Influence of the surface characteristics of PVM/MA nanoparticles on their bioadhesive properties.

The aim of this work was to investigate the influence of the cross-linkage of poly(methylvinylether-co-maleic anhydride) (PVM/MA) nanoparticles with increasing amounts of 1,3-diaminopropane (DP) and, eventually, bovine serum albumin (BSA) on their gastrointestinal transit and bioadhesive properties. The fluorescently-labelled formulations were orally administered to rats and, at different times, the amount of nanoparticles in both the lumen content and adhered to the gut mucosa were quantified. The gut transit was evaluated by calculating the gastric (k(ge)) and intestinal (k(ie)) emptying rates. The adhered fraction of nanoparticles in the whole gut was plotted versus time and, from these curves, the intensity, capacity and extent of the adhesive interactions were estimated. The bioadhesive potential of PVM/MA was much higher when formulated as nanoparticles (NP) than in the solubilised form in water. However, k(ge) and k(ie) increased by increasing the extent of cross-linkage of nanoparticles with DP, while the capacity to develop adhesive interactions and the intensity of the adhesive phenomenon were significantly higher for non-hardened than for DP-cross-linked carriers. In contrast, the BSA-coating of cross-linked nanoparticles significantly decreased k(ge) and k(gi), whereas the intensity of the bioadhesive phenomenon was significantly higher than for NP. In summary, the adhesivity of the nanoparticles appears to modulate their gastrointestinal transit profile.