title: A one-step selective fluorescence turn-on detection of cysteine and homocysteine based on a facile CdTe/CdS quantum dots-phenanthroline system.
abstract: In this paper, we report a simple, selective, sensitive and low-cost turn-on photoluminescent sensor for cysteine and homocysteine based on the fluorescence recovery of the CdTe/CdS quantum dots (QDs)-phenanthroline (Phen) system. In the presence of Phen, the fluorescence of QDs could be quenched effectively due to the formation of the non-fluorescent complexes between water-soluble thioglycolic acid (TGA)-capped QDs and Phen. Subsequently, upon addition of cysteine and homocysteine, the strong affinity of cysteine and homocysteine to QDs enables Phen to be dissociated from the surface of QDs and to form stable and luminescent complexes with cysteine and homocysteine in solution. Thus, the fluorescence of CdTe/CdS QDs was recovered gradually. A good linear relationship was obtained from 1.0 to 70.0 μM for cysteine and from 1.0 to 90.0 μM for homocysteine, respectively. The detection limits of cysteine and homocysteine were 0.78 and 0.67 μM, respectively. In addition, the method exhibited a high selectivity for cysteine and homocysteine over the other substances, such as amino acids, thiols, proteins, carbohydrates, etc. More importantly, the sensing system can not only achieve quantitative detection of cysteine and homocysteine but also could be applied in semiquantitative cysteine and homocysteine determination by digital visualization. Therefore, as a proof-of-concept, the proposed method has potential application for the selective detection of cysteine and homocysteine in biological fluids.
authors.affiliation: Key Laboratory for the Chemistry and Molecular Engineering of Medicinal Resources (Ministry of Education of China), College of Chemistry and Chemical Engineering of Guangxi Normal University, Guilin 541004, China.
authors.forename: Sheng
authors.initials: S
authors.lastname: Chen
authors.forename: Jianniao
authors.initials: J
authors.lastname: Tian
authors.forename: Yixuan
authors.initials: Y
authors.lastname: Jiang
authors.forename: Yanchun
authors.initials: Y
authors.lastname: Zhao
authors.forename: Juanni
authors.initials: J
authors.lastname: Zhang
authors.forename: Shulin
authors.initials: S
authors.lastname: Zhao
mesh_terms: D001826:Body Fluids / Q000737:chemistry; D019187:Cadmium Compounds / Q000737:chemistry*; D003545:Cysteine / Q000097:blood*; D006710:Homocysteine / Q000097:blood*; D006801:Humans; D010618:Phenanthrolines / Q000737:chemistry*; D045663:Quantum Dots; D013050:Spectrometry, Fluorescence / Q000379:methods; D013431:Sulfates / Q000737:chemistry*; D013691:Tellurium / Q000737:chemistry*
chemical_list: D019187:Cadmium Compounds; D010618:Phenanthrolines; D013431:Sulfates; D006710:Homocysteine; C037123:cadmium sulfate; D003545:Cysteine; D013691:Tellurium; C028337:cadmium telluride
keywords: Cysteine and homocysteine; Detection; Phenanthroline; Quantum dots