Journal
ANALYTICAL AND BIOANALYTICAL CHEMISTRY
Volume 395, Issue 2, Pages 489-494Publisher
SPRINGER HEIDELBERG
DOI: 10.1007/s00216-009-2982-7
Keywords
Gold nanoparticles; ssDNA; Cysteine; Colorimetric detection
Funding
- National Science Foundation [50725825]
- National Science Foundation of China [50878079]
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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 mu M. 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.
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