Electrochemical Estimations of the Gold Nanoparticle Size Effect on Cysteine-Gold Oxidation

Elena Romanovskaia,Lila Laundry-Mottiar,Valentin Romanovski,Michael Auinger,Maroš Halama,Peter Slovenský,Yolanda S Hedberg,S Marzieh Kalantarian

doi:10.1149/1945-7111/ac4bf8

Elena Romanovskaia, Lila Laundry-Mottiar + Show 6 more

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Gold nanoparticles are interesting for nanobiomedical applications, such as for drug delivery and as diagnostic imaging contrast agents. However, their stability and reactivity in-vivo are influenced by their surface properties and size. Here, we investigate the electrochemical oxidation of differently sized citrate-coated gold nanoparticles in the presence and absence of L-cysteine, a thiol-containing amino acid with high binding affinity to gold. We found that smaller sized (5, 10 nm) gold nanoparticles were significantly more susceptible to electrochemical L-cysteine interactions and/or L-cysteine-facilitated gold oxidation than larger (20, 50 nm) sized gold nanoparticles, both for the same mass and nominal surface area, under the conditions investigated (pH 7.4, room temperature, stagnant solutions, and scan rates of 0.5 to 450 mV s−1). The electrochemical measurements of drop-casted gold nanoparticle suspensions on paraffin-impregnated graphite electrodes were susceptible to the quality of the electrode. Increased cycling resulted in irreversible oxidation and detachment/oxidation of gold into solution. Our results suggest that L-cysteine-gold interactions are stronger for smaller nanoparticles.

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Electrochemical Estimations of the Gold Nanoparticle Size Effect on Cysteine-Gold Oxidation, E
The 10 nm Au NPs deviated most from their nominal size, while the 5, 20, and 50 nm Au NPs suspensions complied within 10% of their nominal value (Fig. 1b)
Cyclic voltammetry of differently sized Au NPs immobilized on paraffin-impregnated graphite electrode (PIGE).—it was evaluated whether L-cysteine was a good model amino acid to investigate biomolecule-involved Au oxidation/ dissolution processes of relevance for in-vitro and in-vivo conditions

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Electrochemical Estimations of the Gold Nanoparticle Size Effect on Cysteine-Gold Oxidation, E. To cite this article: Elena Romanovskaia et al 2022 J. Gold (Au) nanoparticles (NPs) have been considered for a wide range of biomedical applications, following intravenous injection, because of their high density, relatively high chemical stability, and the possibility to attach agents such as tumor-targeting agents.[1,2] The in-vivo environment, with its high ionic strength, high complexation capacity, and sometimes very oxidative environments is able to dissolve Au under certain conditions. Cyclic voltammetry (CV) in the same study[9] revealed a stronger oxidation peak for the 5 nm Au NPs than for 50 nm Au NPs (for the same mass) and for higher L-cysteine. The aim of this study is to experimentally investigate any NP size effect for citrate-coated Au NPs, ranging from 5 to 50 nm in diameter, on their Au and/or amino acid oxidation peaks using CV. To be able to understand and interpret our data, we conducted these measurements in different control solutions, for equal mass and equal nominal surface area of NPs, for different scan rates and cycle numbers, and for different electrodes and potentiostats

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