title: Simple biosensor with high selectivity and sensitivity: thiol-specific biomolecular probing and intracellular imaging by AIE fluorogen on a TLC plate through a thiol-ene click mechanism.
abstract: A handy, specific, sensitive bioprobe has been developed. Tetraphenylethene (TPE) was functionalized by a maleimide (MI) group, giving a TPE-MI adduct that was nonemissive in both solution and the solid state. It was readily transformed into a fluorogen showing an aggregation-induced emission (AIE) property by the click addition of thiol to its MI pendant. The click reaction and the AIE effect enabled TPE-MI to function as a thiol-specific bioprobe in the solid state. Thus, the spot of TPE-MI on a TLC plate became emissive when it had been exposed to L-cysteine, an amino acid containing a thiol group, but remained nonemissive when exposed to other amino acids that lack free thiol units. The thiol-activated emission was rapid and strong, readily detected by the naked eye at an analyte concentration as low as approximately 1 ppb, thanks to the "lighting up" nature of the bioprobing process. Similarly, the emission of TPE-MI was turned on only by the proteins containing free thiol units, such as glutathione. Clear fluorescence images were taken when living cells were stained by using TPE-MI as a visualization agent, affording a facile fluorescent maker for mapping the distribution of thiol species in cellular systems.
authors.affiliation: Department of Chemistry, Institute of Molecular Functional Materials, The Hong Kong University of Science & Technology (HKUST), Clear Water Bay, Kowloon, Hong Kong, China.
authors.forename: Yang
authors.initials: Y
authors.lastname: Liu
authors.forename: Yong
authors.initials: Y
authors.lastname: Yu
authors.forename: Jacky W Y
authors.initials: JW
authors.lastname: Lam
authors.forename: Yuning
authors.initials: Y
authors.lastname: Hong
authors.forename: Mahtab
authors.initials: M
authors.lastname: Faisal
authors.forename: Wang Zhang
authors.initials: WZ
authors.lastname: Yuan
authors.forename: Ben Zhong
authors.initials: BZ
authors.lastname: Tang
mesh_terms: D015374:Biosensing Techniques; D002855:Chromatography, Thin Layer; D004396:Coloring Agents / Q000737:chemistry*; D003952:Diagnostic Imaging / Q000379:methods; D005030:Ethylenes / Q000737:chemistry*; D005453:Fluorescence; D008301:Maleimides / Q000737:chemistry*; D015394:Molecular Structure; D013194:Staining and Labeling / Q000379:methods; D013438:Sulfhydryl Compounds / Q000737:chemistry*
chemical_list: D004396:Coloring Agents; D005030:Ethylenes; D008301:Maleimides; D013438:Sulfhydryl Compounds; C043592:maleimide