Simple and sensitive colorimetric detection of cysteine based on ssDNA-stabilized gold nanoparticles |
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Authors: | Zhang Chen Shenglian Luo Chengbin Liu and Qingyun Cai |
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Institution: | (1) State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China;(2) School of Environment and Chemical Engineering, Nanchang Hangkong University, Nanchang, 330063, China |
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Abstract: | In this paper, we demonstrate a simple and sensitive colorimetric detection of cysteine based on the cysteine-mediated color
change of ssDNA-stabilized gold nanoparticles (AuNPs). Cysteine is capable of absorbing onto AuNPs surfaces via the strong
interaction between its thiol group and gold. ssDNA molecules which stabilize AuNPs against salt-induced aggregation are removed
away by cysteine encapsulation on the AuNPs surfaces, resulting in a characteristic color change of AuNPs from red to blue
as soon as salt is added. The ratio of absorptions at 640 to 525 nm (A
640/A
525) is linear dependent on the cysteine concentration in the range from 0.1 to 5 μM. Furthermore, amino acids other than cysteine
cannot mediate the color change under the identical conditions due to the absence of thiol groups, suggesting the selectivity
of the proposed method toward cysteine. The employment of complicated protocols and sophisticated processes such as the preparation
of modified AuNPs are successfully avoided in design to realize the simple and low-cost cysteine detection; and the high sensitivity
and low cost of the method is favorable for practical applications.
Figure In the presence of cysteine, cysteine binds to the AuNPs surface via Au-S bond, spontaneously driving ssDNA molecules away
from the nanoparticles, which leads to the AuNPs aggregation under the condition of NaCl introduction, and the corresponding
color change from red to blue. However, the presence of other amino acids results in no color change due to the absence of
thiol groups.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. |
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Keywords: | Gold nanoparticles ssDNA Cysteine Colorimetric detection |
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