Fabrication of distilled water-soluble chitosan/alginate functional multilayer composite microspheres

Polysaccharides-based functional microspheres were fabricated under mild conditions. Firstly, magnetic alginate microspheres were prepared by emulsification/internal gelation and acted as substrates. Then the multilayer composite microspheres (MCM) were obtained through the layer-by-layer assembly of the distilled water-soluble chitosan and alginate. The components, morphology, and size distribution of the microspheres were characterized by element analysis (EA), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM) and laser particle size analyzer (LPSA). Both EA and XPS analysis results indicated that alternate immersion was an effective method for preparing MCM. Vibrating sample magnetometer, SEM and LPSA results showed that the microspheres had good dispersion, uniform particle size and were superparamagnetic. In addition, in vitro drug release behaviors of the microspheres were investigated by using hemoglobin (HB) and Coomassie brilliant blue G250 (CBB) as model drugs. It was found that the release rates of both HB and CBB from the composite microspheres were slower than those from the substrates.