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Stable oligomeric clusters of gold nanoparticles: preparation, size distribution, derivatization, and physical and biological properties.

Smithies O, Lawrence M, Testen A, Horne LP, Wilder J, Altenburg M, Bleasdale B, Maeda N, Koklic T - Langmuir (2014)

Bottom Line: The crude oligocluster preparations have narrow size distributions, and for most purposes do not require fractionation.The oligoclusters do not aggregate after ∼300-fold centrifugal-filter concentration, and at this high concentration are easily derivatized with a variety of thiol-containing reagents.Unlike conventional glutathione-capped nanoparticles of comparable gold content, large oligoclusters derivatized with glutathione do not aggregate at high concentrations in phosphate-buffered saline (PBS) or in the circulation when injected into mice.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Laboratory Medicine, and ‡Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.

ABSTRACT
Reducing dilute aqueous HAuCl4 with NaSCN under alkaline conditions produces 2-3 nm diameter yellow nanoparticles without the addition of extraneous capping agents. We here describe two very simple methods for producing highly stable oligomeric grape-like clusters (oligoclusters) of these small nanoparticles. The oligoclusters have well-controlled diameters ranging from ∼5 to ∼30 nm, depending mainly on the number of subunits in the cluster. Our first ["delay-time"] method controls the size of the oligoclusters by varying from seconds to hours the delay time between making the HAuCl4 alkaline and adding the reducing agent, NaSCN. Our second ["add-on"] method controls size by using yellow nanoparticles as seeds onto which varying amounts of gold derived from "hydroxylated gold", Na(+)[Au(OH4-x)Clx](-), are added-on catalytically in the presence of NaSCN. Possible reaction mechanisms and a simple kinetic model fitting the data are discussed. The crude oligocluster preparations have narrow size distributions, and for most purposes do not require fractionation. The oligoclusters do not aggregate after ∼300-fold centrifugal-filter concentration, and at this high concentration are easily derivatized with a variety of thiol-containing reagents. This allows rare or expensive derivatizing reagents to be used economically. Unlike conventional glutathione-capped nanoparticles of comparable gold content, large oligoclusters derivatized with glutathione do not aggregate at high concentrations in phosphate-buffered saline (PBS) or in the circulation when injected into mice. Mice receiving them intravenously show no visible signs of distress. Their sizes can be made small enough to allow their excretion in the urine or large enough to prevent them from crossing capillary basement membranes. They are directly visible in electron micrographs without enhancement, and can model the biological fate of protein-like macromolecules with controlled sizes and charges. The ease of derivatizing the oligoclusters makes them potentially useful for presenting pharmacological agents to different tissues while controlling escape of the reagents from the circulation.

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Related in: MedlinePlus

Hydrodynamic properties of oligoclusters prepared with differentdelay times. (A) Profiles of PBS elution from a Sephacryl S200 high-resolution10/30 column of (left to right): purified bovine IgG, 45 s delay-timeoligoclusters, bovine serum albumin, and 5 s delay-time oligoclusters. Kd, permeation coefficient; the numbers belowthe Kd’s and on the horizontalaxis are fraction numbers (0.5 mL/fraction). Absorption at 260 nmwas used to detect the four eluents; vertical scales were adjustedto equalize peak heights and enable comparison of peak widths. (B)A plot of the permeation coefficients (Kd) of nine batches of oligoclusters against the logarithm of the delaytime in seconds used in their preparation. The X axisis logarithmic.
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fig5: Hydrodynamic properties of oligoclusters prepared with differentdelay times. (A) Profiles of PBS elution from a Sephacryl S200 high-resolution10/30 column of (left to right): purified bovine IgG, 45 s delay-timeoligoclusters, bovine serum albumin, and 5 s delay-time oligoclusters. Kd, permeation coefficient; the numbers belowthe Kd’s and on the horizontalaxis are fraction numbers (0.5 mL/fraction). Absorption at 260 nmwas used to detect the four eluents; vertical scales were adjustedto equalize peak heights and enable comparison of peak widths. (B)A plot of the permeation coefficients (Kd) of nine batches of oligoclusters against the logarithm of the delaytime in seconds used in their preparation. The X axisis logarithmic.

Mentions: Thegel permeation properties of the oligoclusters prepared by the delay-timeand add-on procedures were investigated and compared to the permeationproperties of a series of purified proteins having different molecularweights and known Stokes’ radiuses (Figure 5).


Stable oligomeric clusters of gold nanoparticles: preparation, size distribution, derivatization, and physical and biological properties.

Smithies O, Lawrence M, Testen A, Horne LP, Wilder J, Altenburg M, Bleasdale B, Maeda N, Koklic T - Langmuir (2014)

Hydrodynamic properties of oligoclusters prepared with differentdelay times. (A) Profiles of PBS elution from a Sephacryl S200 high-resolution10/30 column of (left to right): purified bovine IgG, 45 s delay-timeoligoclusters, bovine serum albumin, and 5 s delay-time oligoclusters. Kd, permeation coefficient; the numbers belowthe Kd’s and on the horizontalaxis are fraction numbers (0.5 mL/fraction). Absorption at 260 nmwas used to detect the four eluents; vertical scales were adjustedto equalize peak heights and enable comparison of peak widths. (B)A plot of the permeation coefficients (Kd) of nine batches of oligoclusters against the logarithm of the delaytime in seconds used in their preparation. The X axisis logarithmic.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4230385&req=5

fig5: Hydrodynamic properties of oligoclusters prepared with differentdelay times. (A) Profiles of PBS elution from a Sephacryl S200 high-resolution10/30 column of (left to right): purified bovine IgG, 45 s delay-timeoligoclusters, bovine serum albumin, and 5 s delay-time oligoclusters. Kd, permeation coefficient; the numbers belowthe Kd’s and on the horizontalaxis are fraction numbers (0.5 mL/fraction). Absorption at 260 nmwas used to detect the four eluents; vertical scales were adjustedto equalize peak heights and enable comparison of peak widths. (B)A plot of the permeation coefficients (Kd) of nine batches of oligoclusters against the logarithm of the delaytime in seconds used in their preparation. The X axisis logarithmic.
Mentions: Thegel permeation properties of the oligoclusters prepared by the delay-timeand add-on procedures were investigated and compared to the permeationproperties of a series of purified proteins having different molecularweights and known Stokes’ radiuses (Figure 5).

Bottom Line: The crude oligocluster preparations have narrow size distributions, and for most purposes do not require fractionation.The oligoclusters do not aggregate after ∼300-fold centrifugal-filter concentration, and at this high concentration are easily derivatized with a variety of thiol-containing reagents.Unlike conventional glutathione-capped nanoparticles of comparable gold content, large oligoclusters derivatized with glutathione do not aggregate at high concentrations in phosphate-buffered saline (PBS) or in the circulation when injected into mice.

View Article: PubMed Central - PubMed

Affiliation: Department of Pathology and Laboratory Medicine, and ‡Department of Chemistry, University of North Carolina at Chapel Hill , Chapel Hill, North Carolina 27599, United States.

ABSTRACT
Reducing dilute aqueous HAuCl4 with NaSCN under alkaline conditions produces 2-3 nm diameter yellow nanoparticles without the addition of extraneous capping agents. We here describe two very simple methods for producing highly stable oligomeric grape-like clusters (oligoclusters) of these small nanoparticles. The oligoclusters have well-controlled diameters ranging from ∼5 to ∼30 nm, depending mainly on the number of subunits in the cluster. Our first ["delay-time"] method controls the size of the oligoclusters by varying from seconds to hours the delay time between making the HAuCl4 alkaline and adding the reducing agent, NaSCN. Our second ["add-on"] method controls size by using yellow nanoparticles as seeds onto which varying amounts of gold derived from "hydroxylated gold", Na(+)[Au(OH4-x)Clx](-), are added-on catalytically in the presence of NaSCN. Possible reaction mechanisms and a simple kinetic model fitting the data are discussed. The crude oligocluster preparations have narrow size distributions, and for most purposes do not require fractionation. The oligoclusters do not aggregate after ∼300-fold centrifugal-filter concentration, and at this high concentration are easily derivatized with a variety of thiol-containing reagents. This allows rare or expensive derivatizing reagents to be used economically. Unlike conventional glutathione-capped nanoparticles of comparable gold content, large oligoclusters derivatized with glutathione do not aggregate at high concentrations in phosphate-buffered saline (PBS) or in the circulation when injected into mice. Mice receiving them intravenously show no visible signs of distress. Their sizes can be made small enough to allow their excretion in the urine or large enough to prevent them from crossing capillary basement membranes. They are directly visible in electron micrographs without enhancement, and can model the biological fate of protein-like macromolecules with controlled sizes and charges. The ease of derivatizing the oligoclusters makes them potentially useful for presenting pharmacological agents to different tissues while controlling escape of the reagents from the circulation.

Show MeSH
Related in: MedlinePlus