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Modification of Luminescent Iridium(III) Polypyridine Complexes with Discrete Poly(ethylene glycol) (PEG) Pendants: Synthesis, Emissive Behavior, Intracellular Uptake, and PEGylation Properties
Author(s) -
Li Steve PoYam,
Liu HuaWei,
Zhang Kenneth Yin,
Lo Kenneth KamWing
Publication year - 2010
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.201000474
Subject(s) - pegylation , ethylene glycol , chemistry , peg ratio , polymer chemistry , nuclear chemistry , polyethylene glycol , luminescence , organic chemistry , materials science , optoelectronics , finance , economics
We report the synthesis, characterization, and photophysical properties of a new class of luminescent cyclometalated iridium(III) polypyridine poly(ethylene glycol) (PEG) complexes [Ir(N^C) 2 (N^N)](PF 6 ) (HN^C=Hppy (2‐phenylpyridine), N^N=bpyCONHPEG1 (bpy=2,2′‐bipyridine; 1 a ), bpyCONHPEG3 ( 1 b ); HN^C=Hpq (2‐phenylquinoline), N^N=bpyCONHPEG1 ( 2 a ), bpyCONHPEG3 ( 2 b ); HN^C=Hpba (4‐(2‐pyridyl)benzaldehyde), N^N=bpyCONHPEG1 ( 3 )) and their PEG‐free counterparts (N^N=bpyCONHEt, HN^C=Hppy ( 1 c ); HN^C=Hpq ( 2 c )). The cytotoxicity and cellular uptake of these complexes have been investigated by the MTT assay, ICPMS, laser‐scanning confocal microscopy, and flow cytometry. The results showed that the complexes supported by the water‐soluble PEG can act as biological probes and labels with considerably reduced cytotoxicity. Because the aldehyde groups of complex 3 are reactive toward primary amines, the complex has been utilized as the first luminescent PEGylation reagent. Bovine serum albumin (BSA) and poly(ethyleneimine) (PEI) have been PEGylated with this complex, and the resulting conjugates have been isolated, purified, and their photophysical properties studied. The DNA‐binding and gene‐delivery properties of the luminescent PEI conjugate 3 ‐PEI have also been investigated.