title: Detection of mercury ion by infrared fluorescent protein and its hydrogel-based paper assay.
abstract: Mercury is a highly hazardous and widespread pollutant with bioaccumulative properties. Novel approaches that meet the criteria of desired selectivity, high sensitivity, good biocompatibility, and low background interference in natural settings are continuously being explored. We herein describe a new strategy utilizing the combination of infrared fluorescent protein (IFP) and its chromophore as an infrared fluorescence probe for mercury ion (Hg(II)) detection. Hg(II) has been validated to have specific binding affinity to a cysteine residue (C24) of IFP, thereby inhibiting the conjugation of IFP chromophore biliverdin (BV) to C24 and "turning off" the infrared emission of IFP. The IFP/BV sensor has high selectivity toward Hg(II) among other metal ions over a broad pH range. The in vitro detection limit was determined to be less than 50 nM. As a genetically encoded probe, we demonstrate the IFP/BV sensor can serve as a tool to detect Hg(II) in living organisms or tissues. Moreover, we have exploited a protein-agarose hydrogel-based paper assay to immobilize IFP for detection of Hg(II) in a portable and robust fashion.
authors.affiliation: Department of Chemical and Biomolecular Engineering, University of California, Los Angeles, Los Angeles, California 90095, United States. guzhen@mit.edu
authors.forename: Zhen
authors.initials: Z
authors.lastname: Gu
authors.forename: Muxun
authors.initials: M
authors.lastname: Zhao
authors.forename: Yuewei
authors.initials: Y
authors.lastname: Sheng
authors.forename: Laurent A
authors.initials: LA
authors.lastname: Bentolila
authors.forename: Yi
authors.initials: Y
authors.lastname: Tang
mesh_terms: D001664:Biliverdine / Q000378:metabolism; D001667:Binding, Competitive; D015374:Biosensing Techniques / Q000295:instrumentation*; D003545:Cysteine / Q000378:metabolism; D057809:HEK293 Cells; D006801:Humans; D020100:Hydrogels / Q000737:chemistry* / Q000378:metabolism*; D008164:Luminescent Proteins / Q000737:chemistry* / Q000378:metabolism*; D008628:Mercury / Q000032:analysis* / Q000378:metabolism; D008958:Models, Molecular; D010209:Paper; D011487:Protein Conformation; D015203:Reproducibility of Results; D013055:Spectrophotometry, Infrared
chemical_list: D020100:Hydrogels; D008164:Luminescent Proteins; D008628:Mercury; D003545:Cysteine; D001664:Biliverdine