Rational design of polymeric nanozymes with robust catalytic performance via copper-ligand coordination

Incorporating copper (Cu) ions into polymeric particles can be a straightforward strategy for mimicking copper enzymes, but it is challenging to simultaneously control the structure of the nanozyme and of the active sites. In this report, we present a novel bis-ligand (L2) containing bipyridine groups connected by a tetra-ethylene oxide (4EO) spacer. In phosphate buffer the Cu-L2 mixture forms coordination complexes that (at proper composition) can bind polyacrylic acid (PAA) to produce catalytically active polymeric nanoparticles with well-defined structure and size, which we refer to as 'nanozymes'. Manipulating the L2/Cu mixing ratio and using phos-phate as a co-binding motif, cooperative copper centres are realized that exhibit promoted oxidation activity. The structure and activity of the so-designed nanozymes remain stable upon increasing temperature and over mul-tiple cycles of application. Increasing ionic strength causes enhanced activity, a response also seen for natural tyrosinase. By means of our rational design we obtain nanozymes with optimized structure and active sites that in several respects outperform natural enzymes. This approach therefore demonstrates a novel strategy for devel-oping functional nanozymes, which may well stimulate the application of this class of catalysts.

Automated summary

In this study, a novel bis-ligand (L2) with bipyridine groups connected by a tetra-ethylene oxide (4EO) spacer was used to form coordination complexes with copper ions in phosphate buffer, which could then bind polyacrylic acid (PAA) to produce catalytically active polymeric nanoparticles with well-defined structure and size, referred to as 'nanozymes'. By controlling the L2/Cu mixing ratio and using phosphate as a co-binding motif, cooperative copper centers with promoted oxidation activity were realized. These designed nanozymes demonstrated stable structure and activity even at higher temperatures and multiple application cycles. Increasing ionic strength enhanced their activity, similar to natural tyrosinase. This rational design approach resulted in nanozymes with optimized structure and active sites that outperformed natural enzymes, suggesting the potential application of this class of catalysts.