Paper AS+BI+EM+NL+NS+SS-ThM10
Monitoring the Citric Acid Content on Dialyzed Gold Nanoparticle
Thursday, October 31, 2013, 11:00 am, Room 204
| Session: |
Nanoparticle Surface Chemistry |
| Presenter: |
G. Ceccone, EC-JRC-IHCP, Italy |
| Authors: |
V. Spampinato, EC-JRC-IHCP, Italy
R. La Spina, EC-JRC-IHCP, Italy
D. Gilliland, EC-JRC-IHCP, Italy
L. Calzolai, EC-JRC-IHCP, Italy
G. Ceccone, EC-JRC-IHCP, Italy
F. Rossi, EC-JRC-IHCP, Italy
|
| Correspondent: |
Click to Email |
Gold nanoparticles (GNPs) are probably the most investigated metal nanomaterials due to their interesting properties. In fact, GNPs are applied in a several areas including material sciences, catalysis and biomedical diagnostics[1] Most of the applications of GNPs in the medical and biosensing fields require the development of careful purification to obtain afterwards a more efficient surface functionalization.[3,4] The process of purification is usually obtained by filtration, centrifugation and/or dialysis of the GNPs solution to remove part of the citrate or other stabilizing agents.[5,6] The citrate reduction Au(III) in water, known as Turkevich method, is one of the most used synthesis process to produce monodispersed and stable GNPs. [8] In this synthesis, the citrate is either the reducing agent and the stabilizer and it is used in large excess in comparison to the amount of gold.[9] In this work, we have investigated the stability and effect of dialysis on citrate stabilized GNPs by quantifying the content of citrate by Nuclear Magnetic Resonance (1H-NMR), and by characterizing the GNPs/citrate interface chemistry using X-ray Photoelectron Spectroscopy (XPS) and Time of Flight Secondary Ion Mass Spectrometry (ToF-SIMS). In these studies, 15 nm gold nanoparticles stabilized with the citrate have been synthesized via the Turkevich process and the content of citrate was monitored at several or different cycles of dialysis against ultrapure water. These systematic studies showed a decreasing of the citrate content with the dialysis cycles. In particular, XPS and ToF-SIMS show that for low dialysis cycles the ratio Au/Na and Au/CHO increase almost linearly, while after 9 dialysis cycles a plateau is reached. A Similar trend is observed by1H-NMR where the amount of citrate is quantified against an internal standard. The behavior of the GNPs at different dialysis cycles was also monitored by Centrifuge Particle Separation (CPS) and Dynamic Light Scattering (DLS) and UV-Vis spectra, revealing that several dialysis cycle result in a partial aggregation of the nanoparticles.
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[7] C. Chen, et al.Nano Lett., 2006, 6 (4), pp 611–615
[8] J. Turkevich, et al., Discuss. Faraday Soc., 1951, 11, 55
[9] M. Doyen, et al, J. Coll. Int. Sci., 2013, 399, 1