Surface Ligand Engineering Ruthenium Nanozyme Superior to Horseradish Peroxidase for Enhanced Immunoassay

Nanozymes have great potential to be used as an alternative to natural enzymes in a variety of fields. However, low catalytic activity compared with natural enzymes limits their practical use. It is still challenging to design nanozymes comparable to their natural counterparts in terms of the specific activity. In this study, a surface engineering strategy is employed to improve the specific activity of Ru nanozymes using charge-transferrable ligands such as polystyrene sulfonate (PSS). PSS-modified Ru nanozyme exhibits a peroxidase-like specific activity of up to 2820 U mg(-1), which is twice that of horseradish peroxidase (1305 U mg(-1)). Mechanism studies suggest that PSS readily accepts negative charge from Ru, thus reducing the affinity between Ru and Greek ano teleiaOH. Importantly, the modified Ru-peroxidase nanozyme is successfully used to develop an immunoassay for human alpha-fetoprotein and achieves a 140-fold increase in detection sensitivity compared with traditional horseradish-peroxidase-based enzyme-linked immunosorbent assay. Therefore, this work provides a feasible route to design nanozymes with high specific activity that meets the practical use as an alternative to natural enzymes.

Automated summary

Nanozymes have great potential as alternatives to natural enzymes, but their practical use is limited by their low catalytic activity compared to natural enzymes. This study employed a surface engineering strategy using charge-transferrable ligands, such as polystyrene sulfonate (PSS), to improve the specific activity of Ru nanozymes. The modified Ru nanozyme exhibited a peroxidase-like specific activity double that of horseradish peroxidase. The modified Ru-peroxidase nanozyme was successfully used to develop an immunoassay with significantly increased detection sensitivity compared to traditional enzyme-linked immunosorbent assay.