Antimicrobial activity of echinacea-loaded metal-organic framework against Pseudomonas aeruginosa

This study evaluated the antibacterial and antibiofilm activity of Echinacea-loaded amino-functionalized UIO-66 MOF nanoparticles against clinical Pseudomonas aeruginosa isolates. Echinacea-loaded amino-functionalized UIO-66 metal-organic framework nanoparticles (UIO-66-NH₂-Ea) were synthesized and characterized using scanning electron microscopy (SEM), transmission electron microscopy (TEM), entrapment efficiency (EE%), in vitro release studies of Echinacea angustifolia, and physical stability assessments. Antibacterial assays, including minimum inhibitory concentration (MIC), minimum bactericidal concentration (MBC), time-kill assays, and biofilm inhibition assays, were performed. Gene expression of arr-2 and arr-4 was analyzed using quantitative real-time polymerase chain reaction (qRT-PCR) following treatment with UIO-66-NH₂-Ea. Echinacea-loaded UIO-66-NH₂ nanoparticles showed a size of 235.0 ± 7.4 nm, PDI of 0.140 ± 0.013, and entrapment efficiency of 72.53 ± 1.83%. A sustained release (~ 60% at 72 h) was observed compared to nearly complete release of free extract within 24 h. Stability showed significant changes in particle size, PDI, and entrapment efficiency over 60 days (p < 0.001). MIC (15.62-125 µg/mL) and MBC (31.25-250 µg/mL) values were up to four-fold lower than free Echinacea angustifolia (250-500 and 250-1000 µg/mL). Time-kill assays confirmed superior bactericidal activity. Biofilm formation was significantly inhibited (p < 0.001), and arr-2 and arr-4 expression was markedly downregulated compared to free extract (p < 0.001). These findings highlight the in vitro potential of Echinacea-loaded UIO-66-NH₂ nanoparticles as an effective antibacterial and antibiofilm platform against P. aeruginosa isolates. However, further in vivo studies are required to evaluate their safety and efficacy, and to better assess their translational potential.