Nanozymes are defined as nanomaterials of enzyme-like functions, which are capable to overcome the limitations of natural enzymes in biomedical or industrial catalytic applications. These limitations include cost, difficult storage, and high sensitivity to the environmental conditions and that highly efficient enzymes are often obtained from genetically modified species, which are being controlled by increasingly strict regulations. Nanozymes became promising alternatives to native enzymes in the last decade, but several related questions such as engineering substrate specificity, understanding catalytic mechanism, tuning interparticle interactions and studying degradation must be still addressed. The present research aims for the design of nanozyme-based composites from preparation through characterization to in-lab validation of their efficiency.
Prussian blue and manganese oxide (MnO₂) nanoparticles of suspected antioxidant activities were synthesized by hydrothermal processes resulting in one-phase materials of narrow size distribution, as determined by scattering (DLS), spectroscopy (XPS, UV-Vis) and microscopy (SEM, TEM, AFM) techniques. These nanomaterials were found to mimic the function of superoxide dismutase (SOD), catalase (CAT) and peroxidase enzymes in biochemical tests, i.e., they have proven to act as antioxidant nanozymes.
To improve their limited colloidal stability, the nanozymes were aggregated with polystyrene latex particles using polyelectrolytes such as poly(diallyldimethylammonium chloride) (PDADMAC) for surface functionalization to adjust the charge balance during the heteroaggregation between the nanozymes and the latex. The obtained composites possessed excellent structural, colloidal, and functional stabilities confirming the advantages of the presence of the carrier latex particles. For instance, MnO₂ nanozyme-based composites showed both SOD and CAT activities even at high temperature (see image), where the natural enzymes quickly lose their activities.

Schematic illustration of the composition, structure and enzymatic (SOD and CAT) activity of the SPMn (latex-PDADMAC-MnO<sub>2</sub>) composite. The antioxidant tests were performed at elevated (75 <sup>o</sup>C) temperature.

Schematic illustration of the composition, structure and enzymatic (SOD and CAT) activity of the SPMn (latex-PDADMAC-MnO₂) composite. The antioxidant tests were performed at elevated (75 ^oC) temperature.

Nizar Alsharif

Appearances