Limits...
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.


13C nuclear magnetic resonance results for (a) ZnOSM20(−), (b) ZnOSM20(+), (c) ZnOAE100(−), and (d) ZnOAE100(+).Notes: As shown in Figure 5, (COO−) represents carboxyl carbon of L-serine and citrate; Cα and Cβ represent peaks of L-serine; Cq represents quaternary carbon of citrate; and 1–5 represent peaks of HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid).
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4279853&req=5

f4-ijn-9-041: 13C nuclear magnetic resonance results for (a) ZnOSM20(−), (b) ZnOSM20(+), (c) ZnOAE100(−), and (d) ZnOAE100(+).Notes: As shown in Figure 5, (COO−) represents carboxyl carbon of L-serine and citrate; Cα and Cβ represent peaks of L-serine; Cq represents quaternary carbon of citrate; and 1–5 represent peaks of HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid).

Mentions: Solid-state 13C nuclear magnetic resonance was used to verify the existence of surface-coating organic moieties, citrate and L-serine (Figure 4). As shown in Figure 5, the coating agents and the citrate, L-serine, and HEPES dispersants contain various carbon centers with different chemical environments, which were clearly distinguished in the nuclear magnetic resonance spectra. All four types of coated ZnO nanoparticles showed δ11(COO−) and δ22(COO−) peaks, and these were attributed to the carboxylates in citrate and L-serine.27,28 In the citrate-coated ZnO nanoparticles, the characteristic peak of the quaternary carbon (Cq) of citrate was found at 76.6 ppm, and C1, C2, C3, C4, and C5 peaks originating from HEPES were observed in the range of 50–60 ppm (Figure 4A–C).29 On the other hand, the nuclear magnetic resonance spectra for the L-serine-coated ZnO samples showed peaks at 63.2 ppm and 56.1 ppm, corresponding to the Cβ and Cα carbons in the amino acids.28 These results again confirmed that the C, O, and N peaks in XPS were attributable to the coating agents and dispersants.


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)

13C nuclear magnetic resonance results for (a) ZnOSM20(−), (b) ZnOSM20(+), (c) ZnOAE100(−), and (d) ZnOAE100(+).Notes: As shown in Figure 5, (COO−) represents carboxyl carbon of L-serine and citrate; Cα and Cβ represent peaks of L-serine; Cq represents quaternary carbon of citrate; and 1–5 represent peaks of HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid).
© Copyright Policy
Related In: Results  -  Collection

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

f4-ijn-9-041: 13C nuclear magnetic resonance results for (a) ZnOSM20(−), (b) ZnOSM20(+), (c) ZnOAE100(−), and (d) ZnOAE100(+).Notes: As shown in Figure 5, (COO−) represents carboxyl carbon of L-serine and citrate; Cα and Cβ represent peaks of L-serine; Cq represents quaternary carbon of citrate; and 1–5 represent peaks of HEPES (4-(2-hydroxyethyl)-1-piperazineethanesulfonic acid).
Mentions: Solid-state 13C nuclear magnetic resonance was used to verify the existence of surface-coating organic moieties, citrate and L-serine (Figure 4). As shown in Figure 5, the coating agents and the citrate, L-serine, and HEPES dispersants contain various carbon centers with different chemical environments, which were clearly distinguished in the nuclear magnetic resonance spectra. All four types of coated ZnO nanoparticles showed δ11(COO−) and δ22(COO−) peaks, and these were attributed to the carboxylates in citrate and L-serine.27,28 In the citrate-coated ZnO nanoparticles, the characteristic peak of the quaternary carbon (Cq) of citrate was found at 76.6 ppm, and C1, C2, C3, C4, and C5 peaks originating from HEPES were observed in the range of 50–60 ppm (Figure 4A–C).29 On the other hand, the nuclear magnetic resonance spectra for the L-serine-coated ZnO samples showed peaks at 63.2 ppm and 56.1 ppm, corresponding to the Cβ and Cα carbons in the amino acids.28 These results again confirmed that the C, O, and N peaks in XPS were attributable to the coating agents and dispersants.

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.