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HemoCD as an Artificial Oxygen Carrier: Oxygen Binding and Autoxidation
Author(s) -
Kano Koji,
Kitagishi Hiroaki
Publication year - 2009
Publication title -
artificial organs
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.684
H-Index - 76
eISSN - 1525-1594
pISSN - 0160-564X
DOI - 10.1111/j.1525-1594.2008.00704.x
Subject(s) - autoxidation , oxygen , chemistry , organic chemistry
Despite many attempts to construct completely artificial systems for carrying oxygen (O 2 ) in aqueous solution, no successful example had been reported until quite recently except for picket fence porphinatoiron(II) embedded in liposomal membrane. We newly prepared a 1:1 complex (hemoCD) of 5,10,15,20‐tetrakis(4‐sulfonatophenyl)porphinatoiron(II) (Fe[II]TPPS) and a per‐ O ‐methylated β‐cyclodextrin dimer having a pyridine linker (Py3CD). HemoCD binds O 2 reversibly in aqueous solution. The oxygen affinity corresponding to the partial O 2 pressure, at which half of the hemoCD molecules are oxygenated, was 16.9 torr in phosphate buffer at pH 7.0 and 25°C. Oxy‐hemoCD was gradually autoxidized ( t 1/2 = 30.1 h) due to nucleophilic attack of a water molecule to the O 2 –Fe bond. Encapsulation of the iron center of Fe(II)TPPS by two cyclodextrin truncated cones is essential for binding of O 2 to the ferrous center of the porphyrin. This manuscript reports the basic characteristics of hemoCD and the possible future utility of a totally artificial O 2 carrier.