title: A sensitive and selective sensor for biothiols based on the turn-on fluorescence of the Fe-MIL-88 metal-organic frameworks-hydrogen peroxide system.
abstract: Herein, we present a novel strategy based on a "turn-on" fluorescence system made up of metal-organic frameworks Fe-MIL-88 and H2O2 for detecting biothiols in human serum. The nonfluorescent Fe-MIL-88 gives weak fluorescence in the presence of H2O2. Interestingly, it was found that biothiols such as glutathione (GSH), cysteine (Cys) or homocysteine (Hcy) could induce fluorescence turn-on of the Fe-MIL-88/H2O2 system. Under optimal conditions, the relative fluorescence intensity exhibited a good linear relationship in the range from 50 nM-10 μM for GSH (r = 0.994), 50 nM-10 μM for Cys (r = 0.990), and 50 nM-10 μM (r = 0.992) for Hcy; the detection limits of GSH, Cys and Hcy were 30 nM, 40 nM, and 40 nM respectively. Mechanism investigation reveals that biothiols could associate with Fe-MIL-88 via hydrogen bonding and electrostatic interaction followed by redox reaction between biothiols and Fe(3+) present in the Fe-MIL-88, Fe(3+) was thus reduced to Fe(2+), and then Fe(2+) could efficiently catalyze the decomposition of H2O2 to yield ˙OH radicals through the Fenton reaction. Besides, biothiols were able to reduce H2O2 to produce ˙OH radicals directly. Thus the Fe-MIL-88 as well as biothiols could cooperatively contribute to the activation of H2O2 to generate higher amounts of ˙OH radicals, which in turn oxidize the free ligand terephthalic acid (BDC) outside or within the Fe-MIL-88 structure to strongly fluorescent hydroxylated terephthalic acid (OHBDC), thereby turning on the fluorescence.
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China. liyf@swu.edu.cn.
authors.forename: Zheng Juan
authors.initials: ZJ
authors.lastname: Sun
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China. liyf@swu.edu.cn.
authors.forename: Jun Ze
authors.initials: JZ
authors.lastname: Jiang
authors.affiliation: Key Laboratory of Luminescent and Real-Time Analytical Chemistry (Southwest University), Ministry of Education, College of Chemistry and Chemical Engineering, Southwest University, Chongqing 400715, China. liyf@swu.edu.cn.
authors.forename: Yuan Fang
authors.initials: YF
authors.lastname: Li
mesh_terms: D000596:Amino Acids / Q000097:blood / Q000737:chemistry; D015374:Biosensing Techniques; D002623:Chemistry Techniques, Analytical / Q000379:methods*; D003545:Cysteine / Q000032:analysis / Q000097:blood / Q000737:chemistry; D005453:Fluorescence; D005978:Glutathione / Q000032:analysis / Q000097:blood / Q000737:chemistry; D006710:Homocysteine / Q000032:analysis / Q000097:blood / Q000737:chemistry; D006801:Humans; D006861:Hydrogen Peroxide / Q000737:chemistry*; D007501:Iron / Q000737:chemistry*; D057230:Limit of Detection; D008238:Lysergic Acid Diethylamide / Q000031:analogs & derivatives* / Q000737:chemistry; D009942:Organometallic Compounds / Q000032:analysis; D013438:Sulfhydryl Compounds / Q000032:analysis* / Q000097:blood; D056928:X-Ray Absorption Spectroscopy
chemical_list: D000596:Amino Acids; D009942:Organometallic Compounds; D013438:Sulfhydryl Compounds; D006710:Homocysteine; C048042:N(1)-methyl-2-lysergic acid diethylamide; D008238:Lysergic Acid Diethylamide; D006861:Hydrogen Peroxide; D007501:Iron; D005978:Glutathione; D003545:Cysteine