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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 coated with L-serine.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-serine coated or uncoated samples at pH 5.5, 6.0, and 6.5, respectively.
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f3-ijn-9-029: Zeta potential and hydrodynamic size of silica nanoparticles coated with L-serine.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-serine coated or uncoated samples at pH 5.5, 6.0, and 6.5, respectively.

Mentions: Figure 3 represents the time- and pH-dependent changes in the zeta potentials and hydrodynamic sizes of SiO2EN20(S) and SiO2EN100(S). At pH 5.5, the 20 nm colloidal silica showed no significant change in its zeta potential. On the other hand, the zeta potential value increased by approximately 10 mV upon L-ser treatment in pH 6.0 and 6.5 (Figure 3A). Although the overall maximum hydrodynamic size increased to 28 nm at pH 6.5, no serious agglomeration or aggregation was observed. The average hydrodynamic size of the 20 nm silica was maintained at approximately 25 nm across the pH range. The 100 nm colloidal silica also showed a similar pattern in terms of the zeta potential and hydrodynamic size. At pH 5.5, the zeta potential value was not significantly changed after coating while approximately 10 and 15 mV zeta potential increases were observed at pH 6.0 and 6.5, respectively. The hydrodynamic size showed a slight increase from approximately 95 nm (uncoated) to 110–115 nm right after the coating reaction, but the hydrodynamic size gradually recovered its original value with increasing time, suggesting that the L-ser coated SiO2EN100(−) restored its colloidal stability.


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 coated with L-serine.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-serine 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

f3-ijn-9-029: Zeta potential and hydrodynamic size of silica nanoparticles coated with L-serine.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-serine coated or uncoated samples at pH 5.5, 6.0, and 6.5, respectively.
Mentions: Figure 3 represents the time- and pH-dependent changes in the zeta potentials and hydrodynamic sizes of SiO2EN20(S) and SiO2EN100(S). At pH 5.5, the 20 nm colloidal silica showed no significant change in its zeta potential. On the other hand, the zeta potential value increased by approximately 10 mV upon L-ser treatment in pH 6.0 and 6.5 (Figure 3A). Although the overall maximum hydrodynamic size increased to 28 nm at pH 6.5, no serious agglomeration or aggregation was observed. The average hydrodynamic size of the 20 nm silica was maintained at approximately 25 nm across the pH range. The 100 nm colloidal silica also showed a similar pattern in terms of the zeta potential and hydrodynamic size. At pH 5.5, the zeta potential value was not significantly changed after coating while approximately 10 and 15 mV zeta potential increases were observed at pH 6.0 and 6.5, respectively. The hydrodynamic size showed a slight increase from approximately 95 nm (uncoated) to 110–115 nm right after the coating reaction, but the hydrodynamic size gradually recovered its original value with increasing time, suggesting that the L-ser coated SiO2EN100(−) restored its colloidal stability.

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.