title: Simple and sensitive colorimetric detection of cysteine based on ssDNA-stabilized gold nanoparticles.
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 microM. 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.
authors.affiliation: State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan University, Changsha, 410082, China.
authors.forename: Zhang
authors.initials: Z
authors.lastname: Chen
authors.forename: Shenglian
authors.initials: S
authors.lastname: Luo
authors.forename: Chengbin
authors.initials: C
authors.lastname: Liu
authors.forename: Qingyun
authors.initials: Q
authors.lastname: Cai
mesh_terms: D015374:Biosensing Techniques / Q000191:economics / Q000379:methods*; D003545:Cysteine / Q000032:analysis*; D004277:DNA, Single-Stranded / Q000737:chemistry*; D006046:Gold / Q000737:chemistry*; D053768:Metal Nanoparticles / Q000737:chemistry*; D012680:Sensitivity and Specificity; D013053:Spectrophotometry / Q000191:economics / Q000379:methods
chemical_list: D004277:DNA, Single-Stranded; D006046:Gold; D003545:Cysteine