Luminescent ruthenium(II) polypyridine biotin complexes: synthesis, characterization, photophysical and electrochemical properties, and avidin-binding studies.
Two luminescent ruthenium(II) polypyridine complexes containing a biotin moiety [Ru(bpy)(2)(L1)](PF(6))(2) (1) and [Ru(bpy)(2)(L2)](PF(6))(2) (2) (bpy = 2,2'-bipyridine; L1 = 4-(N-((2-biotinamido)ethyl)amido)-4'-methyl-2,2'-bipyridine; L2 = 4-(N-((6-biotinamido)hexyl)amido)-4'-methyl-2,2'-bipyridine) have been synthesized and characterized, and their photophysical and electrochemical properties have been studied. Upon photoexcitation, complexes 1 and 2 display intense and long-lived triplet metal-to-ligand charge-transfer ((3)MLCT) (dpi(Ru) --> pi*(L1 or L2)) emission in fluid solutions at 298 K and in low-temperature glass. We have studied the binding of these ruthenium(II) biotin complexes to avidin by 4'-hydroxyazobenzene-2-carboxylic acid (HABA) assays, luminescence titrations, competitive assays using native biotin, and quenching experiments using methyl viologen. On the basis of the results of these experiments, a homogeneous competitive assay for biotin has been investigated.
Lo
Kenneth Kam-Wing
KK
Department of Biology and Chemistry, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong, PR China. bhkenlo@cityu.edu.hk
Lee
Terence Kwok-Ming
TK
D001360:Avidin / Q000737:chemistry* / Q000378:metabolism; D001391:Azo Compounds / Q000737:chemistry; D001710:Biotin / Q000737:chemistry* / Q000378:metabolism; D004563:Electrochemistry; D049449:Luminescence; D008958:Models, Molecular; D015394:Molecular Structure; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000737:chemistry*; D011108:Polymers / Q000737:chemistry; D011725:Pyridines / Q000737:chemistry; D012428:Ruthenium / Q000737:chemistry*
D001391:Azo Compounds; D009942:Organometallic Compounds; D011108:Polymers; D011725:Pyridines; D001360:Avidin; C001413:HABA; D001710:Biotin; D012428:Ruthenium