EFFECT OF VARIOUS POLOXAMER COATINGS ON INVITRO ADHESION OF ISOHEXYLCYANOACRYLATE NANOSPHERES TO RAT ILEAL SEGMENTS UNDER LIQUID FLOW

This work evaluates the bioadhesive properties of isohexylcyanoacrylate nanocapsules coated with poloxamers 407, 238, 403 and poloxamine 908 compared to nanoparticles coated with poloxamer 407. Nanocapsules (oil droplets surrounded by a polymeric wall) and nanoparticles (plain polymeric spheres) were prepared, labelled with covalently linked with tetraiodinated I-125-phthalocyanine-Zn and laid on the rat ileal segment in vitro. After 0 and 10 min following transfer of nanospheres, a liquid flow was started. In all cases studied, a fraction of the nanospheres was not adherent when perfusion was initiated and was recovered in the first fraction. The other fraction, representing approx. 45% of the nanospheres, adhered firmly and was removed very slowly by the liquid flow. In addition, when nanocapsules were coated with poloxamers 238 and 407, the percentage adhesion increased between 0 and 10 min. Our results demonstrate that the greatest extent of mucoadhesion was achieved with poloxamers possessing a short central polyoxypropylene (POP) chain and long polyoxyethylene (POE) side chains. The results are discussed on the basis of diffusion of the POE groups into the mucin network and creation of secondary chemical adhesive bonds (Van der Waals type) between the nanosphere coating and mucus.