title: Preparation of CuO/ZnO nanocomposite and its application as a cysteine/homocysteine colorimetric and fluorescence detector.
abstract: Cysteine and homocysteine play a crucial role in many biological functions but abnormal levels of these amino acids may lead to various forms of pathogenesis. Therefore, selective and easy-to-use methods for the detection of cysteine and homocysteine are essential for the early diagnosis of developing diseases. In this paper we report on a rapid, straightforward and highly selective method for the detection of cysteine (Cys) and homocysteine (Hcy) which uses a CuO/ZnO nanocomposite as a dual colorimetric and fluorometric assay. The presence of Cys and Hcy in a solution of these nanorods (NRs) induces a change in its color from light blue to dark grey which is visible to the naked eye. This is accompanied by a blue shift in the absorption spectra from 725 nm to 650 nm and a decrease in the intensity of CuO/ZnO nanocomposite emission. These changes are ascribed to the reduction of Cu(II) to Cu(0), and the oxidation of cysteine (homocysteine) and subsequent formation of the disulfide bond. This novel assay method does not respond to any other amino-acid which is present in living organisms; therefore the selective determination of cysteine (homocysteine) with a lower analyte limit of 40 μM (4.8 μg mL(-1)) can be carried out in aqueous solutions without the need for any sophisticated instrumentation, fluorophore molecules or complicated procedures.
authors.affiliation: CEITEC BUT, Brno University of Technology, Technická 10, 616 69 Brno, Czech Republic. Electronic address: michaela.simsikova@ceitec.vutbr.cz.
authors.forename: Michaela
authors.initials: M
authors.lastname: Šimšíková
authors.affiliation: CEITEC BUT, Brno University of Technology, Technická 10, 616 69 Brno, Czech Republic; Institute of Physical Engineering, Brno University of Technology, Technická 2, 616 69 Brno, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Čechal
authors.affiliation: Institute of Geotechnics, SAS, Watsonova 45, 043 53 Košice, Slovakia.
authors.forename: Anna
authors.initials: A
authors.lastname: Zorkovská
authors.affiliation: Department of Biochemistry, Faculty of Science, P.J. Šafárik University, Šrobárova 2, 041 54 Košice, Slovakia; Department of Biophysics, Institute of Experimental Physics, SAS, Watsonova 47, 040 01 Košice, Slovakia.
authors.forename: Marián
authors.initials: M
authors.lastname: Antalík
authors.affiliation: CEITEC BUT, Brno University of Technology, Technická 10, 616 69 Brno, Czech Republic; Institute of Physical Engineering, Brno University of Technology, Technická 2, 616 69 Brno, Czech Republic.
authors.forename: Tomáš
authors.initials: T
authors.lastname: Šikola
mesh_terms: D003124:Colorimetry; D003300:Copper / Q000737:chemistry*; D003545:Cysteine / Q000737:chemistry*; D005453:Fluorescence; D006710:Homocysteine / Q000737:chemistry*; D053761:Nanocomposites / Q000737:chemistry*; D015034:Zinc Oxide / Q000737:chemistry*
chemical_list: D006710:Homocysteine; D003300:Copper; D003545:Cysteine; D015034:Zinc Oxide; C030973:cupric oxide
keywords: Colorimetric sensor; CuO/ZnO nanorods; Cysteine; Fluorescence; Homocysteine; Zero-valent copper