title: Two-photon ratiometric fluorescent sensor based on specific biomolecular recognition for selective and sensitive detection of copper ions in live cells.
abstract: In this work, we develop a ratiometric two-photon fluorescent probe, ATD@QD-E2Zn2SOD (ATD = amino triphenylamine dendron, QD = CdSe/ZnSe quantum dot, E2Zn2SOD = Cu-free derivative of bovine liver copper-zinc superoxide dismutase), for imaging and sensing the changes of intracellular Cu(2+) level with clear red-to-yellow color change based on specific biomolecular recognition of E2Zn2SOD for Cu(2+) ion. The inorganic-organic nanohybrided fluorescent probe features two independent emission peaks located at 515 nm for ATD and 650 nm for QDs, respectively, under two-photon excitation at 800 nm. Upon addition of Cu(2+) ions, the red fluorescence of QDs drastically quenches, while the green emission from ATD stays constant and serves as a reference signal, thus resulting in the ratiometric detection of Cu(2+) with high accuracy by two-photon microscopy (TPM). The present probe shows high sensivity, broad linear range (10(-7)-10(-3) M), low detection limit down to ∼10 nM, and excellent selectivity over other metal ions, amino acids, and other biological species. Meanwhile, a QD-based inorganic-organic probe demonstrates long-term photostability, good cell-permeability, and low cytotoxicity. As a result, the present probe can visualize Cu(2+) changes in live cells by TPM. To the best of our knowledge, this is the first report for the development of a QD-based two-photon ratiometric fluorescence probe suitable for detection of Cu(2+) in live cells.
authors.affiliation: Department of Chemistry, Tongji University , Siping Road 1239, Shanghai 200092, P. R. China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Fu
authors.forename: Changqin
authors.initials: C
authors.lastname: Ding
authors.forename: Anwei
authors.initials: A
authors.lastname: Zhu
authors.forename: Zifeng
authors.initials: Z
authors.lastname: Deng
authors.forename: Yang
authors.initials: Y
authors.lastname: Tian
authors.forename: Ming
authors.initials: M
authors.lastname: Jin
mesh_terms: D000588:Amines / Q000737:chemistry; D000818:Animals; D015374:Biosensing Techniques / Q000379:methods*; D002417:Cattle; D002470:Cell Survival; D003300:Copper / Q000378:metabolism*; D005456:Fluorescent Dyes / Q000737:chemistry; D006367:HeLa Cells; D006801:Humans; D036641:Microscopy, Fluorescence, Multiphoton / Q000379:methods*; D045663:Quantum Dots; D013482:Superoxide Dismutase / Q000737:chemistry / Q000378:metabolism
chemical_list: D000588:Amines; D005456:Fluorescent Dyes; D003300:Copper; D013482:Superoxide Dismutase