The Green Synthesis of Cu Nanoparticles and Investigation of the Antibacterial Properties and Cytotoxicity on Multidrug-Resistant E. coli.

Introduction: Although E. coli is considered a normal human microbiota, it may cause life-threatening infections such as septicemia, urinary tract infections, and enteric infections. Moreover, multidrug-resistant strains are a serious challenge in the clinic due to high mortality rates and the limited number of therapeutic options. Hence, the current study aimed to benefit from pink rose petals as a source of green synthesis of copper nanoparticles (Cu-NPs), to investigate the antibacterial features against multidrug-resistant E. coli, and to measure the cytotoxicity of Cu-NPs.

Methods: Pink rose petals were used as a reducing agent for Cu-NP synthesis, and then XRD, zeta potential, UV-Vis, FTIR, SEM, and DLS analyses were performed to characterize the synthesized NPs. Moreover, the MIC and zone of inhibition values of Cu-NPs were measured and compared to common antibiotics. Additionally, the MTT assay was performed to assess the cytotoxicity.

Results: The green synthesized Cu-NPs were spherical and uniform with a size of ~200 nm. The MIC of Cu-NPs was 1024 μg/ml on the MDR strain of E. coli, representing the antibacterial activity comparable to levofloxacin (p-value>0.05) but less than imipenem and trimethoprim (pvalue< 0.001). Moreover, the CC50 of synthesized Cu-NPs was 731.2 μg/ml and significantly lower than the studied antibiotics (p-value<0.001).

Conclusion: The findings may suggest Cu-NPs as a promising antibacterial strategy against MDR strains of E. coli, however, further studies are encouraged to clarify the safety of optimized doses.