Visualization and quantification of polymer distribution in microcapsules by confocal laser scanning microscopy (CLSM)

Confocal laser scanning microscopy (CLSM) was employed in order to characterize microcapsules. Microcapsules were prepared by complex coacervation: gelatin and arabic gum were labelled with fluorescent markers. In the capsule wall a homogeneous distribution for both gelatin and arabic gum throughout the capsule wall was depicted. By the use of CLSM and a computational image analysis the quantification of the labelled polymer in the wall material was possible. Adding fluorescently labelled casein as a macromolecular model compound to the coacervation process, a gradiental distribution in the wall material was observed with highest concentration of casein at the oil-wall interface. The influence of casein concentration on its deposition behaviour in the capsule wall was imaged successfully and thereafter quantified by computational image analysis.