Dual-Sensitized Luminescent Europium(ΙΙΙ) and Terbium(ΙΙΙ) Complexes as Bioimaging and Light-Responsive Therapeutic Agents

详细信息    查看全文

• 作者：Srikanth Dasari ; Swati Singh ; Prof. Dr. Sri Sivakumar and Prof. Dr. Ashis K. Patra
• 刊名：Chemistry - A European Journal
• 出版年：2016
• 出版时间：November 21, 2016
• 年：2016
• 卷：22
• 期：48
• 页码：17387-17396
• 全文大小：4576K
• ISSN：1521-3765

文摘

Dual-photosensitized stable Eu^ΙΙΙ and Tb^ΙΙΙ complexes, namely [Eu(dpq)(tfnb)b>3b>] (<b>1b>) and [Tb(dpq)(tfnb)b>3b>] (<b>2b>), 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 {LnNb>2b>Ob>6b>} 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 dpq ³T state is well located energetically to allow efficient energy transfer (ET) to the emissive ⁵Db>0b> and ⁵Db>4b> states of Eu^ΙΙΙ and Tb^ΙΙΙ. 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≈10⁵ m⁻¹). They effectively cleave supercoiled DNA to its nicked circular form at &lambda;=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 Ln^ΙΙΙ probes as cellular-imaging and phototherapeutic agents.