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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.


Properties of colloidal silica nanoparticle suspension.Notes: (A) Hydrodynamic size, (B) zeta potential depending on the pH of deionized water, (C) hydrodynamic size, and (D) zeta potential at pH 7.0±0.4 in deionized water for colloidal silica nanoparticle suspension with (a) 20 nm diameter and (b) 100 nm diameter. Errors bars are based on polydispersity index.
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f1-ijn-9-029: Properties of colloidal silica nanoparticle suspension.Notes: (A) Hydrodynamic size, (B) zeta potential depending on the pH of deionized water, (C) hydrodynamic size, and (D) zeta potential at pH 7.0±0.4 in deionized water for colloidal silica nanoparticle suspension with (a) 20 nm diameter and (b) 100 nm diameter. Errors bars are based on polydispersity index.

Mentions: The colloidal properties (eg, zeta potential, hydrodynamic size) of the as purchased colloidal silica nanoparticles are shown in Figure 1. SiO2EN20(−) and SiO2EN100(−), which were advertised to have average diameters of 20 nm and 100 nm, in fact, exhibited hydrodynamic sizes of approximately 23 nm and approximately 93 nm, respectively (Figure 1A). These results corresponded well with the previously reported primary particle size of the same silica nanoparticles observed via scanning electron microscopy and transmission electron microscopy.26 It is worth noting that this hydrodynamic size was maintained in the 3–13 pH range, suggesting that the colloidal stability of both silica nanoparticles was retained regardless of the pH value. Figure 1C shows the hydrodynamic size distribution of colloidal silica at a neutral pH (approximately 7) according to the intensity distribution pattern, showing a fairly narrow distribution with homogeneous sizes. The zeta potential of both the 20 and 100 nm colloidal silica nanoparticles showed a highly negative charge in the 3–13 pH range. Like most other nanoparticle colloids, the current colloidal silica nanoparticles exhibited pH dependent zeta potential values; the higher the pH, the more negative the zeta potential values. The zeta potential values of both SiO2EN20(−) and SiO2EN100(−) were maintained at −40 mV and −50 mV, respectively, in the 6–10 pH range. The zeta potential values at pH 7 (Figure 1D) had narrow distributions, and all the particles were determined to have negative surface charges.


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)

Properties of colloidal silica nanoparticle suspension.Notes: (A) Hydrodynamic size, (B) zeta potential depending on the pH of deionized water, (C) hydrodynamic size, and (D) zeta potential at pH 7.0±0.4 in deionized water for colloidal silica nanoparticle suspension with (a) 20 nm diameter and (b) 100 nm diameter. Errors bars are based on polydispersity index.
© Copyright Policy
Related In: Results  -  Collection

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

f1-ijn-9-029: Properties of colloidal silica nanoparticle suspension.Notes: (A) Hydrodynamic size, (B) zeta potential depending on the pH of deionized water, (C) hydrodynamic size, and (D) zeta potential at pH 7.0±0.4 in deionized water for colloidal silica nanoparticle suspension with (a) 20 nm diameter and (b) 100 nm diameter. Errors bars are based on polydispersity index.
Mentions: The colloidal properties (eg, zeta potential, hydrodynamic size) of the as purchased colloidal silica nanoparticles are shown in Figure 1. SiO2EN20(−) and SiO2EN100(−), which were advertised to have average diameters of 20 nm and 100 nm, in fact, exhibited hydrodynamic sizes of approximately 23 nm and approximately 93 nm, respectively (Figure 1A). These results corresponded well with the previously reported primary particle size of the same silica nanoparticles observed via scanning electron microscopy and transmission electron microscopy.26 It is worth noting that this hydrodynamic size was maintained in the 3–13 pH range, suggesting that the colloidal stability of both silica nanoparticles was retained regardless of the pH value. Figure 1C shows the hydrodynamic size distribution of colloidal silica at a neutral pH (approximately 7) according to the intensity distribution pattern, showing a fairly narrow distribution with homogeneous sizes. The zeta potential of both the 20 and 100 nm colloidal silica nanoparticles showed a highly negative charge in the 3–13 pH range. Like most other nanoparticle colloids, the current colloidal silica nanoparticles exhibited pH dependent zeta potential values; the higher the pH, the more negative the zeta potential values. The zeta potential values of both SiO2EN20(−) and SiO2EN100(−) were maintained at −40 mV and −50 mV, respectively, in the 6–10 pH range. The zeta potential values at pH 7 (Figure 1D) had narrow distributions, and all the particles were determined to have negative surface charges.

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.