Bioadhesive properties and biodistribution of cyclodextrin–poly(anhydride) nanoparticles

This work describes the preparation, characterization and evaluation of the nanoparticles formed by the copolymer of methyl vinyl ether and maleic anhydride (Gantrez® AN) and cyclodextrins, including β-cyclodextrin (CD) hydroxypropyl-β-cyclodextrin (HPCD) and 6-monodeoxy-6-monoamino-β-cyclodextrin (NHCD).The cyclodextrin–poly(anhydride) nanoparticles were prepared by a solvent displacement method and characterized by measuring the size, zeta potential, morphology and composition. For bioadhesion studies, nanoparticles were fluorescently labelled with rhodamine B isothiocianate (RBITC). For in vivo imaging biodistribution studies, 99mTc-labelled nanoparticles were used.Nanoparticles displayed a size of about 150 nm and a cyclodextrin content which was found optimal under the following experimental conditions: cyclodextrin/poly(anhydride) ratio of 0.25 by weight, 30 min of incubation time between the cyclodextrin and the polymer. Moreover, the oligosaccharide content was higher with CD than with NHCD and HPCD.Overall, cyclodextrin–poly(anhydride) nanoparticles displayed homogeneous bioadhesive interactions within the gut. The intensity of these interactions was higher than for control nanoparticles. The high bioadhesive capacity was observed for HPCD-NP and NHCD-NP which can be related with their rough morphology and, thus, a higher specific surface than for smooth nanoparticles (CD-NP). Finally, from in vivo studies, no evidence of translocation of distribution to other organs was observed when these nanoparticles were orally administered.