title: Highly sensitive detection of cysteine over glutathione and homo-cysteine: New insight into the Michael addition of mercapto group to maleimide.
abstract: A fluorescence "off-on" probe CMP for thiols was designed with coumarin as the fluorophore and maleimide as the receptor. The fluorescence of the coumarin was quenched through photoinduced electron transfer (PET) from the fluorophore to maleimide group. The Michael addition of the mercapto group toward maleimide formed a thioether with relatively weak fluorescence. The intramolecular nucleophilic substitution of amino group in cysteine (Cys) to alkylthio produced a much stronger fluorescent amino adduct, which was supported by UPLC-MS and NMR titration. The above sensing mechanism ensured CMP a highly sensitive probe toward Cys over GSH and Hcy. The fluorescence intensity at 495nm was linear with Cys concentration over the range of 0-10μM with a detection limit of 14nM and a rapid response time of 20min. High selectivity and good competition of the probe toward thiols over other biologically relevant species enabled us to monitor mercapto-containing proteins as well as fluorescence imaging Cys in living cells.
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry & Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China.
authors.forename: Zhaoyang
authors.initials: Z
authors.lastname: Chen
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry & Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China.
authors.forename: Qian
authors.initials: Q
authors.lastname: Sun
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry & Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China.
authors.forename: Yuhua
authors.initials: Y
authors.lastname: Yao
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry & Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China.
authors.forename: Xiaoxiang
authors.initials: X
authors.lastname: Fan
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry & Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China.
authors.forename: Weibing
authors.initials: W
authors.lastname: Zhang
authors.affiliation: Shanghai Key Laboratory of Functional Materials Chemistry, School of Chemistry & Molecular Engineering, East China University of Science & Technology, Shanghai 200237, China. Electronic address: junhongqian@ecust.edu.cn.
authors.forename: Junhong
authors.initials: J
authors.lastname: Qian
mesh_terms: D000818:Animals; D015374:Biosensing Techniques / Q000379:methods; D002417:Cattle; D002460:Cell Line; D003374:Coumarins / Q000737:chemistry*; D003545:Cysteine / Q000032:analysis*; D005456:Fluorescent Dyes / Q000737:chemistry*; D005978:Glutathione / Q000032:analysis*; D006710:Homocysteine / Q000032:analysis*; D057230:Limit of Detection; D008301:Maleimides / Q000737:chemistry*; D051379:Mice; D008958:Models, Molecular; D061848:Optical Imaging / Q000379:methods; D012710:Serum Albumin, Bovine / Q000737:chemistry; D013050:Spectrometry, Fluorescence / Q000379:methods; D013438:Sulfhydryl Compounds / Q000032:analysis
chemical_list: D003374:Coumarins; D005456:Fluorescent Dyes; D008301:Maleimides; D013438:Sulfhydryl Compounds; D006710:Homocysteine; C043592:maleimide; D012710:Serum Albumin, Bovine; C030123:coumarin; D005978:Glutathione; D003545:Cysteine
keywords: Bio-imaging application; Cysteine detection; Fluorescent probe; Maleimide; Sensing mechanism