Hydrophobic Chitosan Nanoparticles Loaded with Carvacrol against Pseudomonas aeruginosa Biofilms

Abstract

<i>Pseudomonas aeruginosa</i> infections have become more challenging to treat and eradicate due to their ability to form biofilms. This study aimed to produce hydrophobic nanoparticles by grafting 11-carbon and three-carbon alkyl chains to a chitosan polymer as a platform to carry and deliver carvacrol for improving its antibacterial and antibiofilm properties. Carvacrol-chitosan nanoparticles showed ζ potential values of 10.5-14.4 mV, a size of 140.3-166.6 nm, and an encapsulation efficiency of 25.1-68.8%. Hydrophobic nanoparticles reduced 46-53% of the biomass and viable cells (7-25%) within <i>P. aeruginosa</i> biofilms. Diffusion of nanoparticles through the bacterial biofilm showed a higher penetration of nanoparticles created with 11-carbon chain chitosan than those formulated with unmodified chitosan. The interaction of nanoparticles with a 50:50 <i>w</i>/<i>w</i> phospholipid mixture at the air-water interface was studied, and values suggested that viscoelasticity and fluidity properties were modified. The modified nanoparticles significantly reduced viable <i>P. aeruginosa</i> in biofilms (0.078-2.0 log CFU·cm^-2) and swarming motility (40-60%). Furthermore, the formulated nanoparticles reduced the quorum sensing in <i>Chromobacterium violaceum</i>. This study revealed that modifying the chitosan polarity to synthesize more hydrophobic nanoparticles could be an effective treatment against <i>P. aeruginosa</i> biofilms to decrease its virulence and pathogenicity, mainly by increasing their ability to interact with the membrane phospholipids and penetrate preformed biofilms.