title: Label-free colorimetric detection of biological thiols based on target-triggered inhibition of photoinduced formation of AuNPs.
abstract: A label-free colorimetric method for the detection of biological thiols (biothiols) was developed. This method is based on prevention of the photoinduced reduction of auric ions (Au(III)) in the presence of amino acids (acting as a reducing agent) by biothiols; the photoinduced reduction is inhibited due to the strong interaction of the biothiols with Au(III). In this method, the sample was first incubated in an assay solution containing Au(III) and threonine; the sample solution was then exposed to 254 nm UV light. For samples without biothiols, this process led to the photoreduction of Au(III) followed by growth of gold nanoparticles accompanied by the visually detectable development of a red coloration typified by an absorption peak at ca 530 nm. Conversely, in the presence of biothiols, reduction of Au(III) to Au(0) was prevented by entrapment of Au(III) within the biothiols via the thiol group. The solution thus remained colorless even after UV irradiation, which was used as an indicator of the presence of biothiols. Using this strategy, biothiols were very conveniently analyzed by monitoring color changes of the samples with the naked eye or a UV-vis spectrometer. The strategy based on this interesting phenomenon exhibited high selectivity toward biothiols over common amino acids and was successfully employed for reliable quantification of biothiols present in human plasma, demonstrating its great potential for clinical applications.
authors.affiliation: Department of Chemical and Biomolecular Engineering (BK21+ Program), KAIST, Daejeon 305-701, Korea. Department of Business Opportunity Analysis, Technology Innovation Analysis Center, Korea Institute of Science and Technology Information (KISTI), Seoul 130-741, Korea.
authors.forename: Ye Lim
authors.initials: YL
authors.lastname: Jung
authors.forename: Jung Hun
authors.initials: JH
authors.lastname: Park
authors.forename: Moon Il
authors.initials: MI
authors.lastname: Kim
authors.forename: Hyun Gyu
authors.initials: HG
authors.lastname: Park
mesh_terms: D015374:Biosensing Techniques / Q000379:methods*; D003124:Colorimetry / Q000379:methods*; D006046:Gold / Q000737:chemistry*; D006801:Humans; D053768:Metal Nanoparticles / Q000737:chemistry*; D013438:Sulfhydryl Compounds / Q000097:blood*
chemical_list: D013438:Sulfhydryl Compounds; D006046:Gold