pH Effect on Surface Potential of Polyelectrolytes-Capped Gold Nanoparticles Probed by Surface-Enhanced Raman Scattering

Title
pH Effect on Surface Potential of Polyelectrolytes-Capped Gold Nanoparticles Probed by Surface-Enhanced Raman Scattering
Authors
이지원Kwan KimJeong-Yong ChoiKuan Soo Shin
Issue Date
2010-12
Publisher
Langmuir
Citation
VOL 26, NO 24-19169
Abstract
Nanoparticles are commonly stabilized through the adsorption of acidic/basic polyelectrolytes around the surface of the particle. One example of these nanoparticles is poly(ethylenimine) (PEI)-capped Au nanoparticles. In this work, we have examined by means of surface-enhanced Raman scattering (SERS) of 2,6-dimethylphenylisocyanide (2,6-DMPI) how much the surface potential of Au nanoparticles is affected by the solution pH through the mediation of the protonation and deprotonation of PEI in contact with Au nanoparticles. In fact, the surface-potential-dependent isocyanide (NC) stretching peak of 2,6-DMPI has shifted sharply around pH 8.5, close to the plc value of the primary amine of PEI. When a negatively charged poly(acrylic acid) (PAA) was deposited onto the PEI, the peak shift of the NC stretching band took place around pH 6.5, close to the average pK(a) value of PEI and PAA. When additional PEI was deposited on PAA, the peak shift of the NC stretching band occurred once again around pH 8.5, indicative of the stronger interaction of upper two polyelectrolyte layers. These data clearly illustrate the usefulness of SERS in the elucidation of a delicate interaction of cationic and anionic polyelectrolytes, especially in layer-by-layer deposition.
URI
http://pubs.kist.re.kr/handle/201004/72633
ISSN
0743-7463
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