Objective: The aim of this work was to prepare chitosan nanoparticles (CS NPs) using sodium tripolyphosphate (TPP) as crosslinker and to study the effect of chitosan polymeric properties and experimental conditions on the properties and stability of NPs.Methods: CS NPs were prepared by ionic gelation method, using TPP as a crosslinker. The particle size (PS), polydispersity index (PDI), zeta potential (ZP) and the morphologies of the NPs were studied. CS NPs prepared by varying the concentration of TPP, Chitosan molecular weight and its degree of deacetylation, the stirring speed, the rate of TPP addition and the freeze-drying method to study the effect of these variables on the NPs. The stability of the CS NPs was evaluated by storing aqueous suspensions of NPs and comparing the PS, PDI and ZP at the beginning and the end of the experiment.Results: This study shows that the PS, ZP and dispersity of the NPs depend on the chitosan polymeric properties and experimental conditions. The NPs sizes range between 145.73 and 724.23 nm. They all carried positive charges ranging between+4.32 and+43.67 mV. Most of the NPs have the same sizes after freeze-drying, but showed higher monodispersity and ZP, indicating higher stability. After twenty days of studying the stability, the NPs that had low ZP showed a large increment in size in comparison to the highly charged NPs.Conclusion: In conclusion, the polymeric properties and formulation variables in the ionic gelation method have a great influence on the CS NPs formed.

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(1) Background: Poly(lactic-co-glycolic acid) (PLGA) nanoparticles (NPs) loaded with Tobramycin were prepared using a solvent-evaporation method. (2) Methods: The NPs were coated with low molecular weight chitosan (LMWC) to enhance the mucoadhesiveness of PLGA-NPs. The following w/w ratios of tobramycin to LMWC were prepared: control (0:0.50), F0 (1:0.25), F0.5 (1:0.5), and F1 (1:1). (3) Results: The results showed that the size of the particles increased from 220.7 nm to 575.77 nm as the concentration of LMWC used in the formulation increased. The surface charge was also affected by the amount of LMWC, where uncoated-PLGA nanoparticles had negative charges (−2.8 mV), while coated-PLGA NPs had positive charges (+33.47 to +50.13 mV). SEM confirmed the size and the spherical homogeneous morphology of the NPs. Coating the NPs with LMWC enhanced the mucoadhesive properties of the NPs and sustained the tobramycin release over two days. Finally, all NPs had antimicrobial activity that increased as the amount of LMWC increased. (4) Conclusion: In conclusion, the formulation of mucoadhesive, controlled-release, tobramycin-LMWC-PLGA nanoparticles for the treatment of P. aeruginosa in cystic fibrosis patients is possible, and their properties could be controlled by controlling the concentration of LMWC.

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