Abstract
An antioxidant nanocomposite was prepared by successive adsorption of redox active metal complexes (copper(ii)-bipyridyl and iron(iii)-citrate) and polyelectrolytes (poly(styrene sulfonate) and poly(diallyldimethyl ammonium)) on layered double hydroxide nanoclay. The experimental conditions were optimized in each preparation step and thus, the final composite formed highly stable colloids, i.e., excellent resistance against salt-induced aggregation was achieved. Due to the synergistic effect of the metal complexes, the developed composite showed remarkable activity in the dismutation of superoxide radicals, close to the one determined for the native superoxide dismutase enzyme. The obtained composite is highly selective for superoxide radical dismutation, while its activity in other antioxidant tests was close to negligible. Structural characterization of the composite revealed that the excellent superoxide radical scavenging ability originated from the advantageous coordination geometry around the copper(ii) center formed upon immobilization. The structure formed around the metal centers led to optimal redox features and consequently, to an improved superoxide dismutase-like activity. The catalytic antioxidant composite is a promising candidate to reduce oxidative stress in industrial manufacturing processes, where natural enzymes quickly lose their activity due to the harsh environmental conditions.
Highlights
Combating oxidative stress via decomposition of reactive oxygen species (ROS) attracts widespread contemporary interest due to its importance in both health-related and industrial processes.[1]
There was no significant change in electrophoretic mobility values indicating that the further added PSS remained dissolved in the solution
An antioxidant nanocomposite was developed by the sequential adsorption technique involving 2 polyelectrolytes and 2 enzyme mimicking metal complexes immobilized successively on a layered double hydroxide (LDH) nanoclay support
Summary
Combating oxidative stress via decomposition of reactive oxygen species (ROS) attracts widespread contemporary interest due to its importance in both health-related and industrial processes.[1]. Nanomaterials with antioxidant activity attract widespread interest in the scientific and technological communities.[8,9,10,11] These nanomaterials, the so-called nanozymes, usually contain redox active metals such as iron,[12] cerium[13] or manganese,[14] which are responsible for the reaction with ROS. Transition metal complexes with structures similar to the active centers of antioxidant enzymes can be synthesized and used as antioxidant agents.[15,16,17] Literature data shed light on the fact that appropriate structural mimicking usually gave rise to considerable functional mimicking too, i.e., once the active center was modelled adequately, the complexes possessed high ROS scavenging ability.[18,19,20,21,22]
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