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Surface treatment of silica nanoparticles for stable and charge-controlled colloidal silica.

Kim KM, Kim HM, Lee WJ, Lee CW, Kim TI, Lee JK, Jeong J, Paek SM, Oh JM - Int J Nanomedicine (2014)

Bottom Line: Amino acid coatings resulted in relatively stable silica colloids with a modified surface charge.The time dependent change in L-arginine coated colloidal silica was investigated by measuring the pattern of the backscattered light in a Turbiscan™.The results indicated that both the 20 nm and 100 nm L-arginine coated silica samples were fairly stable in terms of colloidal homogeneity, showing only slight coalescence and sedimentation.

View Article: PubMed Central - PubMed

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

ABSTRACT
An attempt was made to control the surface charge of colloidal silica nanoparticles with 20 nm and 100 nm diameters. Untreated silica nanoparticles were determined to be highly negatively charged and have stable hydrodynamic sizes in a wide pH range. To change the surface to a positively charged form, various coating agents, such as amine containing molecules, multivalent metal cation, or amino acids, were used to treat the colloidal silica nanoparticles. Molecules with chelating amine sites were determined to have high affinity with the silica surface to make agglomerations or gel-like networks. Amino acid coatings resulted in relatively stable silica colloids with a modified surface charge. Three amino acid moiety coatings (L-serine, L-histidine, and L-arginine) exhibited surface charge modifying efficacy of L-histidine > L-arginine > L-serine and hydrodynamic size preservation efficacy of L-serine > L-arginine > L-histidine. The time dependent change in L-arginine coated colloidal silica was investigated by measuring the pattern of the backscattered light in a Turbiscan™. The results indicated that both the 20 nm and 100 nm L-arginine coated silica samples were fairly stable in terms of colloidal homogeneity, showing only slight coalescence and sedimentation.

No MeSH data available.


Zeta potential and hydrodynamic size of silica nanoparticles with L-histidine.Notes: (A) Zeta potential of colloidal silica nanoparticles with 20 nm diameter, (B) hydrodynamic size of colloidal silica nanoparticles with 20 nm diameter, (C) zeta potential of colloidal silica nanoparticles with 100 nm diameter, and (D) hydrodynamic size of colloidal silica nanoparticles with 100 nm diameter at pH 5.5, 6.0, and 6.5, and pristine silica depending on the time, respectively. Open or solid squares/triangles/circles represent L-histidine coated or uncoated samples at pH 5.5, 6.0, and 6.5, respectively.
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f4-ijn-9-029: Zeta potential and hydrodynamic size of silica nanoparticles with L-histidine.Notes: (A) Zeta potential of colloidal silica nanoparticles with 20 nm diameter, (B) hydrodynamic size of colloidal silica nanoparticles with 20 nm diameter, (C) zeta potential of colloidal silica nanoparticles with 100 nm diameter, and (D) hydrodynamic size of colloidal silica nanoparticles with 100 nm diameter at pH 5.5, 6.0, and 6.5, and pristine silica depending on the time, respectively. Open or solid squares/triangles/circles represent L-histidine coated or uncoated samples at pH 5.5, 6.0, and 6.5, respectively.

Mentions: The time dependent zeta potentials and hydrodynamic sizes of SiO2EN20(H) and SiO2EN100(H) are shown in Figure 4. Experiments were also carried out with three different pH values: 5.5, 6.0, and 6.5. The 20 nm colloidal silica showed a significant increase in zeta potential at all the pH conditions tested (Figure 4A). The zeta potential increased to approximately 15, 20, and 15 mV at the 5.5, 6.0, and 6.5 pH conditions, respectively. The zeta potential increase was larger compared with that in the L-ser coated colloidal silica. Figure 4B shows that the hydrodynamic size clearly increased with time after L-his coating. While the average size before coating was approximately 25 nm regardless of pH, the hydrodynamic size increased after L-his coating, resulting in 38, 700, and 600 nm after 48 hours at pH 6.5, 6.0, and 5.5, respectively. It is worth noting that the hydrodynamic size of SiO2EN20(H) increased more than 30-fold at pH 6.0 and 6.5, suggesting the formation of large agglomerates. Similar to the 20 nm silica, the 100 nm silica showed a similar pattern in the zeta potential and hydrodynamic size with the L-his coating. The zeta potential of SiO2EN100(H) significantly increased after L-his coating (Figure 4C). The average differences in the zeta potential before and after coating were approximately 20, 25, and 20 mV for pH 5.5, 6.0, and 6.5, respectively. The hydrodynamic size of the 100 nm colloidal silica did not show a serious increase after L-his coating compared with the 20 nm silica, but SiO SiO2EN100(H) exhibited more than 20-fold (> 400 nm) size increase at pH 5.5, which was a relatively high degree of agglomeration compared with L-ser coating.


Surface treatment of silica nanoparticles for stable and charge-controlled colloidal silica.

Kim KM, Kim HM, Lee WJ, Lee CW, Kim TI, Lee JK, Jeong J, Paek SM, Oh JM - Int J Nanomedicine (2014)

Zeta potential and hydrodynamic size of silica nanoparticles with L-histidine.Notes: (A) Zeta potential of colloidal silica nanoparticles with 20 nm diameter, (B) hydrodynamic size of colloidal silica nanoparticles with 20 nm diameter, (C) zeta potential of colloidal silica nanoparticles with 100 nm diameter, and (D) hydrodynamic size of colloidal silica nanoparticles with 100 nm diameter at pH 5.5, 6.0, and 6.5, and pristine silica depending on the time, respectively. Open or solid squares/triangles/circles represent L-histidine coated or uncoated samples at pH 5.5, 6.0, and 6.5, respectively.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4279762&req=5

f4-ijn-9-029: Zeta potential and hydrodynamic size of silica nanoparticles with L-histidine.Notes: (A) Zeta potential of colloidal silica nanoparticles with 20 nm diameter, (B) hydrodynamic size of colloidal silica nanoparticles with 20 nm diameter, (C) zeta potential of colloidal silica nanoparticles with 100 nm diameter, and (D) hydrodynamic size of colloidal silica nanoparticles with 100 nm diameter at pH 5.5, 6.0, and 6.5, and pristine silica depending on the time, respectively. Open or solid squares/triangles/circles represent L-histidine coated or uncoated samples at pH 5.5, 6.0, and 6.5, respectively.
Mentions: The time dependent zeta potentials and hydrodynamic sizes of SiO2EN20(H) and SiO2EN100(H) are shown in Figure 4. Experiments were also carried out with three different pH values: 5.5, 6.0, and 6.5. The 20 nm colloidal silica showed a significant increase in zeta potential at all the pH conditions tested (Figure 4A). The zeta potential increased to approximately 15, 20, and 15 mV at the 5.5, 6.0, and 6.5 pH conditions, respectively. The zeta potential increase was larger compared with that in the L-ser coated colloidal silica. Figure 4B shows that the hydrodynamic size clearly increased with time after L-his coating. While the average size before coating was approximately 25 nm regardless of pH, the hydrodynamic size increased after L-his coating, resulting in 38, 700, and 600 nm after 48 hours at pH 6.5, 6.0, and 5.5, respectively. It is worth noting that the hydrodynamic size of SiO2EN20(H) increased more than 30-fold at pH 6.0 and 6.5, suggesting the formation of large agglomerates. Similar to the 20 nm silica, the 100 nm silica showed a similar pattern in the zeta potential and hydrodynamic size with the L-his coating. The zeta potential of SiO2EN100(H) significantly increased after L-his coating (Figure 4C). The average differences in the zeta potential before and after coating were approximately 20, 25, and 20 mV for pH 5.5, 6.0, and 6.5, respectively. The hydrodynamic size of the 100 nm colloidal silica did not show a serious increase after L-his coating compared with the 20 nm silica, but SiO SiO2EN100(H) exhibited more than 20-fold (> 400 nm) size increase at pH 5.5, which was a relatively high degree of agglomeration compared with L-ser coating.

Bottom Line: Amino acid coatings resulted in relatively stable silica colloids with a modified surface charge.The time dependent change in L-arginine coated colloidal silica was investigated by measuring the pattern of the backscattered light in a Turbiscan™.The results indicated that both the 20 nm and 100 nm L-arginine coated silica samples were fairly stable in terms of colloidal homogeneity, showing only slight coalescence and sedimentation.

View Article: PubMed Central - PubMed

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

ABSTRACT
An attempt was made to control the surface charge of colloidal silica nanoparticles with 20 nm and 100 nm diameters. Untreated silica nanoparticles were determined to be highly negatively charged and have stable hydrodynamic sizes in a wide pH range. To change the surface to a positively charged form, various coating agents, such as amine containing molecules, multivalent metal cation, or amino acids, were used to treat the colloidal silica nanoparticles. Molecules with chelating amine sites were determined to have high affinity with the silica surface to make agglomerations or gel-like networks. Amino acid coatings resulted in relatively stable silica colloids with a modified surface charge. Three amino acid moiety coatings (L-serine, L-histidine, and L-arginine) exhibited surface charge modifying efficacy of L-histidine > L-arginine > L-serine and hydrodynamic size preservation efficacy of L-serine > L-arginine > L-histidine. The time dependent change in L-arginine coated colloidal silica was investigated by measuring the pattern of the backscattered light in a Turbiscan™. The results indicated that both the 20 nm and 100 nm L-arginine coated silica samples were fairly stable in terms of colloidal homogeneity, showing only slight coalescence and sedimentation.

No MeSH data available.