[Taste-masking mechanism of layer-by-layer self-assembly coating investigated by synchrotron radiation-based Fourier-transform infrared spectromicroscopy].

Ibuprofen lipid pellets prepared by melting method could mask the bitter taste of the drug to some extent. The pellets were further coated with chitosan (cationic) and gelatin (anionic) by ionic interaction layer- by-layer self-assembly (LBL) coating to improve masking effects. In this paper, the release percentage of drugs in short time (1 min) was utilized as an indicator for the taste-masking, and it had confirmed the LBL coating inhibited the release of model drug of ibuprofen. Synchrotron radiation-based Fourier-transform infrared spectromicroscopy (SR-FTIR) has been applied to investigate the material distributions on the cross section of pellets and film. Characteristic absorptions of the compositions were obtained by SR-FTIR single spectrum scanning. The distributions of the drug and materials in coated films were determined by SR-FTIR mapping. The FTIR absorptions of chitosan and gelatin on the surface of lipid pellets was examined to verify the existence of chitosan and gelatin on the surface and a film formed using SR-FTIR ratio analysis. Whilst pellets coated only by chitosan or gelatin did not show the typical absorption of chitosan or gelatin, which confirmed the effects of ionic interaction on the film forming process. In conclusion, the method of SR-FTIR established for the study of the existence and distribution of materials in coated film offers a new choice for researches on membranes/films in drug delivery systems and pharmaceutical preparations.