High selective and sensitive detection of Zn(II) using tetrapeptide-based dansyl fluorescent chemosensor and its application in cell imaging.

The zinc ions (Zn) play extremely irreplaceable role in the organism and the environment, the design and synthesis of a biomolecule-based fluorescence chemosensor for the detection of Zn with high sensitivity is very important. Herein, a novel tetrapeptide-based dansyl fluorescent "turn-on" response chemosensor (L) has been designed and synthesized by solid phase peptide synthesis (SPPS). As designed, L can detect Zn ions with specifically and sensitively based on photo-induced electron transfer (PET) mechanism in 100% aqueous solutions, and other metal ions do not interfere with Zn ions recognition. The stoichiometric ratio of L with Zn ions was 2:1, which matches with fluorescence titration and Job-plot assay. In addition, the reversibility and circularly process of the detection of L was confirmed by adding bonding agent NaEDTA. Moreover, L exhibits excellent biocompatibility and low biotoxicity with the limit of detection (LOD) for Zn about 18 nM, and has been successfully utilized for fluorescence imaging of Zn ions in living HeLa cells under physiological conditions.