Iron/dextran sulfate multilayered microcapsules for controlled release of 10-hydroxycamptothecin

Stable 10-hydroxycamptothecin (HCPT) microcrystals with a length of about 5-10μm and a ζ-potential of -38.5mV were produced by pH-induced reprecipitation in presence of a stabilizer hydroxypropylmethylcellulose. Sequential layer growth was achieved by the layer-by-layer (LbL) assembly of Fe³⁺ and dextran sulfate (DS) on the surface of HCPT microcrystals via both electrostatic interaction and chemical complexation process. The satisfactory drug loading content (67.2±0.82%) as well as high encapsulation efficiency (60.56±0.82%) for four bilayers of Fe³⁺/DS coating was achieved. Both in vitro and in vivo release study revealed that the release time increased as the number of deposited Fe³⁺/DS bilayers increased. These results indicated that such iron-polysaccharide multilayered microcapsules can be a promising approach for the construction of an effective controlled release delivery system of HCPT as well as other drugs with potential cytotoxicity or short half-life time.