Phytochemical-Potentiated Chitosan Nanoparticles Against Multidrug-Resistant Pseudomonas aeruginosa

Background and Objective: Multidrug-resistant (MDR) Pseudomonas aeruginosa remains a major cause of hospital-acquired infections, largely due to MexEF-OprN efflux-mediated resistance that reduces intracellular antibiotic accumulation. Curcumin and quercetin are natural efflux pump inhibitors (EPIs), but their clinical application is limited by poor solubility and bioavailability. The bojective ofg this study was to develop, optimize, and evaluate chitosan nanoparticles co-incorporating an antibiotic with curcumin or quercetin for efflux inhibition in MDR P. aeruginosa.

Materials and Methods: Nanoparticles were prepared by ionic gelation using chitosan and sodium tripolyphosphate (STPP). A 3² factorial design optimized chitosan (0.1–0.3%) and STPP (0.025–0.075%) concentrations with particle size and entrapment efficiency as critical quality attributes. Formulations were characterized for particle size, polydispersity index (PDI), zeta potential, entrapment efficiency, FTIR, DSC, FESEM, in vitro release, stability, and ethidium bromide (EtBr) accumulation.

Results: Optimized curcumin-loaded nanoparticles (0.2% chitosan, 0.05% STPP) exhibited a particle size of 205.7 nm, PDI of 0.39, zeta potential of +21.09 mV, and entrapment efficiencies of 82.2% and 75.8% for the antibiotic and curcumin, respectively. Quercetin-loaded nanoparticles showed a particle size of 283.0 nm, PDI of 0.74, zeta potential of +40.63 mV, and entrapment efficiencies of 83.4% and 79.1%, respectively. Although the formulations displayed relatively broad particle size distributions, a characteristic feature of ionic gelation-based chitosan systems, they maintained positive surface charge, colloidal stability, spherical morphology, sustained drug release for up to 16 h, enhanced EtBr accumulation, and physicochemical stability over three months.

Conclusion: Phytochemical-potentiated chitosan nanoparticles enhanced efflux inhibition and intracellular retention, demonstrating potential as a nanotherapeutic strategy for overcoming efflux-mediated resistance in MDR P. aeruginosa.