Correlation between the molecular morphology and the biocompatibility of bioadhesive carriers prepared from spray-dried starch/Carbopol® blends

Spray-dried Amioca® starch/Carbopol® 974P (C 974P; cross-linked poly(acrylic acid)) blends were evaluated as bioadhesive drug carriers and compared with equivalent physical mixtures. For both mixture types, the nano-morphology was determined by means of SEM and 13C-CP/MAS solid state NMR. Whereas phase separation occurs into individual starch and C 974P molecular domains for the physical mixtures, spray-drying results in homogeneous blends of Amioca® starch and C 974P.This intimate mixing improves the bioadhesive capacity significantly as compared to equivalent physical mixtures. Up to a 20 wt% content of C 974P, the spray-dried blends did not show any sign of irritation. This makes them promising biocompatible powders for application as safe bioadhesive carriers.