Preparation, characterization and activity of CuZn and Cu2 superoxide dismutase mimics encapsulated in mesoporous silica

Abstract

Encapsulation of three superoxide dismutase (SOD) functional mimics, [CuZn(dien)2(μ-Im)(ClO4)2]ClO4 (1), [Cu2(dien)2(μ-Im)(ClO4)2]ClO4 (2) (Im = imidazolate, dien = diethylenetriamine), and [CuZn(salpn)Cl2] (3) (H2salpn = 1,3bis(salicylideneamino)propane) in mesoporous MCM-41 silica afforded three hybrid catalysts 1@MCM-41, 2@MCM-41 and 3@MCM-41. Spectroscopic and magnetic analyses of these materials confirmed the metal centers of the complexes keep the coordination sphere after insertion into the MCM-41 silica matrix. For the imidazolatebridged complexes the silica channels restraint the relative orientation of the two metal ions. While 3@MCM-41 shows SOD activity significantly lower than the host-free complex, insertion of the imidazolate-bridged CuZn or Cu2 complexes by ion exchange onto mesoporous MCM-41 silica affords durable and recoverable supported catalysts with much better SOD activity than the free complexes. For confined imidazolate-bridged complexes, 1@MCM-41 and 2@MCM-41, the small pore size of the silica matrix improves the SOD activity more than a host with larger pores. This high SOD activity is attributed to the close-fitting of the complexes into the nanochannels of MCM-41 silica that favors the Cu active site and HImZn(or Cu) group stay in close proximity during catalysis.

Superoxide dismutase nanozymes: an emerging star for anti-oxidation

“…This result was demonstrated by encapsulation with two different silica structures. 1,127 Another experiment combined different metal active center complexes into boehmite nanoparticles (BNPs). It was found that binuclear Cu 2+ complexes showed a significant increase in SOD-like activity.…”

Exploring the effect of pore size on the activity of superoxide dismutase mimics immobilized in mesoporous spherical silica particles

“…[8][9][10] Among the solid supports, mesoporous silica particles (MSP) possess a large contact surface and pore volume which allow high catalyst loading, 11,12 chemical and mechanical stability, 13,14 biocompatibility 15 and controllable geometric parameters that enable a suitable design of different types and sizes of pores. 11 In previous works we have reported that encapsulation in MSPs improves the SOD activity of imidazolato-bridged CuZn-and CuCu-mimics, 16,17 and that the SOD activity doubled as the pore size of MSP reduced from 8.6 to 3.4 nm. Aimed at verifying if a closer fitting of the silica channels size to the catalyst dimension can be used to further enhance the SOD activity of these complexes, in this work we prepared mesoporous spherical silica particles (MSSP) with pore diameter smaller than the previous ones, and evaluated the SOD activity of [Cu 2 (dien) 2 (m-Im)(ClO 4 ) 2 ]ClO 4 (1) (Im = imidazolate, dien = diethylenetriamine), shown in Fig.…”

Improvement in the Pharmacological Profile of Copper Biological Active Complexes by Their Incorporation into Organic or Inorganic Matrix

“…The SOD1 mimics, [CuZn(dien) 2 (µ-Im)(ClO 4 ) 2 ]ClO 4 and [Cu 2 (dien) 2 (µ-Im)(ClO 4 ) 2 ]ClO 4 (Him is imidazolate, dien is diethylenetriamine), were also encapsulated in MSS, and the obtained materials showed an improved anti-inflammatory activity [144].…”