Metal ions-driven multi-enzyme activity of PEI-carbon dots-based nanozyme to improve antibacterial ability

• Post-modification was applied to design carbon dots based-nanozymes with multi-enzyme-like activities. • The effects of eleven different metal ions on the activity of nanozyme were systematically studied. • Cu + /Cu 2+ ions could significantly enhance (29.7-fold) and generate new enzyme-like activity. • The Mn 2+ /Mn 3+ coordinated with Cu 2+ /Cu + is beneficial to boost antibacterial and antibiofilm. • The minimum inhibitory concentration of PEI@Mn/Cu + -CDs(solid) could reach 4 µg/mL. How to effectively eliminate bacterial biofilms still poses significant challenges, and the further improvement of enzymatic catalytic activity is crucial for the removal of bacterial biofilms. Herein, eleven metal ions were engineered onto polyethyleneimine chelated Mn-doped-carbon dots (PEI@Mn-CDs) through post-synthesis modification to further enhance the catalytic activity and endow the new enzyme-like activity. It is worth noting that the obtained PEI@Mn/Cu + -CDs and its solid by Cu + addition showed wider pH application range, more surprising multienzyme-like activity and better antibacterial activity. Compared with PEI@Mn-CDs, the V max of PEI@Mn/Cu + -CDs is increased by 29.7 times, and the minimum inhibitory concentration can reach 4 µg/mL. Mechanism investigation revealed that Cu + as the additional catalytic sites was integrated with PEI@Mn-CDs by the metal-amine/carboxyl coordination strategy, which is conducive to the improvement of electron transfer efficiency and the generation of free radicals. Furthermore, PEI@Mn/Cu + -CDs could enter the inside of bacteria and produce free radicals to kill bacteria, showing great potential against bacteria, drug-resistant bacteria and biofilms. This work provides an effective strategy for the design of highly efficient antibacterial and antibiofilm nanozymes .