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

Spray--dried Amioca(()R) starch/Carbopol(()R) 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(1)(3)C--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(()R) starch and C 974P. This intimate mixing improves the bioadhesive capacity significantly as compared to equivalent physical mixtures. Up to a 20wt% 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.