Pinostrobin-Functionalized Gold Nanoparticles with Enhanced Antibacterial and Antibiofilm Effects Against Pseudomonas aeruginosa

Pseudomonas aeruginosa is a clinically significant pathogen with strong biofilm-forming capacity, leading to persistent infections and high resistance toward conventional antibiotics. Nanotechnology based therapeutics have emerged as a promising solution to overcome these limitations. In this study, pinostrobin-functionalized gold nanoparticles (Pin-AuNPs) were evaluated for their antibacterial and antibiofilm activities against P. aeruginosa. Although gold nanoparticles and flavonoid compounds have individually demonstrated antibacterial activity, their integration as a synergistic antibiofilm nano-system against P. aeruginosa remains underexplored. Pin-AuNPs were prepared using a previously validated synthetic protocol. Pinostrobin was immobilized onto the surface of citrate-stabilized AuNPs via non-covalent physisorption, with Tween 20 employed as a non-ionic surfactant to enhance colloidal stability and ensure efficient surface functionalization. Pin-AuNPs exhibited significantly enhanced antibacterial activity compared to free pinostrobin and bare AuNPs, demonstrating the advantage of nanoparticle-based functionalization. Here, we investigated antibacterial potency, biofilm inhibition, biofilm eradication and morphological alterations. Pin-AuNPs exhibited superior antibiofilm efficacy against P. aeruginosa, inhibiting biofilm formation by more than 80% and significantly reducing bacterial viability in established biofilms. Notably, Pin-AuNPs achieved a substantially lower MBIC₅₀ value (7.08 µg/mL, R² = 0.95) compared to bare AuNPs (25.79 µg/mL) and free pinostrobin (46.17 µg/mL), indicating markedly improved prevention of biofilm formation. In addition, Pin-AuNPs demonstrated the highest eradication potency against mature biofilms, with an MBEC₅₀ of 10.01 µg/mL, underscoring their potential as an effective nano-antimicrobial strategy for controlling biofilm-associated P. aeruginosa infections.