We present a fluorescence-based assay for the characterization of functionalized gold nanoparticles (AuNPs) capped with a self-assembled monolayer of mixed thiols derived from poly(ethylene glycol) (PEG). These water-soluble AuNPs carry primary amino groups at the solvent-exposed interface, which can be used for further conjugation of biologically active molecules. The reported assay allows quantification of the average number of functionalizable amino groups per particle (N-NH2) with a relative uncertainty below or equal to +/- 14% (95% confidence interval), thus providing essential information for the successive derivatization of the AuNPs. Here, a fluorescently labeled derivative of peptide-neurotoxin conantokin-G was coupled to the amino groups of the particle ligand shell via a flexible linker, We quantitatively determined the average number of peptides per particle (N-pept) and the yield of the two-step conjugation strategy. AuNPs carrying 50-70 copies of the peptide were obtained. In addition, we have gained insights into the deterioration of the self-assembled monolayer due to thiol desorption with time. Under ordinary storage conditions in solution and at room temperature, a decrease in N-NH2 between 48% and 75% could be observed at the end of the period of investigation (42-56 days). Slow desorption of the conjugated peptides upon storage was also observed and quantified (similar to 25% in 14 days).

Quantification and Reactivity of Functional Groups in the Ligand Shell of PEGylated Gold Nanoparticles via a Fluorescence-Based Assay

Fiammengo, R.
2009-01-01

Abstract

We present a fluorescence-based assay for the characterization of functionalized gold nanoparticles (AuNPs) capped with a self-assembled monolayer of mixed thiols derived from poly(ethylene glycol) (PEG). These water-soluble AuNPs carry primary amino groups at the solvent-exposed interface, which can be used for further conjugation of biologically active molecules. The reported assay allows quantification of the average number of functionalizable amino groups per particle (N-NH2) with a relative uncertainty below or equal to +/- 14% (95% confidence interval), thus providing essential information for the successive derivatization of the AuNPs. Here, a fluorescently labeled derivative of peptide-neurotoxin conantokin-G was coupled to the amino groups of the particle ligand shell via a flexible linker, We quantitatively determined the average number of peptides per particle (N-pept) and the yield of the two-step conjugation strategy. AuNPs carrying 50-70 copies of the peptide were obtained. In addition, we have gained insights into the deterioration of the self-assembled monolayer due to thiol desorption with time. Under ordinary storage conditions in solution and at room temperature, a decrease in N-NH2 between 48% and 75% could be observed at the end of the period of investigation (42-56 days). Slow desorption of the conjugated peptides upon storage was also observed and quantified (similar to 25% in 14 days).
2009
Gold
Metal Nanoparticles
Models, Theoretical
Molecular Structure
Polyethylene Glycols
Fluorescence
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/11562/1025859
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