Evaluation of the antimicrobial activity of nanoparticles based on chitosan crosslinked with phytic acid and loaded with daptomycin against sensitive Staphylococcus aureus strains

This study focused on determining whether the antimicrobial activity of the lipopeptide antibiotic daptomycin improves when it is loaded into chitosan-based nanoparticles (NPs). The nanoparticulate systems were developed through the ionic gelation method employing phytic acid as a crosslinking agent. Physicochemical characterisation of the nanoparticles (NPs) was carried out by measurements of particle size, polydispersity index (PDI), and zeta potential. Antimicrobial evaluation was performed using a susceptible S. aureus strain using the broth microdilution method. The results showed a particle size of 453.9 ± 4.7 nm, a polydispersity index of 0.245 ± 0.04, and a zeta potential of +29.4 ± 0.3 mV. Notably, the antimicrobial evaluation revealed that daptomycin reduces the minimum inhibitory concentration (MIC) from 64 to 4 μg/mL upon loading into the nanoparticle, demonstrating an interesting potential as a pharmaceutical nanoformulation.