Methotrexate-loaded chitosan nanogels as 'Trojan Horses' for drug delivery to brain: preparation and in vitro/in vivo characterization.

Methotrexate-loaded hydrogel nanoparticles were prepared and after in vitro characterization, their transport across blood-brain barrier was investigated in vivo in intact animals in this study. The ionic gelation method was used for preparation of drug-loaded nanogels, after optimized by a systematic multi-objective optimization approach. After surface-modification with polysorbate 80, nanoparticles with the final particle size, poly-dispersity index (PDI), loading efficiency (LE) and loading capacity (LC) of 118.54 ± 15.93 nm, 0.35 ± 0.05, 61.82 ± 6.84%, and 53.68 ± 3.09% were obtained, respectively. The in vitro drug release study indicated non-Fickian diffusion kinetic, apparently governed by both diffusion of the drug out of the nanoparticles and swelling/disintegration of the polymeric network as characterized by a Weibull model for both surface-treated and untreated nanogels. After intravenous administration of surface-modified and unmodified nanogels compared to the free drug, all with the same dose of 25 mg/kg, remarkably higher brain concentrations of methotrexate were achieved with the nanogel formulations in comparison to the free drug (in some cases, more than 10-fold); but there were no significant differences between the surface-modified and unmodified nanogels in all the time points tested.