EDTA-Functionalized Carbon Dots–Metal Nanozymes Based on Coordination Chemistry: Species of Metal Ions Determines Enzyme-Mimicking Catalyzed Activities

Metal ion-carbon based nanomaterials served as nanozymes to mimic the biocatalytic performance of natural enzymes. However, there are still challenges in constructing carbon dots (CDs)–metal nanozymes with the same coordination structure based on coordination chemistry and revealing the effect of metal ion species on enzyme-mimicking catalyzed activities. Herein, EDTA-functionalized carbon dots–metal (CDs EDTA -Me) nanozymes with different metal ions (Fe 3+, Cu 2+, and Co 2+ ) and the same coordination structures are synthesized based on coordination chemistry. Species of metal ions of CDs EDTA -Me nanozymes determines enzyme-mimicking activities. CDs EDTA -Fe, CDs EDTA -Cu, and CDs EDTA -Co display significant peroxidase (POD)-mimicking, superoxide dismutase (SOD)-mimicking activities, and hydroxyl radical (•OH) scavenging ability, respectively. Compared with horseradish peroxidase, the affinity of CDs EDTA -Fe to H 2 O 2 is improved by 47 times. The V m value of CDs EDTA -Fe with TMB as the substrate is 1.19 × 10 –7 M s –1 . POD-mimicking activity of CDs EDTA -Me nanozymes increases linearly with the increase of stability constants of CDs EDTA -Me, which indicates that the POD-mimicking activity of CDs EDTA -Me can be predicted by stability constants of CDs EDTA -Me. CDs EDTA -Me provides a coordination chemistry strategy for the construction of CDs-metal nanozymes and rational improvement of enzyme-mimicking activities.