Development of methotrexate loaded fucoidan/chitosan nanoparticles with anti-inflammatory potential and enhanced skin permeation

In this study, fucoidan/chitosan nanoparticles were developed for the topical delivery of methotrexate towards the treatment of skin-related inflammatory diseases. Based on the fucoidan/chitosan (F/C) weight ratio, three different nanoparticles (1F/1C; 3F/1C; 5F/1C) were produced and characterized. Methotrexate was loaded in these polymeric nanoparticles achieving a drug loading of ca. 14% and an entrapment efficiency of 96, 87 and 80% for 1F/1C; 3F/1C and 5F/1C nanoparticles, respectively. Methotrexate-loaded fucoidan/chitosan nanoparticles exhibited size within the 300–500 nm range, positive zeta potential for 1F/1C nanoparticles (+60 mV) and negative surface charge for the 3F/1C and 5F/1C nanoparticles (−40 and −45 mV, respectively). Methotrexate loaded in 3F/1C and 5F/1C nanoparticles did not affect cells viability and presented lower cytotoxicity than free methotrexate, in fibroblasts and human keratinocytes. MTX-loaded fucoidan/chitosan nanoparticles lead to a significant reduction of pro-inflammatory cytokines produced by activated human monocytes. Skin permeation studies showed that methotrexate-loaded nanoparticles permeated the pig ear skin barrier reaching after 6 h, a 2.7- and 3.3-fold increase for 3F/1C and 5F/1C nanoparticles, relative to free methotrexate. In conclusion, fucoidan/chitosan nanoparticles, in particular the ratio 5F/1C, is safe, exerts an anti-inflammatory effect and increase skin permeation thus can potentially be used for methotrexate topical delivery.