Ru Nanoparticles Ligated by an N-Heterocyclic Carbene Derived from Uracil Nucleoside as Selective Antimicrobial...

Metal nanoparticles (MNPs) effectively combat pathogens due to their nonspecific toxicity, reducing the chance of bacterial resistance. Natural-based stabilizing ligands enhance the stability and targeting of MNPs while minimizing toxicity to human cells. In this context, ura-NHC-stabilized Ru NPs (Ru@ura-NHC) have been successfully synthesized following an organometallic approach, employing Ru(COD)(COT) as the metal precursor and, for the first time, a zwitterionic uracil-6-yl-imidazolium betaine (ura-zwt) as the NHC precursor. The mesomeric properties of ura-zwt enabled its use as an air-stable NHC precursor for the one-pot synthesis of Ru@ura-NHC with 100% atom economy and without byproduct formation. A combined theoretical/experimental study was conducted to investigate the coordination of the uracil-based NHC onto the Ru surface, indicating that the coordination of the neutral form (ura-NHC) is preferred over the zwitterionic form (ura-zwt). Evaluation of the antimicrobial properties of Ru@ura-NHC revealed that the coated Ru NPs exhibit selective activity against Staphylococcus aureus, which is beneficial as it minimizes off-target effects and reduces selective pressure for resistance.