Gold nanoparticles have an optical property that depends on the interparticle distance, and thus their aggregation can cause a noteworthy color change of the dispersion. This study investigated the aggregation of gold nanoparticles caused by various amino acids in order to develop a strategy for colorimetric detection of a biological reaction. We examined the colorimetric response of gold nanoparticles with varying concentrations of cysteine, cystine, arginine, aspartic acid, serine, and methionine solutions. The results demonstrated gradual color changes with increasing concentrations of cysteine but did not exhibit a noticeable change for other amino acids. We explored the effect of the nanoparticle size on the cysteine-induced aggregation and a smaller gold nanoparticle showed a lower detection limit than a larger one. Additionally, the sensitivity of the colorimetric response was significantly increased by adding Cu2+ to the examined dispersions due to the chelate formation between the metal ion and surface-immobilized cysteines. The overall results demonstrate that the highly sensitive aggregation of gold nanoparticles caused by cysteine in the presence of Cu2+ ion has the potential to be used for selective chemical and biological sensing for specific analytes.

Aggregation of gold nanoparticles induced by amino acids: Enhancement of colorimetric response by Cu2+

Macromolecular Chemistry: The Second Century

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ACS Spring 2020 National Meeting & Expo

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.