title: Dual-Sensitized Luminescent Europium(ΙΙΙ) and Terbium(ΙΙΙ) Complexes as Bioimaging and Light-Responsive Therapeutic Agents.
abstract: Dual-photosensitized stable EuΙΙΙand TbΙΙΙcomplexes, namely [Eu(dpq)(tfnb)3] (1) and [Tb(dpq)(tfnb)3] (2), in which dpq=dipyrido[3,2-d:2',3'-f]quinoxaline and Htfnb=4,4,4-trifluoro-1-(2-napthyl)-1,3-butanedione, were designed as bioimaging and light-responsive therapeutic agents. Their X-ray structures, photophysical properties, biological interactions, photoinduced DNA damage, photocytotoxicity, and cellular uptake properties were studied. Discrete mononuclear complexes adopt an eight-coordinated {LnN2O6} distorted square antiprism geometry with bidentate N,N-donor dpq and O,O-donor tfnb ligands. The designed probes have the advantage of dual-sensitizing antennae (dpq, Htfnb) to modulate their desirable optical properties for cellular imaging and light-responsive intracellular damage. The remarkable photostability, absence of inner-sphere water (q<1), and longer excited-state lifetimes of the complexes make them suitable as cellular-imaging probes. The dpq3T state is well located energetically to allow efficient energy transfer (ET) to the emissive5D0and5D4states of EuΙΙΙand TbΙΙΙ. This leads to higher quantum yields (φ=0.15-0.20) in aqueous media and makes these compounds suitable cellular-imaging probes. The complexes display significant binding ability toward DNA and bovine serum albumin (K≈105m-1). They effectively cleave supercoiled DNA to its nicked circular form at λ=365 nm through photoredox pathways. The cellular internalization studies showed cytosolic and nuclear localization. The remarkable photocytotoxicity of these probes offers a strategy towards developing photoresponsive LnΙΙΙprobes as cellular-imaging and phototherapeutic agents.
authors: Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, Uttar Pradesh, India.
authors: Srikanth
authors: S
authors: Dasari
authors: Department of Chemical Engineering and Centre for Environmental Science and Engineering, Indian Institute of Technology Kanpur, Kanpur, 208016, Uttar Pradesh, India.
authors: Swati
authors: S
authors: Singh
authors: Department of Chemical Engineering and Centre for Environmental Science and Engineering, Indian Institute of Technology Kanpur, Kanpur, 208016, Uttar Pradesh, India.
authors: Sri
authors: S
authors: Sivakumar
authors: Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur, 208016, Uttar Pradesh, India.
authors: Ashis K
authors: AK
authors: Patra
mesh_terms: D004247:DNA / Q000737:chemistry*; D004249:DNA Damage / Q000187:drug effects*; D005063:Europium / Q000737:chemistry*; D008024:Ligands; D049449:Luminescence; D049408:Luminescent Agents / Q000737:chemistry*; D009942:Organometallic Compounds / Q000737:chemistry* / Q000627:therapeutic use*; D017319:Photosensitizing Agents / Q000737:chemistry*; D011810:Quinoxalines / Q000737:chemistry; D012710:Serum Albumin, Bovine / Q000737:chemistry*; D013725:Terbium / Q000737:chemistry*
chemical_list: D008024:Ligands; D049408:Luminescent Agents; D009942:Organometallic Compounds; D017319:Photosensitizing Agents; D011810:Quinoxalines; D013725:Terbium; D012710:Serum Albumin, Bovine; D005063:Europium; D004247:DNA
keywords: cellular imaging; europium; lanthanides; luminescence; terbium