Controlled Release of 5-FU from Chi–DHA Nanoparticles Synthetized with Ionic Gelation Technique: Evaluation of Release Profile Kinetics and Cytotoxicity Effect

The ionic gelation technique allows us to obtain nanoparticles able to function as carriers for hydrophobic anticancer drugs, such as 5-fluoruracil (5-FU). In this study, reticulated chitosan– docosahexaenoic acid (Chi–DHAr) nanoparticles were synthesized by using a chemical reaction between amine groups of chitosan (Chi) and carboxylic acids of docosahexaenoic acid (DHA) and the presence of a link between Chi and DHA was confirmed by FT-IR, while the size and morphology of the obtained Chi-DHAr nanoparticles was evaluated with dynamic light scattering (DLS) and scanning electron microscopy (SEM), respectively. Drug-loading content (DLC) and drug-loading efficiency (DLE) of 5-FU in Chi-DHAr nanoparticles were 33.74 ± 0.19% and 7.9 ± 0.26%, respectively, while in the non-functionalized nanoparticles (Chir + 5FU), DLC, and DLE were in the ranges of 23.73 ± 0.14%, 5.62%, and 0.23%, respectively. The in vitro release profile, performed in phosphate buffer saline (PBS, pH 7.4) at 37 °C, indicated that the synthetized Chi–DHAr nanoparticles provided a sustained release of 5-FU. Based on the obtained regression coefficient value (R(2)), the first order kinetic model provided the best fit for both Chir and Chi-DHAr nanoparticles. Finally, cytotoxicity studies of chitosan, 5-FU, Chir, Chir + 5-FU, Chi-DHAr, and Chi-DHAr + 5-FU nanoparticles were conducted. Overall, Chi-DHAr nanoparticles proved to be much more biocompatible than Chir nanoparticles while retaining the ability to release the drug with high efficiency, especially towards specific types of cancerous cells.