Immobilization of Dinuclear Complexes in Mesoporous Silica Nanoparticle Mimicking the Superoxide Dismutases Activity
Date Issued
2012
Date
2012
Author(s)
Lu, Bo-Cyuan
Abstract
Binuclear imidazolate-bridged copper(Ⅱ) complexes have attracted much attention as models for mimicking superoxide dismutase (SOD). SOD is a class of enzymes that can catalyze the dismutation of excess superoxide radical (O2-•) into oxygen (O2) and hydrogen peroxide (H2O2) in organisms.
Dismutation reaction:
M(n+1)+-SOD + O2-• → M(n+)-SOD + O2 (1)
Mn+-SOD + O2-• + 2H+ → M(n+1)+-SOD + H2O2 (2)
A series of homo- and hetero- dinuclear imidazolate-bridged complexes, [(Bipy)2Cu-Im-Cu(Bipy)2](ClO4)3．CH3OH, [(Bipy)2Cu-Im-Zn(Bipy)2](ClO4)3．CH3OH, [(Bipy)2Cu-E-Im-Cu(Bipy)2](BF4)3, [(Bipy)2Cu-E-Im-Zn(Bipy)2](BF4)3 (Bipy = 2,2''-Bipyridyl, E-Im = 2-ethylimidazole), were synthesized.
The mimic complexes were characterized by elemental analysis (EA), ICP-MS, UV-VIS and EPR. The SOD-like activities were determined via decay of superoxide ions (O2-•) by a NBT (NitroBlue Tetrazolium) assay. These complexes catalyzed the dismutation of superoxide radical (O2-•) at biological pH.
Finally, we immobilized these complexes in mesoporous silica nanoparticles (MSN) as a possible model for native CuZnSOD enzyme. We also prepared Al-MSN and Al-MSN-N+ to compare the activities and confirm our hypothesis. The MSN solids mimic the protein framework of CuZnSOD which plays a role as skeleton protection here. Spectroscopic studies further allowed us to establish the structure reactivity relationship between the nanostructure of MSN and efficacy of SOD-like of MSN, Al-MSN and Al-MSN-N+.
Subjects
Superoxide dismutase
mesoporous silica
dinuclear imidazolate-bridged
mimic enzyme
Type
thesis
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