Cellular uptake and toxicity of microparticles in a perspective of polymyxin B oral administration

Alginate/chitosan microparticles with a mean size less than 1 μm, designed in a previous work for the targeting of polymyxin B to M-cells and, then, to the lymphatic system, were assayed for transport ability by enterocytes. Caco-2 cell monolayer model, combined with confocal microscopy, showed that microparticles were endocytosed by the cells through an energy-dependent process, being the process saturable at 6 h incubation. Furthermore, microparticles maintained the biological activity of the antibiotic and decreased the antibiotic cytotoxicity against Vero cell cultures. Therefore, simultaneous pathways via both M-cells and enterocytes could be proposed for such a microparticulate carrier.