Limits...
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.

Show MeSH

Related in: MedlinePlus

Urinary excretion ofsmall injected oligoclusters. Gradient gelelectrophoresis of three oligocluster preparations (P1, P2, and P3)made with delay times of 1, 2, and 5 s and derivatized with GSH. Approximately5 min after injecting the preparations intravenously into mice, urinesamples were collected from their bladders, processed as describedin the Experimental Section, and run (as U1,U2, and U3) alongside samples of the corresponding injected material.
© Copyright Policy
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC4230385&req=5

fig7: Urinary excretion ofsmall injected oligoclusters. Gradient gelelectrophoresis of three oligocluster preparations (P1, P2, and P3)made with delay times of 1, 2, and 5 s and derivatized with GSH. Approximately5 min after injecting the preparations intravenously into mice, urinesamples were collected from their bladders, processed as describedin the Experimental Section, and run (as U1,U2, and U3) alongside samples of the corresponding injected material.

Mentions: An important feature of our oligoclusters is that their sizes canbe controlled to allow or prevent their excretion by the kidney. Thiscapability is illustrated in Figure 7, whichpresents the results of experiments in which unfractionated preparationsof GSH-modified oligoclusters made with different delay times (1,2, and 5 s) were injected intravenously into mice, and their excretionin the urine was determined by comparing the gel electrophoretic behaviorof the injected and excreted materials.


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)

Urinary excretion ofsmall injected oligoclusters. Gradient gelelectrophoresis of three oligocluster preparations (P1, P2, and P3)made with delay times of 1, 2, and 5 s and derivatized with GSH. Approximately5 min after injecting the preparations intravenously into mice, urinesamples were collected from their bladders, processed as describedin the Experimental Section, and run (as U1,U2, and U3) alongside samples of the corresponding injected material.
© Copyright Policy
Related In: Results  -  Collection

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

fig7: Urinary excretion ofsmall injected oligoclusters. Gradient gelelectrophoresis of three oligocluster preparations (P1, P2, and P3)made with delay times of 1, 2, and 5 s and derivatized with GSH. Approximately5 min after injecting the preparations intravenously into mice, urinesamples were collected from their bladders, processed as describedin the Experimental Section, and run (as U1,U2, and U3) alongside samples of the corresponding injected material.
Mentions: An important feature of our oligoclusters is that their sizes canbe controlled to allow or prevent their excretion by the kidney. Thiscapability is illustrated in Figure 7, whichpresents the results of experiments in which unfractionated preparationsof GSH-modified oligoclusters made with different delay times (1,2, and 5 s) were injected intravenously into mice, and their excretionin the urine was determined by comparing the gel electrophoretic behaviorof the injected and excreted materials.

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