title: Novel Fluorometric Assay for Detection of Cysteine as a Reducing Agent and Template in Formation of Copper Nanoclusters.
abstract: This study was designed to develop a highly selective and sensitive method towards fluorimetric sensing of cysteine (Cys) in water and human serum by using copper nanocluster. The Cys-CuNCs were characterized by scanning electron microscopy (SEM), FTIR, fluorescence and UV-Vis analysis. Spectroscopic evidences showed different intensities that were attributed to the different size of Cys-CuNCs. Enhancement in fluorescence intensity of copper nanoclusters with an increase in concentration of cysteine may enable them to be good candidates in detection systems. Selective recognition of cysteine in aqueous and serum samples was achieved during the formation of various copper nanoclusters (Cys-CuNCs) with different size. Under the optimized conditions, two linear range of the nanobiosensor for cysteine were between the 5 μM to 50 μM with detection limit of 2.4 μM and between 60 μM to 500 μM with detection limit of 55 μM. Fluorescence intensity increased with addition of cysteine concentration from 5 to 50 μM. The proposed low-cost nanobiosensor exhibited high reproducibility and good selectivity. It has been used also for the determination of cysteine in human serum samples with recoveries of 97-103 % and RSDs of 1.8-3.6.
authors.affiliation: Department of Life Science Engineering, Faculty of New Sciences & Technologies, University of Tehran, Tehran, Iran.
authors.forename: Yasaman-Sadat
authors.initials: YS
authors.lastname: Borghei
authors.affiliation: Department of Life Science Engineering, Faculty of New Sciences & Technologies, University of Tehran, Tehran, Iran. smhosseini@khayam.ut.ac.ir.|Medical Biomaterials Research Center, Tehran University of Medical Sciences, Tehran, Iran. smhosseini@khayam.ut.ac.ir.
authors.forename: Morteza
authors.initials: M
authors.lastname: Hosseini
authors.affiliation: Department of Pharmaceutical Biomaterials and Medical Biomaterials Research Center, Faculty of Pharmacy, Tehran University of Medical Sciences, Tehran, Iran.|Department of Medicinal Chemistry, Faculty of Pharmacy and Pharmaceutical Sciences, Research Center, Tehran University of Medical Sciences, Terhan, 14176, Iran.
authors.forename: Mehdi
authors.initials: M
authors.lastname: Khoobi
authors.affiliation: Center of Excellence in Electrochemistry, Faculty of Chemistry, University of Tehran, Tehran, Iran.|Biosensor Research Center, Endocrinology & Metabolism Molecular-Cellular Sciences Institute, Tehran University of Medical Sciences, Tehran, Iran.
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Ganjali
keywords: Copper nanocluster; Cysteine; Enhancement; Fluorescence; Human serum; Nanobiosensor