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Sodium hydroxide as pretreatment and fluorosurfactant-capped gold nanoparticles as sensor for the highly selective detection of cysteine

Wu, Hsin-Pin and Huang, Chia-Chi and Cheng, Tian-Lu and Tseng, Wei-Lung (2008) Sodium hydroxide as pretreatment and fluorosurfactant-capped gold nanoparticles as sensor for the highly selective detection of cysteine. TALANTA, 76 (2). pp. 347-352.

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Official URL: http://www.sciencedirect.com/science?_ob=ArticleUR...

Abstract

A sensor for detecting cysteine (Cys) in a solution of fluorosurfactant (FSN)-capped gold nanoparticles (AuNPs) has been developed. Under acidic conditions, FSN-capped AuNPs are aggregated in the presence of homocysteine (HCys) and Cys but not in the presence of cysteinylglycine, glutathione, and gamma-glutamycysteine. When adding NaOH to a solution of HCys, the five-membered ring transition state is formed through intramolecular hydrogen abstraction. By contrast, it is difficult for Cys to form a four-membered ring transition state after Cys has been pretreated with NaOH. As a result, the HCys-induced aggregation of the FSN-capped AuNPs is suppressed because the five-membered ring transition state exhibits relatively larger steric hindrance and has stronger interaction with the FSN molecules. Thus, we can discriminate between Cys and HCys on the basis of different aggregation kinetics. Under the optimum condition, the selectivity of the probe for Cys in aqueous solutions is remarkably high over the other aminthiols. Note that HCys and Cys have very similar structure and pK(a) value. We have validated the applicability of our method through the analyses of Cys in urine samples. It is believed that this approach has great potential for the detection of Cys in biological samples. (C) 2008 Elsevier B.V. All rights reserved.

Item Type:Article
Uncontrolled Keywords:homocysteine; cysteine; gold nanoparticles; fluorosurfactant
Subjects:Analytical Science > Nanotechnology for sensing and actuating
ID Code:731
Deposited By:SPI
Deposited On:21 Jan 2009 11:51
Last Modified:21 Jan 2009 11:51

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