°, 36.3°, 47.5°, 56.6°, 62.9°, and 67.9° were assigned to the (100), (002), (101), (102), (110), (103), and (112) lattice planes.21 The lattice parameters of the coated ZnO nanoparticles calculated from the 2θ values of the peaks were a=3.251 Å and c=5.206 Å, and corresponded well to those of the reference Wurtzite (a=3.249 Å and c=5.207 Å). Thus, it can be concluded that size and the surface coating process did not affect the crystalline phase of the ZnO nanoparticles. The peak intensity and width obtained from XRD patterns are related to the preferred growth of a certain crystal plane as well as the degree of crystallinity in solid crystalline materials. In small-sized materials like nanoparticles, the crystallinity or preferred growth is highly dependent on the particle size and morphology. Overall, the larger ZnO particles (ZnOAE100, ZnOAE100(−), and ZnOAE100(+)) showed 2.2-fold higher peak intensities than the smaller ZnO particles (ZnOSM20, ZnOSM20(−) and ZnOSM20(+), Figures 1 and S1), and this result coincides well with the results of our previous study.18 Additional information on the crystalline properties of the nanoparticles was obtained by calculating Scherrer’s equation, which is known to provide information on crystallite size along a certain lattice plane and crystalline size, as follows:22D=0.89λ/(βcosθ)where λ is the wavelength of the X-ray radiation, 0.89 is a constant, β is the full width at half maximum, and θ is the diffraction angle.


Physicochemical properties of surface charge-modified ZnO nanoparticles with different particle sizes.

Kim KM, Choi MH, Lee JK, Jeong J, Kim YR, Kim MK, Paek SM, Oh JM - Int J Nanomedicine (2014)

Powder X-ray diffraction patterns for (a) ZnOSM20(−), (b) ZnOSM20(+), (c) ZnOAE100(−), and (d) ZnOAE100(+).
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4279853&req=5

f1-ijn-9-041: Powder X-ray diffraction patterns for (a) ZnOSM20(−), (b) ZnOSM20(+), (c) ZnOAE100(−), and (d) ZnOAE100(+).
Mentions: According to the powder XRD patterns, all the coated ZnO nanoparticles showed a classic hexagonal crystal Wurtzite structure (JPCDS No 36–1451), with a highly crystalline phase. Characteristic peaks at 2θ=31.8°, 34.4°, 36.3°, 47.5°, 56.6°, 62.9°, and 67.9° were assigned to the (100), (002), (101), (102), (110), (103), and (112) lattice planes.21 The lattice parameters of the coated ZnO nanoparticles calculated from the 2θ values of the peaks were a=3.251 Å and c=5.206 Å, and corresponded well to those of the reference Wurtzite (a=3.249 Å and c=5.207 Å). Thus, it can be concluded that size and the surface coating process did not affect the crystalline phase of the ZnO nanoparticles. The peak intensity and width obtained from XRD patterns are related to the preferred growth of a certain crystal plane as well as the degree of crystallinity in solid crystalline materials. In small-sized materials like nanoparticles, the crystallinity or preferred growth is highly dependent on the particle size and morphology. Overall, the larger ZnO particles (ZnOAE100, ZnOAE100(−), and ZnOAE100(+)) showed 2.2-fold higher peak intensities than the smaller ZnO particles (ZnOSM20, ZnOSM20(−) and ZnOSM20(+), Figures 1 and S1), and this result coincides well with the results of our previous study.18 Additional information on the crystalline properties of the nanoparticles was obtained by calculating Scherrer’s equation, which is known to provide information on crystallite size along a certain lattice plane and crystalline size, as follows:22D=0.89λ/(βcosθ)where λ is the wavelength of the X-ray radiation, 0.89 is a constant, β is the full width at half maximum, and θ is the diffraction angle.

Bottom Line: The coating agents were determined to have attached to the ZnO surfaces through either electrostatic interaction or partial coordination bonding.Electrokinetic measurements showed that the surface charges of the ZnO nanoparticles were successfully modified to be negative (about -40 mV) or positive (about +25 mV).Although all the four types of ZnO nanoparticles showed some agglomeration when suspended in water according to dynamic light scattering analysis, they had clearly distinguishable particle size and surface charge parameters and well defined physicochemical properties.

View Article: PubMed Central - PubMed

Affiliation: Department of Chemistry and Medical Chemistry, College of Science and Technology, Yonsei University, Gangwon-do, South Korea.

ABSTRACT
In this study, four types of standardized ZnO nanoparticles were prepared for assessment of their potential biological risk. Powder-phased ZnO nanoparticles with different particle sizes (20 nm and 100 nm) were coated with citrate or L-serine to induce a negative or positive surface charge, respectively. The four types of coated ZnO nanoparticles were subjected to physicochemical evaluation according to the guidelines published by the Organisation for Economic Cooperation and Development. All four samples had a well crystallized Wurtzite phase, with particle sizes of ∼30 nm and ∼70 nm after coating with organic molecules. The coating agents were determined to have attached to the ZnO surfaces through either electrostatic interaction or partial coordination bonding. Electrokinetic measurements showed that the surface charges of the ZnO nanoparticles were successfully modified to be negative (about -40 mV) or positive (about +25 mV). Although all the four types of ZnO nanoparticles showed some agglomeration when suspended in water according to dynamic light scattering analysis, they had clearly distinguishable particle size and surface charge parameters and well defined physicochemical properties.

No MeSH data available.