Surfactant-dependence of nanoparticle treatment in murine experimental colitis

Inflammatory bowel disease is a chronic relapsing inflammation of the gut with the two main forms being ulcerative colitis and Crohn's disease. Nanoparticulate drug carrier systems have been proven to enhance the therapeutic efficiency and to diminish adverse effects of the anti-inflammatory treatment due to their size dependent accumulation in the inflamed regions of the gut. The influence of surface properties on the accumulation selectivity and intensity of such nanoparticles is mainly unclear. Accordingly sized particles (~ 200 nm) were prepared by the emulsification solvent evaporation technique using different surfactants (polysorbate 20, sodium dodecyl sulphate, sodium cholate, cetyltrimethylammonium bromide, polyvinyl alcohol). In a murine colitis model the particles prepared with polysorbate 20 as surfactant led to a 34.8-fold higher particle content in the inflamed areas of the colon compared to the healthy gut and to a 4.5-fold increase of the particle content in the inflamed segments compared to particles prepared with sodium dodecyl sulphate. This effect translates also into a significantly higher mitigating effect when entrapping betamethasone into such nanoparticles. This study shows the importance of surface properties for the passive targeting approach in experimental colitis. The influence seems to be as important as the influence of the particle size.