Dendrocin ZM1 Nanoconjugates with Carbon Quantum Dots: A ROS-Generating Platform for Combating Multidrug-Resistant Bacteria.

INTRODUCTION

The global increase in multidrug-resistant (MDR) bacterial infections highlights the urgent need for novel antimicrobial strategies. Antimicrobial peptides (AMPs), such as Dendrocin ZM1 derived from Zataria multiflora Boiss. offer promising therapeutic potential, but face limitations including poor stability and dose-dependent cytotoxicity. We developed a nanoconjugate of Dendrocin ZM1 with carbon quantum dots (CQDs) to enhance antimicrobial efficacy and reduced cytotoxicity.

METHODS

The nanoconjugates were synthesized and characterized using FTIR, XPS, TEM, DLS, and fluorescence spectroscopy. Antibacterial activity against MDR Gram-positive and Gram-negative strains was evaluated using MIC determination, time-killing kinetics, ROS production, and ROS-scavenger rescue experiments. Hemolysis and MTT assays assessed biocompatibility on human red blood cells and HEK-293 cells.

RESULTS

Dendrocin ZM1-CQDs showed a 2 to 4-fold reduction in MIC values compared with Dendrocin ZM1 alone, and its rapid bactericidal kinetics reached a reduction of ≥3-log10 CFU/mL within 30-60 min at 2× MIC. ROS measurements showed a 3 to 4-fold increase in intracellular ROS levels, with scavenger treatments restoring bacterial viability, confirming ROS-mediated bacterial killing. Cytotoxicity assays showed >90% cell viability and <8% hemolysis even at high concentrations, indicating low toxicity to mammalian. Dendrocin ZM1-CQD nanoconjugates significantly enhance antibacterial efficacy while maintaining excellent biocompatibility.

DISCUSSION: The synergistic combination of AMPs and CQDs offers a promising nanobiotechnology platform for next-generation antimicrobial therapeutics targeting MDR pathogens.